{"id":55453,"date":"2026-06-25T08:46:11","date_gmt":"2026-06-25T08:46:11","guid":{"rendered":"https:\/\/zobai.com\/?p=55453"},"modified":"2026-06-25T08:46:25","modified_gmt":"2026-06-25T08:46:25","slug":"what-is-a-flanged-safety-valve","status":"publish","type":"post","link":"https:\/\/zobai.com\/ru\/blog\/what-is-a-flanged-safety-valve\/","title":{"rendered":"\u0427\u0442\u043e \u0442\u0430\u043a\u043e\u0435 \u0444\u043b\u0430\u043d\u0446\u0435\u0432\u044b\u0439 \u043f\u0440\u0435\u0434\u043e\u0445\u0440\u0430\u043d\u0438\u0442\u0435\u043b\u044c\u043d\u044b\u0439 \u043a\u043b\u0430\u043f\u0430\u043d?"},"content":{"rendered":"\n<style>\n.zobai-flanged-sv-blog{\n  --z-primary:#0f766e;\n  --z-primary-dark:#0b5f59;\n  --z-text:#20262d;\n  --z-muted:#5f6b75;\n  --z-line:#dfe6e8;\n  --z-soft:#f2f8f6;\n  --z-soft-2:#f8fbfa;\n  --z-warning:#9a5b00;\n  --z-warning-bg:#fff8e8;\n  --z-radius-md:16px;\n  --z-radius-lg:24px;\n  --z-shadow:0 14px 38px rgba(16,24,40,.08);\n  --z-container:1180px;\n  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margin:18px 0 0;\n  padding-left:18px;\n}\n.zobai-flanged-sv-blog .zobai-btn-row{display:flex;flex-wrap:wrap;gap:12px;margin-top:22px}\n.zobai-flanged-sv-blog .zobai-btn{\n  display:inline-flex;\n  min-height:44px;\n  align-items:center;\n  justify-content:center;\n  padding:11px 18px;\n  border-radius:999px;\n  font-weight:800;\n  text-decoration:none;\n}\n.zobai-flanged-sv-blog .zobai-btn:hover{text-decoration:none}\n.zobai-flanged-sv-blog .zobai-btn-primary{background:#fff;color:#0f766e}\n.zobai-flanged-sv-blog .zobai-btn-secondary{border:1px solid rgba(255,255,255,.75);color:#fff}\n.zobai-flanged-sv-blog .zobai-faq-item{\n  border:1px solid var(--z-line);\n  border-radius:var(--z-radius-md);\n  padding:18px;\n  margin:14px 0;\n  background:#fff;\n}\n.zobai-flanged-sv-blog .zobai-faq-item h3{margin:0 0 8px}\n.zobai-flanged-sv-blog .zobai-author,\n.zobai-flanged-sv-blog .zobai-standards{\n  margin:28px 0;\n  padding:20px;\n  border:1px solid var(--z-line);\n  border-radius:var(--z-radius-md);\n  background:var(--z-soft-2);\n}\n.zobai-flanged-sv-blog .zobai-author h2,\n.zobai-flanged-sv-blog .zobai-standards h2{font-size:1.35rem}\n@media (max-width:900px){\n  .zobai-flanged-sv-blog .zobai-hero-points,\n  .zobai-flanged-sv-blog .zobai-grid{grid-template-columns:1fr}\n  .zobai-flanged-sv-blog .zobai-rfq-list{grid-template-columns:1fr}\n}\n@media (max-width:640px){\n  .zobai-flanged-sv-blog .zobai-container{padding:0 16px}\n  .zobai-flanged-sv-blog .zobai-hero{padding:30px 20px;border-radius:18px}\n  .zobai-flanged-sv-blog .zobai-toc-list{display:block}\n  .zobai-flanged-sv-blog .zobai-toc-list li{margin:8px 0}\n  .zobai-flanged-sv-blog .zobai-toc-list a{width:100%}\n  .zobai-flanged-sv-blog .zobai-btn{width:100%}\n}\n<\/style>\n\n<article class=\"zobai-flanged-sv-blog\">\n  <div class=\"zobai-container\">\n    <section class=\"zobai-hero\" id=\"top\">\n      <p class=\"zobai-eyebrow\">Safety valve technical blog \u00b7 RFQ parameter validation<\/p>\n      <h2 class=\"zobai-hero-title\">Flanged Safety Valve RFQ Parameters Buyers Must Confirm<\/h2>\n      <p class=\"zobai-hero-lead\">A flanged safety valve is a safety valve or safety relief valve with bolted flange connections at the inlet, the outlet, or both. The flange connection helps the valve fit industrial piping and equipment nozzles, but it does not prove set pressure, relieving capacity, material suitability, or code compliance. This guide explains what a flanged safety valve is and, more importantly, which medium, pressure, temperature, capacity, flange, material, back pressure, and document data buyers should confirm before requesting an engineering quotation.<\/p>\n      <div class=\"zobai-hero-points\">\n        <div class=\"zobai-hero-point\">\n          <strong>Connection form<\/strong>\n          <span>Bolted flange joints define how the valve connects to equipment and piping.<\/span>\n        <\/div>\n        <div class=\"zobai-hero-point\">\n          <strong>Engineering boundary<\/strong>\n          <span>Flange size is not the same as documented relieving capacity.<\/span>\n        <\/div>\n        <div class=\"zobai-hero-point\">\n          <strong>RFQ focus<\/strong>\n          <span>Useful inquiries include process, pressure, capacity, flange, material, and document data.<\/span>\n        <\/div>\n      <\/div>\n    <\/section>\n\n    <figure class=\"zobai-figure\">\n      <img fetchpriority=\"high\" src=\"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-hero.webp\" alt=\"Flanged safety valve with visible inlet and outlet flange connections for industrial pressure protection\" title=\"Flanged safety valve with inlet and outlet flange connections\" width=\"1200\" height=\"900\" loading=\"eager\" fetchpriority=\"high\" decoding=\"async\">\n      <figcaption class=\"zobai-figcaption\">A flanged safety valve uses bolted flange connections, but flange size alone does not confirm relieving capacity.<\/figcaption>\n    <\/figure>\n\n    <nav class=\"zobai-toc\" aria-label=\"On this page\">\n      <p class=\"zobai-toc-title\">On this page<\/p>\n      <ul class=\"zobai-toc-list\">\n        <li><a href=\"#quick-answer\">Quick answer<\/a><\/li>\n        <li><a href=\"#definition\">Definition<\/a><\/li>\n        <li><a href=\"#applications\">Where it is used<\/a><\/li>\n        <li><a href=\"#selection-boundary\">Selection boundary<\/a><\/li>\n        <li><a href=\"#buyer-confirmation\">Buyer confirmation table<\/a><\/li>\n        <li><a href=\"#flange-details\">Flange details<\/a><\/li>\n        <li><a href=\"#capacity\">Capacity boundary<\/a><\/li>\n        <li><a href=\"#back-pressure\">Back pressure<\/a><\/li>\n        <li><a href=\"#comparison\">Threaded vs flanged<\/a><\/li>\n        <li><a href=\"#mistakes\">Mistakes to avoid<\/a><\/li>\n        <li><a href=\"#materials-documents\">Materials and documents<\/a><\/li>\n        <li><a href=\"#rfq\">Engineering review<\/a><\/li>\n        <li><a href=\"#faq\">FAQ<\/a><\/li>\n      <\/ul>\n    <\/nav>\n\n    <section class=\"zobai-section\" id=\"quick-answer\">\n      <h2>Quick Engineering Answer<\/h2>\n      <p>A flanged safety valve is selected when a pressure protection valve must connect to equipment or piping through bolted flanges rather than threaded connections. It is commonly considered for pressure vessels, boilers, process lines, skids, steam headers, gas systems, and discharge piping where plant flange standards, maintenance removal, or outlet piping requirements matter. However, a buyer should not specify one by flange size alone. The protected equipment, relief scenario, medium and phase, operating pressure, MAWP or design pressure, set pressure, required relieving capacity, relieving temperature, back pressure, inlet and outlet flange details, material, and applicable documents must be reviewed before selection. For broader product navigation, start from ZOBAI\u2019s <a href=\"https:\/\/zobai.com\/safety-valves\/\">industrial safety valves<\/a> hub, then review the <a href=\"https:\/\/zobai.com\/safety-valves\/flanged-safety-valves\/\">flanged safety valves<\/a> category page for flanged connection options.<\/p>\n      <div class=\"zobai-warning\">\n        <p><strong>Important:<\/strong> A flanged connection is a piping interface. It is not a substitute for relief sizing, capacity verification, material screening, back pressure review, or project code review.<\/p>\n      <\/div>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"definition\">\n      <h2>What Is a Flanged Safety Valve?<\/h2>\n      <p>A flanged safety valve is a pressure protection valve with flange-type pipe connections. The valve\u2019s safety function is still controlled by its internal design: spring force, disc, nozzle or seat geometry, lift behavior, back pressure sensitivity, material selection, and the documented capacity basis. The flange defines the mechanical interface between the valve and the piping or equipment nozzle.<\/p>\n      <p>Where a project uses the broader term <a href=\"https:\/\/zobai.com\/safety-valves\/pressure-relief-valves\/\">pressure relief valves<\/a>, buyers should still confirm whether the required device is a safety valve, safety relief valve, pressure relief valve, or another pressure relief configuration under the applicable project specification.<\/p>\n      <p>In many industrial projects, the inlet side of the valve is bolted to a vessel nozzle, boiler outlet, pressure line, or equipment branch connection. The outlet side may also be flanged, especially when discharge piping, a vent line, or a relief header is used. Some valves may have a flanged inlet and a different outlet arrangement, but in formal plant piping systems, both inlet and outlet connection details must be checked.<\/p>\n\n      <h3>What the flange connection does<\/h3>\n      <p>The flange connection helps the valve fit into a defined piping standard. It can support easier removal during maintenance compared with some threaded installations, especially where the valve is larger or where plant procedures require bolted joints. It also helps buyers and engineers specify inlet and outlet dimensions, pressure class or PN rating, facing type, and gasket compatibility.<\/p>\n      <p>For example, the RFQ may need to state whether the flange standard is ASME, EN, DIN, JIS, or another project requirement; whether the rating is Class 150, Class 300, PN16, PN40, or another rating; and whether the facing is RF, FF, RTJ, or another facing type. These details affect mechanical fit and sealing compatibility with the mating flange.<\/p>\n\n      <h3>What the flange connection does not prove<\/h3>\n      <p>A flange does not prove that the valve can relieve the required flow. A DN50 or 2-inch flanged connection does not automatically mean the valve has a specific documented or certified relieving capacity. The internal orifice, lift, valve type, medium, set pressure, relieving temperature, and manufacturer data determine the capacity basis.<\/p>\n      <p>A flange rating also does not equal the valve set pressure. Flange pressure-temperature ratings depend on material group, standard, temperature, and design conditions. A flange class or PN value must be checked against the project specification and service temperature. For capacity-related selection, buyers should review ZOBAI\u2019s <a href=\"https:\/\/zobai.com\/blog\/safety-valve-sizing-and-certified-relieving-capacity-guide\/\">safety valve sizing and certified relieving capacity<\/a> guide.<\/p>\n\n      <figure class=\"zobai-figure\">\n        <img loading=\"lazy\" src=\"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-engineering-diagram.webp\" alt=\"Simplified engineering diagram showing inlet flange outlet flange gasket and flow direction in a flanged safety valve\" title=\"Flanged safety valve engineering diagram with inlet and outlet flange callouts\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\">\n        <figcaption class=\"zobai-figcaption\">The flange connection defines the piping interface, while capacity depends on the internal relieving path and manufacturer data.<\/figcaption>\n      <\/figure>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"applications\">\n      <h2>Where Are Flanged Safety Valves Used?<\/h2>\n      <p>Flanged safety valves are used where pressure protection must be integrated with flanged industrial piping, equipment nozzles, or discharge systems. Typical applications may involve pressure vessels, boilers, steam headers, compressed gas systems, process skids, chemical lines, heat exchangers, and plant discharge systems. The connection style helps fit the valve into a defined piping interface, but the application alone does not complete selection.<\/p>\n      <p>For RFQ purposes, the important question is not only where the valve will be installed, but what the valve must protect and what relieving scenario governs the selection. A flanged safety valve used on a steam system may require different review inputs from one used for gas, vapor, liquid, thermal expansion, or corrosive service.<\/p>\n      <div class=\"zobai-grid\">\n        <div class=\"zobai-card\">\n          <h3>Connection context<\/h3>\n          <p>Flanged valves are commonly considered where bolted plant piping, equipment nozzles, or discharge headers are part of the system.<\/p>\n        <\/div>\n        <div class=\"zobai-card\">\n          <h3>RFQ value<\/h3>\n          <p>The flange standard, rating, facing, inlet size, and outlet size must be listed clearly before quotation.<\/p>\n        <\/div>\n        <div class=\"zobai-card\">\n          <h3>Engineering review<\/h3>\n          <p>Medium, set pressure, capacity, temperature, back pressure, and material remain separate from the flange connection.<\/p>\n        <\/div>\n      <\/div>\n      <p>For a broader valve selection path, see the <a href=\"https:\/\/zobai.com\/blog\/safety-valve-selection-guide\/\">safety valve selection guide<\/a>.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"selection-boundary\">\n      <h2>When a Flanged Safety Valve Is Suitable \u2014 and When the Specification Is Not Enough<\/h2>\n      <p>A flanged safety valve may be the right connection form, but the RFQ must still prove the service conditions. The table below separates useful selection signals from incomplete specifications.<\/p>\n      <div class=\"zobai-table-wrap\">\n        <table class=\"zobai-table\">\n          <thead>\n            <tr>\n              <th>Buyer statement<\/th>\n              <th>What it helps confirm<\/th>\n              <th>What is still missing<\/th>\n              <th>Engineering action<\/th>\n            <\/tr>\n          <\/thead>\n          <tbody>\n            <tr>\n              <td>\u201cWe need a flanged safety valve.\u201d<\/td>\n              <td>The connection type is likely flanged.<\/td>\n              <td>Medium, set pressure, capacity, temperature, flange standard, rating, material, and documents.<\/td>\n              <td>Request a full RFQ data set before selecting a model.<\/td>\n            <\/tr>\n            <tr>\n              <td>\u201cThe inlet is DN80 PN40.\u201d<\/td>\n              <td>Nominal inlet size and one flange rating reference.<\/td>\n              <td>Facing type, outlet flange, medium, set pressure, capacity, temperature, and material.<\/td>\n              <td>Check both inlet and outlet flange requirements separately.<\/td>\n            <\/tr>\n            <tr>\n              <td>\u201cThe old valve has the same flange size.\u201d<\/td>\n              <td>Replacement envelope may be similar.<\/td>\n              <td>Set pressure, capacity basis, material, standard, seat, back pressure, and service history.<\/td>\n              <td>Review nameplate, datasheet, photos, and installation layout.<\/td>\n            <\/tr>\n            <tr>\n              <td>\u201cThe outlet connects to a discharge header.\u201d<\/td>\n              <td>Outlet piping and back pressure may be relevant.<\/td>\n              <td>Superimposed pressure, built-up pressure, header layout, drainage, and reaction loads.<\/td>\n              <td>Screen for conventional, bellows balanced, or pilot operated review.<\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"buyer-confirmation\">\n      <h2>What Buyers Should Confirm for a Flanged Safety Valve<\/h2>\n      <p>A flanged safety valve RFQ should not begin and end with flange size. The supplier needs enough process, pressure, capacity, material, connection, and documentation data to check whether the requested valve is technically suitable.<\/p>\n\n      <div class=\"zobai-table-wrap\">\n        <table class=\"zobai-table\">\n          <thead>\n            <tr>\n              <th>Parameter to confirm<\/th>\n              <th>Why it matters<\/th>\n              <th>What to send ZOBAI<\/th>\n              <th>Common mistake<\/th>\n            <\/tr>\n          <\/thead>\n          <tbody>\n            <tr>\n              <td>Protected equipment<\/td>\n              <td>The selection depends on whether the valve protects a boiler, vessel, pipeline, skid, compressor, heat exchanger, or tank.<\/td>\n              <td>Equipment type, datasheet, drawing, or process description.<\/td>\n              <td>Requesting a valve without identifying what it protects.<\/td>\n            <\/tr>\n            <tr>\n              <td>Relief scenario<\/td>\n              <td>Blocked outlet, fire case, thermal expansion, regulator failure, and tube rupture can lead to different capacity requirements.<\/td>\n              <td>Governing relief case or project calculation basis.<\/td>\n              <td>Assuming one valve size fits all scenarios.<\/td>\n            <\/tr>\n            <tr>\n              <td>Medium and phase<\/td>\n              <td>Steam, gas, vapor, liquid, two-phase, corrosive, or dirty service affects sizing, materials, and valve configuration.<\/td>\n              <td>Medium name, phase, cleanliness, density, or process data if available.<\/td>\n              <td>Saying only \u201cair\u201d or \u201csteam\u201d without pressure and temperature.<\/td>\n            <\/tr>\n            <tr>\n              <td>Operating pressure<\/td>\n              <td>Operating pressure affects the margin below set pressure and possible leakage or simmer risk.<\/td>\n              <td>Normal operating pressure and maximum expected operating pressure.<\/td>\n              <td>Confusing operating pressure with set pressure.<\/td>\n            <\/tr>\n            <tr>\n              <td>MAWP \/ design pressure<\/td>\n              <td>The protected equipment limit is part of the pressure protection basis.<\/td>\n              <td>MAWP or design pressure of the protected equipment.<\/td>\n              <td>Using pipe flange rating as the equipment design pressure.<\/td>\n            <\/tr>\n            <tr>\n              <td>Set pressure<\/td>\n              <td>Set pressure defines when the valve is intended to open.<\/td>\n              <td>Required set pressure and unit.<\/td>\n              <td>Treating set pressure as the same as capacity.<\/td>\n            <\/tr>\n            <tr>\n              <td>Required relieving capacity<\/td>\n              <td>The valve must be able to relieve the required load under the governing condition.<\/td>\n              <td>Required mass or volumetric flow rate and calculation basis.<\/td>\n              <td>Assuming flange size determines capacity.<\/td>\n            <\/tr>\n            <tr>\n              <td>Relieving temperature<\/td>\n              <td>Temperature affects material, flange rating, gasket, seat, spring, and bolting selection.<\/td>\n              <td>Normal and relieving temperature.<\/td>\n              <td>Ignoring temperature when selecting flange rating or material.<\/td>\n            <\/tr>\n            <tr>\n              <td>Back pressure<\/td>\n              <td>Outlet pressure can affect stability, lift, and capacity, especially in discharge headers.<\/td>\n              <td>Superimposed and built-up back pressure, if known.<\/td>\n              <td>Ignoring outlet piping and discharge header effects.<\/td>\n            <\/tr>\n            <tr>\n              <td>Inlet flange details<\/td>\n              <td>The inlet must match the equipment nozzle or inlet piping.<\/td>\n              <td>Inlet size, flange standard, rating\/class\/PN, and facing type.<\/td>\n              <td>Sending only DN or inch size.<\/td>\n            <\/tr>\n            <tr>\n              <td>Outlet flange details<\/td>\n              <td>Outlet connection may differ from the inlet and must match discharge piping.<\/td>\n              <td>Outlet size, standard, rating\/class\/PN, and facing type.<\/td>\n              <td>Forgetting the outlet flange entirely.<\/td>\n            <\/tr>\n            <tr>\n              <td>Material requirements<\/td>\n              <td>Body, trim, spring, seat, gasket, and bolting must match medium and temperature.<\/td>\n              <td>Required body\/trim material, corrosion notes, and seat preference.<\/td>\n              <td>Selecting by body material only.<\/td>\n            <\/tr>\n            <tr>\n              <td>Certification and documents<\/td>\n              <td>Project acceptance may require specific tests, records, or standard references.<\/td>\n              <td>Required standard, inspection scope, and certificates.<\/td>\n              <td>Assuming all documents are automatically included.<\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n      <p>This table is not a substitute for formal relief sizing or code review. It is a practical way to prepare information for engineering discussion.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"flange-details\">\n      <h2>Inlet Flange, Outlet Flange, Rating and Facing Type<\/h2>\n      <p>For a flanged safety valve, the inlet and outlet flange details should be treated as separate specification items. The inlet flange connects the valve to the protected equipment or inlet piping. The outlet flange connects the valve to discharge piping, a vent line, a collection header, or another safe disposal route.<\/p>\n\n      <h3>Inlet flange details<\/h3>\n      <p>The inlet side is critical because excessive inlet pressure loss can affect valve performance. The inlet piping or equipment nozzle should be suitable for the selected valve, and the flange must match the mating connection. Buyers should confirm the inlet nominal size, flange standard, pressure rating or PN, facing type, and any project-specific requirement.<\/p>\n      <p>The inlet flange should not be specified only by nominal size. For example, \u201cDN50\u201d or \u201c2 inch\u201d does not tell the supplier the flange standard, pressure class, facing type, or design basis.<\/p>\n\n      <h3>Outlet flange and discharge piping<\/h3>\n      <p>The outlet side is often overlooked in RFQs. This can create problems when the valve must discharge into a pipe, vent stack, silencer, or header. Outlet flange size, standard, and rating must match the discharge connection. The outlet piping should also be reviewed for built-up back pressure, drainage, reaction force, support, and safe discharge direction.<\/p>\n\n      <h3>Facing type and gasket compatibility<\/h3>\n      <p>Flange facing type affects gasket selection and sealing compatibility. Common examples include raised face, flat face, and ring-type joint arrangements, depending on the standard and pressure class. The selected facing must match the mating flange and gasket requirement.<\/p>\n      <p>If the buyer is replacing an existing valve, photos of the old flange and nameplate are helpful, but they are not enough. The original datasheet and flange specification should also be checked. For related flange topics, buyers may review <a href=\"https:\/\/zobai.com\/standards\/asme-b16-5-flange-dimensions\/\">ASME B16.5 flange dimensions<\/a> and <a href=\"https:\/\/zobai.com\/standards\/pressure-temperature-ratings\/\">pressure-temperature ratings<\/a>.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"capacity\">\n      <h2>Flange Size Does Not Prove Relieving Capacity<\/h2>\n      <p>One of the most common selection errors is assuming that a safety valve with the same flange size has the same capacity. This is not correct.<\/p>\n      <p>The flange is the external connection. The relieving capacity depends on the internal flow path and documented valve performance. Two valves may have similar inlet flanges but different nozzle areas, disc lift, internal geometry, flow coefficients, and capacity basis. The medium also matters: steam, air, gas, vapor, and liquid services are not interchangeable without proper calculation.<\/p>\n\n      <figure class=\"zobai-figure\">\n        <img loading=\"lazy\" src=\"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-capacity-vs-flange-size.webp\" alt=\"Engineering comparison showing flange size does not determine safety valve relieving capacity\" title=\"Flange size versus relieving capacity comparison for safety valves\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\">\n        <figcaption class=\"zobai-figcaption\">Flange size is a connection detail; relieving capacity must be checked against the internal orifice, medium, set pressure and documented capacity basis.<\/figcaption>\n      <\/figure>\n\n      <h3>Connection size vs internal relieving path<\/h3>\n      <p>A larger flange may allow a larger valve body, but the actual relieving area is determined by the selected valve design. In many projects, the required capacity is determined first, then the valve size and connection are selected to suit that capacity and installation.<\/p>\n      <p>This is why a buyer should provide required relieving capacity in proper units, not only pipe size. If the calculation is not available, the buyer should at least provide the protected equipment, relief scenario, medium, pressure, and temperature so that the case can be reviewed.<\/p>\n\n      <h3>Required capacity vs documented or certified capacity<\/h3>\n      <p>Required capacity is the amount the valve must relieve under the governing case. Documented or certified capacity is the capacity basis provided by manufacturer data, certification data, or applicable project documentation. The two must be compared under the correct conditions.<\/p>\n\n      <div class=\"zobai-table-wrap\">\n        <table class=\"zobai-table\">\n          <thead>\n            <tr>\n              <th>Capacity term<\/th>\n              <th>Meaning<\/th>\n              <th>Why it matters<\/th>\n              <th>Buyer action<\/th>\n            <\/tr>\n          <\/thead>\n          <tbody>\n            <tr>\n              <td>Required relieving capacity<\/td>\n              <td>The flow the valve must relieve for the governing relief scenario.<\/td>\n              <td>It comes from process safety or equipment protection requirements, not from flange size alone.<\/td>\n              <td>Send the required flow rate, unit, medium, pressure, temperature, and calculation basis if available.<\/td>\n            <\/tr>\n            <tr>\n              <td>Selected orifice \/ internal relieving path<\/td>\n              <td>The internal flow path that determines how the valve can pass the relieving load.<\/td>\n              <td>Two valves with similar flanges may have different internal relieving areas.<\/td>\n              <td>Do not assume same flange size means same valve capacity.<\/td>\n            <\/tr>\n            <tr>\n              <td>Documented or certified capacity<\/td>\n              <td>The capacity basis provided by manufacturer data, project documentation, or certification where applicable.<\/td>\n              <td>It must be checked against the required relieving capacity under the correct service condition.<\/td>\n              <td>Ask for the capacity basis required by your project specification.<\/td>\n            <\/tr>\n            <tr>\n              <td>Connection size<\/td>\n              <td>The external inlet or outlet flange size used for piping connection.<\/td>\n              <td>It supports fit-up but does not independently prove relief performance.<\/td>\n              <td>Provide connection size together with process and capacity data.<\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n\n      <p>A valve quoted for steam service cannot be validated only by the same flange size used in a gas or liquid application. The medium, pressure, temperature, and applicable standard must be checked. Where API flanged PSV dimensions or standard references are relevant, see <a href=\"https:\/\/zobai.com\/standards\/api-526-flanged-safety-valves\/\">API 526 flanged safety valves<\/a>.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"back-pressure\">\n      <h2>Back Pressure and Outlet Piping Checks for Flanged Safety Valves<\/h2>\n      <p>Flanged safety valves are often installed with outlet piping. That makes the outlet side more than a mechanical connection detail. Discharge piping can introduce superimposed back pressure, built-up back pressure, drainage problems, reaction loads, and support issues. These factors may affect stability, lift, capacity, leakage, and the suitability of a conventional spring-loaded valve.<\/p>\n\n      <div class=\"zobai-table-wrap\">\n        <table class=\"zobai-table\">\n          <thead>\n            <tr>\n              <th>Outlet \/ back pressure condition<\/th>\n              <th>Possible effect<\/th>\n              <th>What to confirm<\/th>\n              <th>Selection implication<\/th>\n            <\/tr>\n          <\/thead>\n          <tbody>\n            <tr>\n              <td>Outlet discharges directly to atmosphere<\/td>\n              <td>Back pressure may be low, but reaction force and safe discharge still matter.<\/td>\n              <td>Outlet direction, support, drainage, noise, and safety of discharge location.<\/td>\n              <td>Conventional designs may be suitable if other conditions are acceptable.<\/td>\n            <\/tr>\n            <tr>\n              <td>Outlet connects to a short vent pipe<\/td>\n              <td>Built-up pressure and mechanical load may still occur.<\/td>\n              <td>Pipe length, bends, support, drainage, and allowable pressure drop.<\/td>\n              <td>Installation review is required before final selection.<\/td>\n            <\/tr>\n            <tr>\n              <td>Outlet connects to a common header<\/td>\n              <td>Variable superimposed back pressure may affect opening, lift, and capacity.<\/td>\n              <td>Header pressure range, simultaneous discharge cases, and built-up back pressure.<\/td>\n              <td>Balanced bellows or pilot operated review may be needed.<\/td>\n            <\/tr>\n            <tr>\n              <td>Outlet piping is heavy or poorly supported<\/td>\n              <td>Mechanical stress can be transferred to the valve body or flange joint.<\/td>\n              <td>Pipe support, alignment, expansion movement, and reaction force.<\/td>\n              <td>Correct installation and support are required before operation.<\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n\n      <p>Where back pressure may be significant, the buyer should not assume that a conventional valve is always suitable. The service may require review of a balanced bellows or pilot operated design, depending on the pressure conditions and applicable standards. For a dedicated discussion, see ZOBAI\u2019s <a href=\"https:\/\/zobai.com\/engineering\/back-pressure-and-bellows\/\">back pressure and bellows<\/a> guide.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"comparison\">\n      <h2>Threaded vs Flanged Safety Valve Quick Comparison<\/h2>\n      <p>Threaded and flanged safety valves can both protect pressure equipment when correctly selected. The connection choice depends on service conditions, piping design, maintenance practice, documentation requirements, and project standard. For a product-family reference, buyers can compare the requirements of <a href=\"https:\/\/zobai.com\/safety-valves\/threaded-safety-valves\/\">threaded safety valves<\/a> with the flanged connection checks described in this article.<\/p>\n      <p>The table below provides a quick buyer-level comparison only; final selection still depends on the actual working conditions and manufacturer data.<\/p>\n\n      <div class=\"zobai-table-wrap\">\n        <table class=\"zobai-table\">\n          <thead>\n            <tr>\n              <th>Selection factor<\/th>\n              <th>Threaded safety valve<\/th>\n              <th>Flanged safety valve<\/th>\n              <th>Buyer check<\/th>\n            <\/tr>\n          <\/thead>\n          <tbody>\n            <tr>\n              <td>Connection method<\/td>\n              <td>Screwed connection using a thread standard such as NPT, BSP, G, or Rc where applicable.<\/td>\n              <td>Bolted flange joint with gasketed mating surfaces.<\/td>\n              <td>Confirm the exact thread or flange standard before quotation.<\/td>\n            <\/tr>\n            <tr>\n              <td>Typical use context<\/td>\n              <td>Often used in smaller equipment, compact systems, or simpler piping arrangements.<\/td>\n              <td>Often used in plant piping, larger systems, equipment nozzles, and formal project specifications.<\/td>\n              <td>Confirm equipment type, line size, maintenance method, and project standard.<\/td>\n            <\/tr>\n            <tr>\n              <td>Installation and removal<\/td>\n              <td>Can be compact, but thread compatibility and sealing must be correct.<\/td>\n              <td>Easier to remove in many bolted piping systems, especially where maintenance access is planned.<\/td>\n              <td>Check available space, orientation, and isolation procedure.<\/td>\n            <\/tr>\n            <tr>\n              <td>Piping load and support<\/td>\n              <td>Threaded connections may be sensitive to installation stress if poorly supported.<\/td>\n              <td>Flanged systems still require proper support and alignment.<\/td>\n              <td>Do not let discharge piping load the valve body.<\/td>\n            <\/tr>\n            <tr>\n              <td>Documentation<\/td>\n              <td>May be suitable where project documentation requirements are simpler.<\/td>\n              <td>Often preferred where flange standard, rating, inspection, and document traceability are specified.<\/td>\n              <td>State required certificates and inspection documents in the RFQ.<\/td>\n            <\/tr>\n            <tr>\n              <td>Replacement risk<\/td>\n              <td>Thread standard mismatch is a common issue.<\/td>\n              <td>Same flange size may still hide rating, facing, material, or capacity differences.<\/td>\n              <td>Do not replace by appearance only.<\/td>\n            <\/tr>\n            <tr>\n              <td>Capacity confirmation<\/td>\n              <td>Still requires set pressure, medium, and capacity basis.<\/td>\n              <td>Still requires set pressure, medium, and capacity basis.<\/td>\n              <td>Connection type does not replace sizing review.<\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n      <p>This section is a quick connection-form comparison only. It should not be used as a shortcut for valve sizing, installation review, or project documentation review.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"mistakes\">\n      <h2>Selection Mistakes to Avoid Before RFQ<\/h2>\n      <p>A good RFQ reduces technical back-and-forth and helps the supplier identify unsuitable assumptions early. The most common mistakes are not complicated, but they can lead to wrong quotations or unsafe replacements.<\/p>\n\n      <h3>Selecting by flange size only<\/h3>\n      <p>A buyer may ask for \u201cDN80 flanged safety valve\u201d or \u201c3 inch Class 150 safety valve.\u201d This is not enough. The supplier still needs the medium, set pressure, required relieving capacity, temperature, valve type, material, flange standard, facing type, and documentation requirements.<\/p>\n\n      <h3>Treating flange rating as set pressure<\/h3>\n      <p>A flange rating or class is not the same as set pressure. It is part of the pressure-temperature rating system for the flange and depends on the standard, material, and temperature. The valve set pressure must be specified separately and reviewed against the protected equipment and applicable code.<\/p>\n\n      <h3>Ignoring outlet back pressure<\/h3>\n      <p>The outlet of a safety valve is not just an exhaust opening. If the outlet is connected to a long discharge pipe, header, silencer, or recovery system, back pressure may affect valve performance. The type and amount of back pressure should be reviewed before selecting a conventional, balanced, or pilot operated configuration.<\/p>\n\n      <h3>Replacing by appearance only<\/h3>\n      <p>A replacement valve should not be selected only because it has the same flange size or looks similar. The nameplate, original datasheet, set pressure, capacity basis, material, flange standard, facing type, installation layout, and service conditions should be checked. If the old valve has leakage, chatter, corrosion, vibration, or repeated maintenance issues, the replacement should include a review of the root cause, not only a like-for-like purchase.<\/p>\n      <p>For installation-related checks, see ZOBAI\u2019s <a href=\"https:\/\/zobai.com\/engineering\/safety-valve-installation-guide\/\">safety valve installation guide<\/a>.<\/p>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"materials-documents\">\n      <h2>Material, Seat, Spring and Document Screening<\/h2>\n      <p>A flange standard does not confirm whether the wetted parts, spring, seat, gasket, or documents are suitable. Material and document requirements should be screened before quotation because they affect cost, manufacturability, inspection scope, and project acceptance.<\/p>\n\n      <div class=\"zobai-table-wrap\">\n        <table class=\"zobai-table\">\n          <thead>\n            <tr>\n              <th>Screening item<\/th>\n              <th>Why it matters<\/th>\n              <th>Typical RFQ input<\/th>\n              <th>Confirmation boundary<\/th>\n            <\/tr>\n          <\/thead>\n          <tbody>\n            <tr>\n              <td>Body material<\/td>\n              <td>Must match pressure, temperature, medium, corrosion risk, and project material requirements.<\/td>\n              <td>Required material grade or project material specification.<\/td>\n              <td>Availability depends on selected model and project specification.<\/td>\n            <\/tr>\n            <tr>\n              <td>Trim \/ disc \/ nozzle<\/td>\n              <td>Affects sealing, wear, corrosion resistance, and compatibility with the process medium.<\/td>\n              <td>Medium, corrosion notes, cleanliness, and required trim material if specified.<\/td>\n              <td>Must be checked against manufacturer data.<\/td>\n            <\/tr>\n            <tr>\n              <td>Seat \/ seal<\/td>\n              <td>Temperature, leakage expectation, medium, and maintenance requirements affect seat selection.<\/td>\n              <td>Metal or soft seat preference, temperature, leakage requirement, if any.<\/td>\n              <td>Do not claim zero leakage or universal seat suitability.<\/td>\n            <\/tr>\n            <tr>\n              <td>Spring and bonnet area<\/td>\n              <td>Spring environment and bonnet style may matter for temperature, corrosion, steam, or special service.<\/td>\n              <td>Medium, ambient condition, bonnet requirement, and temperature.<\/td>\n              <td>Spring material and bonnet design must be confirmed by model.<\/td>\n            <\/tr>\n            <tr>\n              <td>Inspection and documents<\/td>\n              <td>Calibration, seat tightness, material records, and inspection documents may be required for acceptance.<\/td>\n              <td>Applicable standard, witness inspection, certificate requirement, and document list.<\/td>\n              <td>Documents must be confirmed before order; do not assume all documents apply.<\/td>\n            <\/tr>\n          <\/tbody>\n        <\/table>\n      <\/div>\n    <\/section>\n\n    <section class=\"zobai-section\" id=\"rfq\">\n      <h2>What to Send ZOBAI for Engineering Review<\/h2>\n      <p>To help ZOBAI review a flanged safety valve inquiry, provide the working conditions and connection details as completely as possible. If some data is missing, mark it as unknown rather than guessing.<\/p>\n\n      <h3>For new projects<\/h3>\n      <p>For new equipment or new piping systems, send the protected equipment type, relief scenario, medium, operating pressure, design pressure or MAWP, set pressure, required capacity, relieving temperature, inlet and outlet flange details, material requirements, and applicable standard. If the project specification mentions ASME, API, ISO, EN, GB, or another requirement, include the relevant requirement and document scope.<\/p>\n\n      <h3>For replacement<\/h3>\n      <p>For replacement, send photos of the existing valve, nameplate, inlet and outlet flanges, installation layout, and discharge piping. If available, also send the old datasheet, calibration record, seat leakage record, material document, and maintenance notes. A photo is useful for identification, but it should not be treated as a complete specification.<\/p>\n\n      <h3>For documentation review<\/h3>\n      <p>If the project requires inspection or certificates, state this before quotation. Possible documents may include set pressure calibration records, seat tightness test requirements, material records, dimensional checks, inspection release notes, or other project-specific documents. Availability and format must be confirmed against the selected model, applicable standard, and order scope.<\/p>\n\n      <figure class=\"zobai-figure\">\n        <img loading=\"lazy\" src=\"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-rfq-selection-checklist.webp\" alt=\"RFQ checklist visual for flanged safety valve medium set pressure capacity flange rating material and documentation\" title=\"Flanged safety valve RFQ and selection checklist\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\">\n        <figcaption class=\"zobai-figcaption\">A useful RFQ should include process data, pressure data, capacity basis, inlet and outlet flange details, materials and document requirements.<\/figcaption>\n      <\/figure>\n    <\/section>\n\n    <section class=\"zobai-section zobai-faq\" id=\"faq\">\n      <h2>FAQ About Flanged Safety Valves<\/h2>\n\n      <div class=\"zobai-faq-item\">\n        <h3>What is a flanged safety valve?<\/h3>\n        <p>A flanged safety valve is a safety valve or safety relief valve with bolted flange connections at the inlet, outlet, or both. For RFQ review, the flange confirms the connection style only; the buyer still needs to provide medium, set pressure, required capacity, temperature, back pressure, material, and document requirements.<\/p>\n      <\/div>\n\n      <div class=\"zobai-faq-item\">\n        <h3>Is a flanged safety valve the same as a flanged pressure relief valve?<\/h3>\n        <p>The terms may overlap in some industrial usage, but the correct terminology depends on the service, code, medium, and project specification. Buyers should confirm whether the application requires a safety valve, safety relief valve, pressure relief valve, or a specific standard-defined design before quotation.<\/p>\n      <\/div>\n\n      <div class=\"zobai-faq-item\">\n        <h3>Does flange size determine safety valve capacity?<\/h3>\n        <p>No. Flange size does not determine capacity by itself. Capacity depends on the internal orifice, valve design, lift, medium, set pressure, relieving temperature, and documented or certified capacity basis. The same flange size can still require different capacity review.<\/p>\n      <\/div>\n\n      <div class=\"zobai-faq-item\">\n        <h3>What flange details should I send before quotation?<\/h3>\n        <p>Send the inlet and outlet size, flange standard, rating or class or PN, facing type, and any project-specific piping requirement. If the inlet and outlet are different, list them separately so the piping interface and discharge connection can both be checked.<\/p>\n      <\/div>\n\n      <div class=\"zobai-faq-item\">\n        <h3>When should I choose flanged instead of threaded?<\/h3>\n        <p>A flanged safety valve is often preferred for larger piping, bolted plant systems, formal project flange standards, maintenance access, and discharge piping. A threaded valve may be suitable for smaller systems where the thread standard and service conditions are appropriate. Final selection depends on the actual service and project specification.<\/p>\n      <\/div>\n\n      <div class=\"zobai-faq-item\">\n        <h3>Can I replace an old valve with the same flange size?<\/h3>\n        <p>Not without further checking. The same flange size does not prove the same set pressure, capacity, material, facing type, flange rating, or code basis. Use the old nameplate, datasheet, installation photos, and service data to support replacement review.<\/p>\n      <\/div>\n\n      <div class=\"zobai-faq-item\">\n        <h3>What documents may be required for a flanged safety valve?<\/h3>\n        <p>Depending on the project, documents may include calibration records, seat tightness test requirements, material records, inspection documents, or standard-related documentation. These requirements should be stated before quotation and confirmed against the selected model and order scope.<\/p>\n      <\/div>\n    <\/section>\n\n    <section class=\"zobai-rfq\" id=\"cta\">\n      <h2>Request a Flanged Safety Valve Engineering Review<\/h2>\n      <p>A flanged safety valve should be selected from real operating data, not from flange size alone. Before quotation, prepare the protected equipment, relief scenario, medium, phase, operating pressure, MAWP or design pressure, set pressure, required relieving capacity, relieving temperature, back pressure, inlet and outlet flange standard, flange rating, facing type, material requirements, and document requirements.<\/p>\n      <p>Send this information to ZOBAI for engineering review before quotation. If you are replacing an existing valve, include the nameplate, old datasheet, valve photos, and installation layout. This helps ZOBAI check whether the requested flanged safety valve matches the service conditions, piping interface, capacity basis, and documentation requirements.<\/p>\n      <ul class=\"zobai-rfq-list\">\n        <li>Medium and phase<\/li>\n        <li>Protected equipment and relief scenario<\/li>\n        <li>Operating pressure, MAWP, and set pressure<\/li>\n        <li>Required relieving capacity and basis<\/li>\n        <li>Relieving temperature<\/li>\n        <li>Superimposed and built-up back pressure<\/li>\n        <li>Inlet and outlet flange standard, rating, and facing<\/li>\n        <li>Material, seat, spring, gasket, and document requirements<\/li>\n      <\/ul>\n      <div class=\"zobai-btn-row\">\n        <a class=\"zobai-btn zobai-btn-primary\" href=\"https:\/\/zobai.com\/ask-an-engineer\/\">Ask a Safety Valve Engineer<\/a>\n        <a class=\"zobai-btn zobai-btn-secondary\" href=\"https:\/\/zobai.com\/contacts\/\">Contact ZOBAI<\/a>\n      <\/div>\n    <\/section>\n\n    <section class=\"zobai-author\">\n      <h2>Technical Review Note<\/h2>\n      <p>This article is prepared for industrial buyers and engineers who need to define flanged safety valve RFQ data. It reflects general engineering communication principles for pressure protection inquiries. Final valve selection should be confirmed against the protected equipment, governing relief scenario, required capacity, applicable code, manufacturer data, selected model, and project specification.<\/p>\n    <\/section>\n\n    <section class=\"zobai-standards\">\n      <h2>Standards and Selection Limitation<\/h2>\n      <p>Standards such as ASME, API, ISO, EN, DIN, or GB may apply depending on the project location, protected equipment, and specification. This article provides RFQ preparation guidance only and does not replace formal relief sizing, code review, manufacturer-documented data, third-party inspection, or approval by the responsible engineer or authority. A standard name in an RFQ should be treated as a requirement to confirm, not as an automatic claim that every valve configuration is certified for that standard.<\/p>\n    <\/section>\n  <\/div>\n<\/article>\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@graph\": [\n    {\n      \"@type\": \"TechArticle\",\n      \"@id\": \"https:\/\/www.zobai.com\/en\/what-is-a-flanged-safety-valve\/#article\",\n      \"mainEntityOfPage\": {\n        \"@type\": \"WebPage\",\n        \"@id\": \"https:\/\/www.zobai.com\/en\/what-is-a-flanged-safety-valve\/\"\n      },\n      \"headline\": \"What Is a Flanged Safety Valve?\",\n      \"description\": \"A technical buyer guide explaining what a flanged safety valve is, why flange size does not prove relieving capacity, and which medium, pressure, flange, material and document data buyers should confirm before RFQ.\",\n      \"image\": [\n        \"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-hero.webp\",\n        \"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-engineering-diagram.webp\",\n        \"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-capacity-vs-flange-size.webp\",\n        \"https:\/\/zobai.com\/wp-content\/uploads\/2026\/06\/what-is-a-flanged-safety-valve-rfq-selection-checklist.webp\"\n      ],\n      \"about\": [\n        \"flanged safety valve\",\n        \"flanged pressure relief valve\",\n        \"safety valve RFQ parameters\",\n        \"flange standard\",\n        \"relieving capacity\",\n        \"safety valve selection\"\n      ],\n      \"author\": {\n        \"@type\": \"Organization\",\n        \"name\": \"ZOBAI\"\n      },\n      \"publisher\": {\n        \"@type\": \"Organization\",\n        \"name\": \"ZOBAI\",\n        \"url\": \"https:\/\/zobai.com\/\"\n      }\n    },\n    {\n      \"@type\": \"FAQPage\",\n      \"@id\": \"https:\/\/www.zobai.com\/en\/what-is-a-flanged-safety-valve\/#faq\",\n      \"mainEntity\": [\n        {\n          \"@type\": \"Question\",\n          \"name\": \"What is a flanged safety valve?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"A flanged safety valve is a safety valve or safety relief valve with bolted flange connections at the inlet, outlet, or both. For RFQ review, the flange confirms the connection style only; the buyer still needs to provide medium, set pressure, required capacity, temperature, back pressure, material, and document requirements.\"\n          }\n        },\n        {\n          \"@type\": \"Question\",\n          \"name\": \"Is a flanged safety valve the same as a flanged pressure relief valve?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"The terms may overlap in some industrial usage, but the correct terminology depends on the service, code, medium, and project specification. Buyers should confirm whether the application requires a safety valve, safety relief valve, pressure relief valve, or a specific standard-defined design before quotation.\"\n          }\n        },\n        {\n          \"@type\": \"Question\",\n          \"name\": \"Does flange size determine safety valve capacity?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"No. Flange size does not determine capacity by itself. Capacity depends on the internal orifice, valve design, lift, medium, set pressure, relieving temperature, and documented or certified capacity basis. The same flange size can still require different capacity review.\"\n          }\n        },\n        {\n          \"@type\": \"Question\",\n          \"name\": \"What flange details should I send before quotation?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"Send the inlet and outlet size, flange standard, rating or class or PN, facing type, and any project-specific piping requirement. If the inlet and outlet are different, list them separately so the piping interface and discharge connection can both be checked.\"\n          }\n        },\n        {\n          \"@type\": \"Question\",\n          \"name\": \"When should I choose flanged instead of threaded?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"A flanged safety valve is often preferred for larger piping, bolted plant systems, formal project flange standards, maintenance access, and discharge piping. A threaded valve may be suitable for smaller systems where the thread standard and service conditions are appropriate. Final selection depends on the actual service and project specification.\"\n          }\n        },\n        {\n          \"@type\": \"Question\",\n          \"name\": \"Can I replace an old valve with the same flange size?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"Not without further checking. The same flange size does not prove the same set pressure, capacity, material, facing type, flange rating, or code basis. Use the old nameplate, datasheet, installation photos, and service data to support replacement review.\"\n          }\n        },\n        {\n          \"@type\": \"Question\",\n          \"name\": \"What documents may be required for a flanged safety valve?\",\n          \"acceptedAnswer\": {\n            \"@type\": \"Answer\",\n            \"text\": \"Depending on the project, documents may include calibration records, seat tightness test requirements, material records, inspection documents, or standard-related documentation. These requirements should be stated before quotation and confirmed against the selected model and order scope.\"\n          }\n        }\n      ]\n    }\n  ]\n}\n<\/script>\n\n\n","protected":false},"excerpt":{"rendered":"<p>Safety valve technical blog \u00b7 RFQ parameter validation Flanged Safety Valve RFQ Parameters Buyers Must Confirm A flanged safety valve is a safety valve or safety relief valve with bolted flange connections at the inlet, the outlet, or both. The flange connection helps the valve fit industrial piping and equipment nozzles, but it does not&#8230;<\/p>","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-55453","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/posts\/55453","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/comments?post=55453"}],"version-history":[{"count":1,"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/posts\/55453\/revisions"}],"predecessor-version":[{"id":55458,"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/posts\/55453\/revisions\/55458"}],"wp:attachment":[{"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/media?parent=55453"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/categories?post=55453"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/zobai.com\/ru\/wp-json\/wp\/v2\/tags?post=55453"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}