{"id":53729,"date":"2026-05-21T09:41:12","date_gmt":"2026-05-21T09:41:12","guid":{"rendered":"https:\/\/zobai.com\/?page_id=53729"},"modified":"2026-06-05T01:16:27","modified_gmt":"2026-06-05T01:16:27","slug":"api-521-pressure-relief-systems","status":"publish","type":"page","link":"https:\/\/zobai.com\/fr\/standards\/api-521-pressure-relief-systems\/","title":{"rendered":"Syst\u00e8mes de d\u00e9charge de pression selon API 521"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-page\" data-elementor-id=\"53729\" class=\"elementor elementor-53729\" data-elementor-post-type=\"page\">\n\t\t\t\t<div class=\"elementor-element elementor-element-77a1787 e-con-full e-flex cmsmasters-bg-hide-none cmsmasters-bg-hide-none cmsmasters-block-default e-con e-parent\" data-id=\"77a1787\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-36251e5 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"36251e5\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-f4ff0c8 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-shortcode\" data-id=\"f4ff0c8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"shortcode.default\">\n\t\t\t\t\t\t\t<div class=\"elementor-shortcode\"><nav aria-label=\"breadcrumbs\" class=\"rank-math-breadcrumb\"><p><span class=\"last\">Home<\/span><\/p><\/nav><\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9af06c5 elementor-widget__width-initial cmsmasters-block-default cmsmasters-sticky-default elementor-invisible elementor-widget elementor-widget-heading\" data-id=\"9af06c5\" data-element_type=\"widget\" data-e-type=\"widget\" data-settings=\"{&quot;_animation&quot;:&quot;cmsmasters-fade-in-up&quot;}\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h1 class=\"elementor-heading-title elementor-size-default\">API 521 Pressure Relief Systems Guide for Relief Scenarios, Flare, Vent and Depressuring Design<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-08ae60c cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"08ae60c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\t<p>API 521 provides the system-level framework for identifying credible overpressure scenarios, estimating relieving and depressuring loads, and defining safe disposal routes. This guide shows how fire exposure, blocked outlet, tube rupture, control failure, flare header pressure and vapor depressuring requirements are translated into the process data needed for PSV sizing, valve selection and a complete RFQ.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9e9ca16 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"9e9ca16\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-69e37f6 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"69e37f6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm\" href=\"https:\/\/zobai.com\/contacts\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Request API 521 Relief Review<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-eed5631 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"eed5631\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm\" href=\"\/standards\/api-520-safety-valve-sizing\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">View API 520 Sizing Guide<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-38f5d45 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"38f5d45\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-b1e78b1 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"b1e78b1\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-ccbb333 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"ccbb333\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">API 521 Quick Links<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a57f64d elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"a57f64d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/api-521-pressure-relief-systems\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Relief Scenario Review<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/api-520-safety-valve-sizing\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">API 520 PSV Sizing<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"#fire-case-relief\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Fire Case Relief Review<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"#flare-back-pressure\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Flare &amp; Vent Header Review<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"#depressuring-systems\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Depressuring \/ Blowdown Systems<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/applications\/high-back-pressure\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">High Back Pressure Service<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-ca2bd19 e-con-full cmsmasters-effect cmsmasters-effect-type-transform e-flex cmsmasters-effect-hover-type-element cmsmasters-block-default e-con e-child\" data-id=\"ca2bd19\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;,&quot;position&quot;:&quot;absolute&quot;,&quot;cms_transform_hover_type&quot;:&quot;element&quot;}\">\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-83dc703 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"83dc703\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-0786fc5 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"0786fc5\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1e7506c elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"1e7506c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">API 521 is used at system level: it helps identify relief scenarios, required relieving rates, flare and vent loads, and depressuring requirements.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">API 520 usually answers the device sizing and selection question; API 521 helps define the credible overpressure case and relief system basis.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">For safety valve procurement, API 521 data should be converted into a clear RFQ: scenario, relieving capacity, phase, back pressure, disposal route and documents.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Final valve selection still requires protected equipment data, applicable code, certified capacity and manufacturer engineering confirmation.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-eef355c e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"eef355c\" data-element_type=\"container\" data-e-type=\"container\" id=\"api-521-overview\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-99d12ea e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"99d12ea\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-9a4c8bd cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"9a4c8bd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a API 521 Overview<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3832747 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"3832747\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">API 521 helps define the pressure relief system before the safety valve is sized<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-47f86dc cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"47f86dc\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tA safety valve datasheet is only as reliable as the relief scenario behind it. API 521 is commonly used to review how a process system can overpressure, what relieving rate is credible, whether several devices can relieve at the same time, and whether the downstream vent, flare, scrubber or closed relief header can accept the load.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-841be31 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"841be31\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tFor buyers, API 521 should not be treated as only a standard name on a purchase order. It should become practical engineering data: blocked outlet flow, fire case load, tube rupture basis, control valve failure, utility failure, thermal expansion, depressuring rate, back pressure and disposal route.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-4a3495d e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"4a3495d\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-c854b1f cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"c854b1f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">What this page helps you confirm<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a6191e5 elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"a6191e5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Which overpressure scenarios should be checked before sending a PSV RFQ.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">How API 521 connects to API 520, API 526, API 527, ASME and project specifications.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">What data is needed for fire case, blocked outlet, tube rupture and depressuring review.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">How flare header, vent stack, scrubber, closed drain and back pressure affect valve selection.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Which documents should be requested for EPC, refinery, petrochemical, LNG and gas plant projects.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-3973967 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"3973967\" data-element_type=\"container\" data-e-type=\"container\" id=\"relief-scenarios\">\n\t\t<div class=\"elementor-element elementor-element-38f7896 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"38f7896\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-d796ae2 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d796ae2\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Relief Scenarios<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4ff542a cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"4ff542a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Common API 521 relief scenarios that affect safety valve selection<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-53aa8bc cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"53aa8bc\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tThese are the system-level cases that often control the safety valve capacity, outlet system design and final RFQ requirements. The exact governing case depends on process data, protected equipment, control philosophy and project code basis.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-2773013 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"2773013\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-b4d74dc e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"b4d74dc\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-bf37b85 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"bf37b85\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">01<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d78f636 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d78f636\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Blocked Outlet \/ Closed Valve<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-66773ea cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"66773ea\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tA closed downstream valve, blocked exchanger outlet or isolated vessel can expose equipment to full upstream pressure or maximum inlet flow. This case often controls PSV capacity for separators, filters and process vessels.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5a3857e elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"5a3857e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/pressure-vessels\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Review Related Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-bf5d0b7 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"bf5d0b7\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-9e81b88 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"9e81b88\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">02<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-903a599 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"903a599\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">External Fire Exposure<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f7f89c0 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"f7f89c0\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tFire case relief can create large vapor generation in vessels with liquid inventory. It affects required relieving rate, flare load, discharge temperature and emergency relief philosophy.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-dac9b4f elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"dac9b4f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"#fire-case-relief\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Review Related Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-e3e753d e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"e3e753d\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a5a6933 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"a5a6933\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">03<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-24f729d cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"24f729d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Control Valve or Regulator Failure<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2b32676 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"2b32676\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tA failed-open control valve or pressure regulator may send high-pressure flow into lower-rated downstream equipment. The PSV should be sized from failed-open flow, not normal demand.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-3921846 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"3921846\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/skid-systems\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Review Related Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9cbd5f1 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"9cbd5f1\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t<div class=\"elementor-element elementor-element-76f5282 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"76f5282\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-e6bc060 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"e6bc060\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">04<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e3b3aa9 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"e3b3aa9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Heat Exchanger Tube Rupture<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-06e49bd cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"06e49bd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tTube rupture can transfer high-pressure fluid into a lower-pressure side. The review should compare pressure source, exchanger geometry, phase change, discharge route and dynamic response.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e7c5547 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"e7c5547\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/heat-exchangers\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Review Related Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d71c37f e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"d71c37f\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a7303b7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"a7303b7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">05<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-85709ad cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"85709ad\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Compressor Blocked Discharge<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-49f8a51 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"49f8a51\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tCompressor discharge relief should use credible compressor flow, discharge temperature, vibration, pulsation and recycle failure assumptions. Back pressure and outlet reaction force are important.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9d894c3 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"9d894c3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/compressors\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Review Related Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-2f9a795 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"2f9a795\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-b5634c3 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"b5634c3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">06<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f29ea0e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"f29ea0e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Thermal Expansion and Trapped Liquid<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ad4e28e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"ad4e28e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tBlocked-in liquid can overpressure quickly as temperature rises. Thermal relief valves may be needed on pipelines, pump discharge sections, loading lines and exchanger liquid sections.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-46c4731 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"46c4731\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/thermal-relief\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Review Related Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-b4ef3cb e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"b4ef3cb\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-317a074 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"317a074\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2a536c9 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"2a536c9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a API 521 vs API 520<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9060540 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"9060540\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">API 521 defines the system case; API 520 supports device sizing and selection<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cd059e7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"cd059e7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tAPI 521 and API 520 are often used together. API 521 helps determine why the system is relieving, how much it must relieve, where it discharges, and whether simultaneous relief or depressuring must be considered. API 520 is then commonly used to size and select the pressure-relieving device based on the resulting process data.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-ef8fbf6 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"ef8fbf6\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-333305a cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"333305a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Practical output for procurement<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0fdd231 elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"0fdd231\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Relief scenario name and calculation basis for each PSV tag.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Required relieving rate, phase, molecular weight, density, temperature and pressure.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Disposal route: atmosphere, vent stack, flare, scrubber, condenser, closed relief header or recovery system.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Superimposed and built-up back pressure for each relief device.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Required valve type: conventional, bellows, pilot operated, thermal relief, rupture disc combination or depressuring valve.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Required documents: datasheet, sizing report, scenario summary, flare load data and test certificates.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-66e3592 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"66e3592\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-999f929 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"999f929\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-380d081 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"380d081\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Application Cases<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d5e89e7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d5e89e7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">API 521 pressure relief system cases with typical RFQ data<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1498dcf cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"1498dcf\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tThese cases show how API 521 studies are converted into practical valve and relief system RFQ information. Final design must be confirmed by the project relief study, process datasheets and the applicable code authority.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-e5b1674 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"e5b1674\" data-element_type=\"container\" data-e-type=\"container\" id=\"fire-case-relief\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-66755e6 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"66755e6\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-5b5ab5c cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"5b5ab5c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Case 1: Hydrocarbon Separator External Fire Relief<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8a914cd cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"8a914cd\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">Fire Case \/ Flare Load<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d5efcab cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"d5efcab\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tProtected equipment: separator with liquid inventory. Typical API 521 data includes wetted area, fluid properties, latent heat or vapor generation basis, relieving pressure, required load, discharge temperature, flare header pressure and simultaneous fire area assumptions.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d02f211 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"d02f211\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-3767c08 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"3767c08\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Case 2: Gas Plant Compressor Discharge PSV<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9600e0a cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"9600e0a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">Blocked Discharge<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-176d5f7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"176d5f7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tProtected equipment: compressor discharge receiver and piping. Typical RFQ data includes compressor maximum flow, discharge pressure, temperature, gas composition, molecular weight, pulsation, vibration, relief header pressure and outlet reaction force.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-edf1670 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"edf1670\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-38ecc54 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"38ecc54\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-fbe8059 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"fbe8059\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Case 3: Heat Exchanger Tube Rupture Relief<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9cc2364 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"9cc2364\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">High-to-Low Pressure Failure<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-49812a3 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"49812a3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tProtected equipment: low-pressure shell or tube side. Typical data includes high-pressure source condition, exchanger side MAWP, tube count, rupture opening basis, two-phase risk, discharge route and whether dynamic pressure response is considered.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-39d7b2a e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"39d7b2a\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0f557bc cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"0f557bc\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Case 4: Downstream Protection After PRV Failure<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e197142 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"e197142\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">Regulator Failed Open<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5adf1d7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"5adf1d7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tProtected equipment: low-pressure downstream header. Typical data includes upstream pressure, regulator Cv or failed-open flow, downstream design pressure, set pressure, gas properties, vent stack or flare back pressure and noise review.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-307061b e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"307061b\" data-element_type=\"container\" data-e-type=\"container\" id=\"depressuring-systems\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-45a78a6 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"45a78a6\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-5a0dda8 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"5a0dda8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Case 5: LNG \/ LPG Transfer System Thermal Relief<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a7e0f1b cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"a7e0f1b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">Blocked-In Liquid<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-95f5989 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"95f5989\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tProtected equipment: isolated transfer line or loading arm. Typical data includes trapped volume, fluid, temperature rise, heat leak, set pressure, line rating, flashing behavior and discharge to tank return, flare or safe vent.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-b6cfc18 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"b6cfc18\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-69e6d52 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"69e6d52\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Case 6: Vapor Depressuring \/ Blowdown System<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-021b6b1 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"021b6b1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">Depressuring System<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c3d9a25 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"c3d9a25\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tProtected equipment: process segment requiring rapid inventory reduction. Typical data includes depressuring time target, initial and final pressure, inventory, temperature response, flare load, restriction orifice data, depressuring valve specification and noise \/ vibration review.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-5ac2fa8 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"5ac2fa8\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-99d8645 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"99d8645\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a671d95 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"a671d95\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Engineering Matrix<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ae037d4 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"ae037d4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">API 521 review matrix for PSV and relief system RFQs<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-14a13a1 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"14a13a1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tUse this matrix to convert a relief study into clear procurement language. It helps avoid incomplete RFQs that only provide valve size, flange rating or set pressure without the system basis.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-ed3d370 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"ed3d370\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-e768ea1 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"e768ea1\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0d47483 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"0d47483\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Relief Scenario<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-5f99385 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"5f99385\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tBlocked outlet, external fire, tube rupture, control failure, utility failure, thermal expansion, compressor blocked discharge or depressuring.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-2e78dfc e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"2e78dfc\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-80e3769 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"80e3769\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Required Relief Load<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d946370 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"d946370\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tMass flow or volumetric flow at relieving conditions, with basis stated clearly and units defined.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-1f98506 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"1f98506\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-bd3e511 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"bd3e511\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Relieving Conditions<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d8bffc7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"d8bffc7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tRelieving pressure, temperature, phase, vapor fraction, molecular weight, density, viscosity and compressibility where applicable.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d38b40b e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"d38b40b\" data-element_type=\"container\" data-e-type=\"container\" id=\"flare-back-pressure\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-a6d2caf e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"a6d2caf\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0a71dba cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"0a71dba\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Disposal System<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-46d5ba4 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"46d5ba4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tAtmospheric vent, flare header, scrubber, condenser, closed relief header, recovery system, drain or safe collection path.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-460531f e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"460531f\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-c080a17 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"c080a17\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Back Pressure<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9eea69b cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"9eea69b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tSuperimposed and built-up back pressure, flare header pressure, vent stack losses, silencer loss and common header effects.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-96597a8 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"96597a8\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-560977b cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"560977b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Valve Selection Impact<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-67244b5 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"67244b5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tConventional, balanced bellows, pilot operated, rupture disc combination, thermal relief valve or depressuring valve requirement.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-87b8173 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"87b8173\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-9678a93 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"9678a93\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a577812 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"a577812\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Related Standards<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-bdc5bd9 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"bdc5bd9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Standards normally used with API 521<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-21fef4e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"21fef4e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tAPI 521 is part of a broader relief system design package. The selected valve and documents may also reference device sizing, valve dimensions, seat tightness, pressure vessel code, process piping code and end-user specifications.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0aaef7d elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"0aaef7d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/api-520-safety-valve-sizing\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">API 520 Safety Valve Sizing<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/api-526-flanged-safety-valves\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">API 526 Flanged Safety Valves<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/api-527-seat-tightness-test\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">API 527 Seat Tightness Test<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/asme-safety-valve-standards\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">ASME Section VIII Safety Valves<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/asme-safety-valve-standards\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">ASME B31.3 Process Piping Relief<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<a href=\"\/standards\/iso-4126-safety-valve-standard\/\">\n\n\t\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-chevron-right\" viewBox=\"0 0 320 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M285.476 272.971L91.132 467.314c-9.373 9.373-24.569 9.373-33.941 0l-22.667-22.667c-9.357-9.357-9.375-24.522-.04-33.901L188.505 256 34.484 101.255c-9.335-9.379-9.317-24.544.04-33.901l22.667-22.667c9.373-9.373 24.569-9.373 33.941 0L285.475 239.03c9.373 9.372 9.373 24.568.001 33.941z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">ISO 4126 Safety Valve Standards<\/span>\n\t\t\t\t\t\t\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-bc83268 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"bc83268\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-b145498 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"b145498\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Document Package<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d459fbb cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d459fbb\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Typical API 521 relief system document package<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a2d20af elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"a2d20af\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Relief scenario summary for each protected equipment item.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Relieving load calculation or reference to approved relief study.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">PSV datasheet with set pressure, relieving capacity, phase and connection standard.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Flare, vent, scrubber or closed relief header back pressure information.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Depressuring \/ blowdown valve datasheet where applicable.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">General arrangement drawing, material certificates, calibration report, pressure test and seat tightness test.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Inspection, witness, nameplate and tag list requirements for EPC approval.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d0e0e10 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"d0e0e10\" data-element_type=\"container\" data-e-type=\"container\" id=\"rfq-checklist\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-d9f4075 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"d9f4075\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-674be2b cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"674be2b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a RFQ Checklist<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-878a01e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"878a01e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Information to send when your project references API 521<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6dd2899 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"6dd2899\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tA complete API 521-based RFQ should provide the relief scenario and downstream system information, not only valve size and set pressure. This allows the valve supplier to check capacity, back pressure, material, test documents and installation limits.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1a694c9 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"1a694c9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/contacts\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Send API 521 RFQ<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-030613d e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"030613d\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-238cc97 elementor-align-start elementor-icon-list--layout-traditional elementor-list-item-link-full_width cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-icon-list\" data-id=\"238cc97\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"icon-list.default\">\n\t\t\t\t\t\t\t<ul class=\"elementor-icon-list-items\">\n\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Protected equipment tag, description, MAWP \/ design pressure and design temperature.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Applicable relief scenario: fire, blocked outlet, tube rupture, regulator failure, utility failure, compressor blocked discharge or thermal expansion.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Required relieving rate with basis, units and calculation reference.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Medium composition, phase, molecular weight, density, viscosity, vapor fraction and special hazards.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Relieving pressure, relieving temperature, allowable overpressure and operating margin.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Back pressure: superimposed, built-up, flare header, vent stack, scrubber or closed system pressure.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Outlet system: atmosphere, flare, vent stack, scrubber, condenser, recovery, drain or closed relief header.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t\t\t<li class=\"elementor-icon-list-item\">\n\t\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-icon\">\n\t\t\t\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-check\" viewBox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M173.898 439.404l-166.4-166.4c-9.997-9.997-9.997-26.206 0-36.204l36.203-36.204c9.997-9.998 26.207-9.998 36.204 0L192 312.69 432.095 72.596c9.997-9.997 26.207-9.997 36.204 0l36.203 36.204c9.997 9.997 9.997 26.206 0 36.204l-294.4 294.401c-9.998 9.997-26.207 9.997-36.204-.001z\"><\/path><\/svg>\t\t\t\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t\t<span class=\"elementor-icon-list-text\">Required valve documents: datasheet, sizing report, MTC, calibration, pressure test and seat tightness test.<\/span>\n\t\t\t\t\t\t\t\t\t<\/li>\n\t\t\t\t\t\t<\/ul>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-3367e3e e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"3367e3e\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-a3d8683 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"a3d8683\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-828b962 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"828b962\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Common Errors<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d27679e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d27679e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Common API 521 relief system mistakes in safety valve procurement<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-d413eec cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"d413eec\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tMost procurement delays happen when the relief study output is not translated into a complete valve datasheet. These mistakes should be corrected before RFQ release.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-c9092d5 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"c9092d5\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-a5f8c37 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"a5f8c37\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-f762d63 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"f762d63\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Providing set pressure without relief scenario<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-79dc979 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"79dc979\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tThe supplier cannot confirm capacity if the RFQ does not state whether the case is fire, blocked outlet, regulator failure, compressor blocked discharge or thermal expansion.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-b45a657 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"b45a657\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2faf742 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"2faf742\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Ignoring flare header back pressure<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0868572 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"0868572\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tBack pressure can change valve type and capacity. It should be provided before choosing conventional, bellows or pilot operated safety valves.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9306988 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"9306988\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-d978dd1 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d978dd1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Using normal flow instead of relieving flow<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6a21882 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"6a21882\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tNormal process flow is often lower than failed-open, blocked outlet, compressor or fire-case relief load. The governing upset case controls sizing.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-8ed9982 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"8ed9982\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-0b57cfe e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"0b57cfe\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-23a50d3 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"23a50d3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Missing two-phase or flashing behavior<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-26f26e6 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"26f26e6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tTube rupture, reactor relief, fire case and cryogenic liquid relief may involve two-phase or flashing flow. This affects sizing and discharge design.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f6d5043 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"f6d5043\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2e9b8b3 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"2e9b8b3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Treating depressuring valves as ordinary PSVs<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-275c71d cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"275c71d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tBlowdown and depressuring valves need process timing, flow control, outlet noise, low-temperature and flare load review.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-34b35a8 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"34b35a8\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-c0488fa cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"c0488fa\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Not checking simultaneous relief loads<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-376b83a cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"376b83a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tMultiple valves may discharge into the same flare or vent header. Header capacity and combined back pressure must be evaluated.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-fcb1b31 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"fcb1b31\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-4c2282f e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"4c2282f\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1d71582 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"1d71582\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a Related Standards &amp; Engineering Pages<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-fb16722 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"fb16722\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">Continue your API 521 pressure relief systems review<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7a0de2b cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"7a0de2b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tUse these pages to connect system-level relief analysis with actual valve sizing, valve type selection, testing, equipment application pages and RFQ preparation.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-0d166ad e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"0d166ad\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-5234797 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"5234797\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0980dd8 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"0980dd8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">API 520 Safety Valve Sizing<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7fc3ad7 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"7fc3ad7\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-e9406b1 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"e9406b1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/standards\/api-520-safety-valve-sizing\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-72cdda6 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"72cdda6\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-cfe8698 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"cfe8698\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">API 526 Flanged Safety Valves<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ce8e06d cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"ce8e06d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-1d4c573 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"1d4c573\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/standards\/api-526-flanged-safety-valves\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-4d73b9f e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"4d73b9f\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-a66c02e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"a66c02e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">API 527 Seat Tightness Test<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-ec2270e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"ec2270e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-236767b elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"236767b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/standards\/api-527-seat-tightness-test\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-066d8cd e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"066d8cd\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-8b79cd5 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"8b79cd5\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1b1e775 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"1b1e775\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">High Back Pressure Service<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-af56a23 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"af56a23\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-81c281e elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"81c281e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/high-back-pressure\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d8dbf5f e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"d8dbf5f\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-9edb0f8 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"9edb0f8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Large Capacity Safety Valves<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-03ccaa8 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"03ccaa8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-445b5c4 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"445b5c4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/large-capacity\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-5ebd3ec e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"5ebd3ec\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2665bbe cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"2665bbe\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Frequent Cycling Service<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-aff435c cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"aff435c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-21ab8b5 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"21ab8b5\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/frequent-cycling\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-c975d0d e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"c975d0d\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-ced0f53 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"ced0f53\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-5da05ab cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"5da05ab\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Pressure Vessel Safety Valves<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-96b00f4 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"96b00f4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8a70c6e elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"8a70c6e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/pressure-vessels\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-9ee73b7 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"9ee73b7\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-8be5951 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"8be5951\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Compressor Safety Valves<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-142cc5d cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"142cc5d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-43ffb29 elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"43ffb29\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/compressors\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-72c6ae8 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"72c6ae8\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-eaa3e6d cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"eaa3e6d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Heat Exchanger Safety Valves<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cc12fbe cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"cc12fbe\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tOpen this related resource to complete the relief study, valve selection, sizing and documentation workflow.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7d0787f elementor-align-left cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-button\" data-id=\"7d0787f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t\t\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-md\" href=\"\/applications\/heat-exchangers\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Open Page<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-d5e845c e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"d5e845c\" data-element_type=\"container\" data-e-type=\"container\" id=\"faq\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-f199f50 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"f199f50\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-05c0183 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"05c0183\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<div class=\"elementor-heading-title elementor-size-default\">\u203a\u203a\u203a FAQ<\/div>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-2903e5e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"2903e5e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h2 class=\"elementor-heading-title elementor-size-default\">API 521 Pressure Relief Systems FAQ<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f9d06bf cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"f9d06bf\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tShort answers for common engineering and procurement questions related to API 521, pressure relief systems and safety valve RFQs.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-65b8a33 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"65b8a33\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-8ff3144 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"8ff3144\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-8877a94 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"8877a94\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">What is API 521 used for in pressure relief systems?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-8201851 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"8201851\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tAPI 521 is used to review pressure-relieving and depressuring systems, including relief scenarios, required relieving rates, fire case, flare and vent systems, back pressure, disposal routes and vapor depressuring requirements.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-b748b08 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"b748b08\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-8d23e76 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"8d23e76\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1493a76 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"1493a76\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">What is the difference between API 520 and API 521?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-42d0828 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"42d0828\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tAPI 521 focuses on the system-level pressure relief basis, including overpressure causes and discharge systems. API 520 is commonly used for sizing and selection of pressure-relieving devices after the relief case and required capacity are defined.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-ea97478 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"ea97478\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-f60c0fa e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"f60c0fa\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-db6e506 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"db6e506\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Which relief scenarios are commonly reviewed under API 521?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-122e489 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"122e489\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tCommon scenarios include blocked outlet, external fire, control valve failure, pressure regulator failure, heat exchanger tube rupture, compressor blocked discharge, utility failure, thermal expansion, chemical reaction and vapor depressuring.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-182784b e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"182784b\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-d9d6869 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"d9d6869\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-560ed51 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"560ed51\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Does API 521 determine the final safety valve model?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-f5640ec cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"f5640ec\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tNo. API 521 helps define the relief system basis and required load. Final valve model selection also requires API 520 sizing, applicable ASME or project code, connection standard, material selection, back pressure, test requirements and manufacturer confirmation.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-c61387a e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"c61387a\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-04a41a9 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"04a41a9\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-cbb4450 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"cbb4450\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">What data should be included in an API 521-based safety valve RFQ?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-cad1820 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"cad1820\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tAn API 521-based RFQ should include protected equipment, relief scenario, required relieving rate, relieving pressure, relieving temperature, medium composition, phase, back pressure, discharge route, applicable standards, material requirement, sizing report requirement and test documents.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-7031751 e-con-full e-flex cmsmasters-block-default e-con e-parent\" data-id=\"7031751\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t<div class=\"elementor-element elementor-element-c417300 e-con-full e-flex cmsmasters-block-default e-con e-child\" data-id=\"c417300\" data-element_type=\"container\" data-e-type=\"container\" data-settings=\"{&quot;background_background&quot;:&quot;classic&quot;}\">\n\t\t\t\t<div class=\"elementor-element elementor-element-d2b4c6f cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-heading\" data-id=\"d2b4c6f\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"heading.default\">\n\t\t\t\t\t<h3 class=\"elementor-heading-title elementor-size-default\">Why is back pressure important in API 521 relief system review?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a02cd29 cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-text-editor\" data-id=\"a02cd29\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t\t\t\t\t\tBack pressure from flare headers, vent stacks, scrubbers or closed relief systems can affect safety valve capacity, opening behavior and reseating. It may determine whether a conventional, balanced bellows or pilot operated valve is suitable.\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-33086fd e-flex e-con-boxed cmsmasters-block-default e-con e-parent\" data-id=\"33086fd\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-392438e cmsmasters-block-default cmsmasters-sticky-default elementor-widget elementor-widget-html\" data-id=\"392438e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<script type=\"application\/ld+json\">\r\n{\r\n  \"@context\": \"https:\/\/schema.org\",\r\n  \"@type\": \"FAQPage\",\r\n  \"@id\": \"https:\/\/zobai.com\/standards\/api-521-pressure-relief-systems\/#faq\",\r\n  \"url\": \"https:\/\/zobai.com\/standards\/api-521-pressure-relief-systems\/\",\r\n  \"name\": \"API 521 Pressure Relief Systems FAQ\",\r\n  \"mainEntity\": [\r\n    {\r\n      \"@type\": \"Question\",\r\n      \"name\": \"What is API 521 used for in pressure relief systems?\",\r\n      \"acceptedAnswer\": {\r\n        \"@type\": \"Answer\",\r\n        \"text\": \"API 521 provides guidance for pressure-relieving and vapor depressuring systems. 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This guide shows how fire exposure, blocked outlet, tube rupture, control failure, flare header pressure and vapor depressuring requirements are&#8230;<\/p>","protected":false},"author":2,"featured_media":0,"parent":52756,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-53729","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/pages\/53729","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/comments?post=53729"}],"version-history":[{"count":16,"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/pages\/53729\/revisions"}],"predecessor-version":[{"id":54681,"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/pages\/53729\/revisions\/54681"}],"up":[{"embeddable":true,"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/pages\/52756"}],"wp:attachment":[{"href":"https:\/\/zobai.com\/fr\/wp-json\/wp\/v2\/media?parent=53729"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}