{"id":14218,"date":"2026-08-07T20:32:08","date_gmt":"2026-08-07T12:32:08","guid":{"rendered":"https:\/\/raymonvalve.com\/?p=14218"},"modified":"2026-08-15T23:31:16","modified_gmt":"2026-08-15T15:31:16","slug":"pressure-seal-bonnet-vs-bolted-bonnet-valve-joint-design-pressure-temperature-service-maintenance-and-selection","status":"publish","type":"post","link":"https:\/\/raymonvalve.com\/fr\/pressure-seal-bonnet-vs-bolted-bonnet-valve-joint-design-pressure-temperature-service-maintenance-and-selection\/","title":{"rendered":"Pressure Seal Bonnet vs Bolted Bonnet: Engineering Selection Boundaries"},"content":{"rendered":"\t\t<div data-elementor-type=\"wp-post\" data-elementor-id=\"14218\" class=\"elementor elementor-14218\" data-elementor-post-type=\"post\">\n\t\t\t\t<article class=\"elementor-element elementor-element-d0db9308 e-con-full raymonvalve-blog-page rv-knowledge e-flex e-con e-parent\" data-id=\"d0db9308\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-e2155283 elementor-widget elementor-widget-html\" data-id=\"e2155283\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<style>\n.raymonvalve-blog-page{--rv-navy:#15334a;--rv-blue:#1677a8;--rv-amber:#e9a23b;--rv-ink:#24333d;--rv-muted:#60717d;--rv-line:#cbd8df;--rv-bg:#f5f8fa;--rv-white:#fff;max-width:1160px;margin:0 auto;padding:28px 22px 64px;color:var(--rv-ink);font-family:Arial,\"Helvetica Neue\",sans-serif;font-size:18px;line-height:1.72;overflow-wrap:anywhere}\n.raymonvalve-blog-page *{box-sizing:border-box}\n.raymonvalve-blog-page a{color:#116f9f;text-decoration-thickness:1px;text-underline-offset:3px}\n.raymonvalve-blog-page a:hover,.raymonvalve-blog-page a:focus{color:#0d567b}\n.raymonvalve-blog-page .rv-byline{margin:0 0 18px;color:var(--rv-muted);font-size:.94rem}\n.raymonvalve-blog-page .rv-jump-links{display:flex;flex-wrap:wrap;gap:9px 12px;align-items:center;margin:24px 0;padding:16px 18px;border:1px solid var(--rv-line);border-radius:12px;background:var(--rv-bg);font-size:.9rem}\n.raymonvalve-blog-page .rv-jump-links span{font-weight:700;color:var(--rv-navy)}\n.raymonvalve-blog-page .rv-jump-links a{display:inline-block;padding:5px 10px;border-radius:999px;background:var(--rv-white);border:1px solid var(--rv-line);text-decoration:none}\n.raymonvalve-blog-page h2{margin:52px 0 18px;color:var(--rv-navy);font-size:clamp(1.55rem,2.5vw,2.15rem);line-height:1.25;scroll-margin-top:90px}\n.raymonvalve-blog-page h3{margin:30px 0 10px;color:var(--rv-navy);font-size:clamp(1.16rem,2vw,1.42rem);line-height:1.35;scroll-margin-top:90px}\n.raymonvalve-blog-page p{margin:0 0 18px}\n.raymonvalve-blog-page ul,.raymonvalve-blog-page ol{margin:0 0 24px;padding-left:1.45em}\n.raymonvalve-blog-page li{margin:.42em 0}\n.raymonvalve-blog-page strong{color:#1c3444}\n.raymonvalve-blog-page .rv-boundary{margin:24px 0 30px;padding:20px 22px;border:1px solid #e8c98e;border-left:5px solid var(--rv-amber);border-radius:10px;background:#fff7e8;color:#4c3b1d}\n.raymonvalve-blog-page .rv-boundary p:last-child{margin-bottom:0}\n.raymonvalve-blog-page .rv-source-note{margin:22px 0 26px;padding:16px 18px;border:1px solid var(--rv-line);border-left:5px solid var(--rv-blue);border-radius:10px;background:var(--rv-bg);color:var(--rv-ink);font-size:.9rem;line-height:1.58}\n.raymonvalve-blog-page .rv-source-note strong{color:var(--rv-navy)}\n.raymonvalve-blog-page .rv-figure{margin:30px auto 38px;max-width:960px}\n.raymonvalve-blog-page .rv-figure--hero{max-width:1120px}\n.raymonvalve-blog-page .rv-figure img{display:block;width:100%;height:auto;border:1px solid var(--rv-line);border-radius:14px;background:var(--rv-bg)}\n.raymonvalve-blog-page .rv-figure figcaption{margin-top:10px;color:var(--rv-muted);font-size:.86rem;line-height:1.5}\n.raymonvalve-blog-page .raymonvalve-table-wrap{width:100%;margin:22px 0 34px;overflow-x:auto;border:1px solid var(--rv-line);border-radius:12px;background:var(--rv-white);-webkit-overflow-scrolling:touch}\n.raymonvalve-blog-page table{width:100%;min-width:880px;border-collapse:collapse;font-size:.88rem;line-height:1.45}\n.raymonvalve-blog-page th,.raymonvalve-blog-page td{padding:13px 14px;border-right:1px solid #e2e9ed;border-bottom:1px solid #e2e9ed;text-align:left;vertical-align:top}\n.raymonvalve-blog-page th{position:sticky;top:0;background:var(--rv-navy);color:var(--rv-white);font-weight:700}\n.raymonvalve-blog-page tr:nth-child(even) td{background:#f8fafb}\n.raymonvalve-blog-page tr:last-child td{border-bottom:0}\n.raymonvalve-blog-page th:last-child,.raymonvalve-blog-page td:last-child{border-right:0}\n.raymonvalve-blog-page .rv-owner-links{margin:48px 0 26px;padding:22px;border:1px solid var(--rv-line);border-radius:14px;background:var(--rv-bg)}\n.raymonvalve-blog-page .rv-owner-links>strong{display:block;margin-bottom:10px;color:var(--rv-navy);font-size:1.08rem}\n.raymonvalve-blog-page .rv-owner-links ul{display:grid;grid-template-columns:repeat(2,minmax(0,1fr));gap:8px 24px;margin:0;padding-left:1.25em}\n.raymonvalve-blog-page .rv-cta{margin:26px 0 0;padding:30px clamp(22px,4vw,42px);border-radius:16px;background:var(--rv-navy);color:var(--rv-white)}\n.raymonvalve-blog-page .rv-cta h2{margin-top:0;color:var(--rv-white)}\n.raymonvalve-blog-page .rv-cta p,.raymonvalve-blog-page .rv-cta strong{color:var(--rv-white)}\n.raymonvalve-blog-page .rv-cta a{display:inline-block;padding:10px 16px;border-radius:8px;background:var(--rv-white);color:var(--rv-navy);font-weight:700}\n@media (max-width:767px){.raymonvalve-blog-page{padding:20px 16px 48px;font-size:17px;line-height:1.65}.raymonvalve-blog-page h2{margin-top:42px}.raymonvalve-blog-page h3{margin-top:26px}.raymonvalve-blog-page .rv-jump-links{align-items:flex-start}.raymonvalve-blog-page .rv-jump-links span{width:100%}.raymonvalve-blog-page .rv-boundary{padding:17px 16px}.raymonvalve-blog-page .rv-figure{margin:24px 0 30px}.raymonvalve-blog-page .rv-figure figcaption{font-size:.82rem}.raymonvalve-blog-page table{min-width:760px;font-size:.84rem}.raymonvalve-blog-page th,.raymonvalve-blog-page td{padding:11px 12px}.raymonvalve-blog-page .rv-owner-links ul{grid-template-columns:1fr}.raymonvalve-blog-page .rv-cta{padding:24px 20px}}\n@media (max-width:420px){.raymonvalve-blog-page{font-size:16px}.raymonvalve-blog-page .rv-jump-links a{width:100%}.raymonvalve-blog-page table{min-width:720px}.raymonvalve-blog-page .rv-figure figcaption{font-size:.78rem}}\n.raymonvalve-blog-page{box-sizing:border-box}\n\n.raymonvalve-blog-page>p,.raymonvalve-blog-page>ul,.raymonvalve-blog-page>ol,.raymonvalve-blog-page>h2,.raymonvalve-blog-page>h3,.raymonvalve-blog-page>.rv-boundary,.raymonvalve-blog-page>.rv-source-note,.raymonvalve-blog-page>.rv-jump-links,.raymonvalve-blog-page>.rv-faq-list{max-width:820px;margin-left:auto;margin-right:auto}\n.raymonvalve-blog-page>.rv-owner-links,.raymonvalve-blog-page>.rv-cta{max-width:920px;margin-left:auto;margin-right:auto}\n.raymonvalve-blog-page .rv-faq-list{display:grid;gap:12px;margin-bottom:38px}\n.raymonvalve-blog-page .rv-faq-item{border:1px solid var(--rv-line);border-radius:12px;background:var(--rv-white);overflow:hidden}\n.raymonvalve-blog-page .rv-faq-item summary{position:relative;padding:18px 52px 18px 20px;color:var(--rv-navy);font-weight:700;line-height:1.4;cursor:pointer;list-style:none}\n.raymonvalve-blog-page .rv-faq-item summary::-webkit-details-marker{display:none}\n.raymonvalve-blog-page .rv-faq-item summary:after{content:\"+\";position:absolute;right:20px;top:50%;transform:translateY(-50%);color:var(--rv-blue);font-size:1.45rem;line-height:1}\n.raymonvalve-blog-page .rv-faq-item[open] summary:after{content:\"\u2212\"}\n.raymonvalve-blog-page .rv-faq-item summary:focus-visible{outline:3px solid #79b9d7;outline-offset:-3px}\n.raymonvalve-blog-page .rv-faq-answer{padding:0 20px 18px}\n.raymonvalve-blog-page .rv-faq-answer p:last-child{margin-bottom:0}\n.raymonvalve-blog-page .rv-cta li{color:var(--rv-white)}\n@media (max-width:420px){.raymonvalve-blog-page .rv-cta a{display:block;width:100%;text-align:center;white-space:normal}.raymonvalve-blog-page .rv-faq-item summary{padding:16px 46px 16px 16px}.raymonvalve-blog-page .rv-faq-answer{padding:0 16px 16px}}\n.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>p,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>ul,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>ol,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>h2,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>h3,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>.rv-boundary,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>.rv-source-note,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>.rv-jump-links,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>.rv-faq-list{max-width:820px;margin-left:auto;margin-right:auto}.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>.rv-owner-links,.raymonvalve-blog-page .rv-reading>.elementor-element>.elementor-widget-container>.rv-cta{max-width:920px;margin-left:auto;margin-right:auto}.raymonvalve-blog-page .rv-reading>.elementor-element+.elementor-element h2{border-top:1px solid var(--rv-line);padding-top:52px}<\/style>\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-e2d23f60 e-con-full rv-reading e-flex e-con e-parent\" data-id=\"e2d23f60\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-b6ce1c60 elementor-widget elementor-widget-html\" data-id=\"b6ce1c60\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<p class=\"rv-byline\"><strong>By Raymon Valve<\/strong> \u00b7 Engineering Decision Support<\/p>\n\n<p>A bolted bonnet seals the body\u2013bonnet joint through controlled bolting load applied to a gasket, while a pressure seal bonnet uses internal pressure to energize a seal ring inside the valve body. Pressure seal construction is often considered for demanding pressure-temperature duties. Bolted construction remains widely used where the specified valve design, joint calculation and maintenance route support it. Neither is universally better: the decision depends on operating and startup conditions, thermal cycles, valve family, materials, maintenance access, testing and the approved design basis.<\/p>\n\n<p>This comparison concerns an external pressure-boundary joint. It does not establish through-seat leakage, stem-packing leakage, control performance or suitability for a particular medium. Buyers reviewing <a href=\"https:\/\/raymonvalve.com\/gate-valves\/\">industrial gate valves<\/a> or <a href=\"https:\/\/raymonvalve.com\/globe-valves\/\">globe valve designs<\/a> must keep those decisions separate.<\/p>\n\n<nav class=\"rv-jump-links\" aria-label=\"Article sections\">\n  <span>Jump to:<\/span>\n  <a href=\"#pressure-seal-bonnet-vs-bolted-bonnet-quick-comparison\">Quick comparison<\/a>\n  <a href=\"#pressure-and-temperature-do-not-create-a-universal-crossover-point\">Selection boundary<\/a>\n  <a href=\"#failure-modes-and-what-to-verify\">Failure review<\/a>\n  <a href=\"#rfq-checklist-for-a-defensible-comparison\">RFQ checklist<\/a>\n  <a href=\"#frequently-asked-questions\">FAQ<\/a>\n<\/nav>\n\n<blockquote class=\"rv-boundary\" data-master-region=\"evidence-boundary\" aria-label=\"Engineering scope boundary\">\n<p><strong>Engineering scope:<\/strong> This article is a preliminary selection and RFQ framework. It does not establish a Raymon Valve product pressure-temperature range, bonnet construction, leakage performance, material suitability, compliance or certification. Those claims require controlled evidence for the exact offered valve.<\/p>\n<\/blockquote>\n\n<p class=\"rv-source-note\" data-media-id=\"14276\" data-evidence-role=\"non-evidentiary-engineering-illustration\" data-evidence-level=\"F0_UNVERIFIED\"><strong>Featured illustration:<\/strong> Bolted and pressure seal body\u2013bonnet joints use different loading principles. Actual geometry and suitability depend on the offered valve design. Engineering illustration only; not product evidence.<\/p>\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-52fc6c60 elementor-widget elementor-widget-html\" data-id=\"52fc6c60\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"pressure-seal-bonnet-vs-bolted-bonnet-quick-comparison\">Pressure Seal Bonnet vs Bolted Bonnet: Quick Comparison<\/h2>\n\n<p>The useful first question is not \u201cWhich bonnet is stronger?\u201d It is \u201cHow must the offered body\u2013bonnet joint remain sealed throughout the specified pressure-temperature cycle, and what evidence will prove it?\u201d<\/p>\n\n<div class=\"raymonvalve-table-wrap\" role=\"region\" aria-label=\"Scrollable technical table 1\" tabindex=\"0\"><table>\n<thead>\n<tr>\n<th>Review point<\/th>\n<th>Bolted bonnet<\/th>\n<th>Pressure seal bonnet<\/th>\n<th>Buyer verification<\/th>\n<\/tr>\n<\/thead>\n<tbody><tr>\n<td>Primary joint-sealing basis<\/td>\n<td>Bolting compresses a gasket between the body and bonnet joint faces<\/td>\n<td>Internal pressure energizes a seal ring against the body and bonnet sealing arrangement<\/td>\n<td>Approved sectional drawing and design basis<\/td>\n<\/tr>\n<tr>\n<td>Low- or zero-pressure condition<\/td>\n<td>Installed bolting load establishes gasket seating<\/td>\n<td>Initial seating and correct assembly remain important before pressure energization<\/td>\n<td>Assembly procedure and defined low-pressure test scope<\/td>\n<\/tr>\n<tr>\n<td>Pressure-temperature selection<\/td>\n<td>Depends on the complete valve design, material group and rating basis<\/td>\n<td>Depends on the complete valve design, material group and rating basis<\/td>\n<td>Datasheet, applicable standard and rating documentation<\/td>\n<\/tr>\n<tr>\n<td>Thermal cycling<\/td>\n<td>Bolting, gasket and joint faces must retain an acceptable load relationship<\/td>\n<td>Seal ring, body\/bonnet surfaces and retained components must accommodate the specified cycle<\/td>\n<td>Operating cycle and design review<\/td>\n<\/tr>\n<tr>\n<td>Maintenance route<\/td>\n<td>Bolting and gasket work may be familiar, but tightening and inspection remain controlled<\/td>\n<td>Disassembly, surface inspection and seal-ring replacement can be design-specific<\/td>\n<td>Exact IOM, required tools, spares and field capability<\/td>\n<\/tr>\n<tr>\n<td>Typical procurement error<\/td>\n<td>Specifying only a pressure class and generic gasket<\/td>\n<td>Assuming \u201cself-energizing\u201d eliminates low-pressure, assembly or maintenance concerns<\/td>\n<td>Normalized supplier deviation and evidence schedule<\/td>\n<\/tr>\n<tr>\n<td>Universal winner<\/td>\n<td>No<\/td>\n<td>No<\/td>\n<td>Project-specific review and approved order documents<\/td>\n<\/tr>\n<\/tbody><\/table><\/div>\n\n<p>This table deliberately avoids a universal pressure-class crossover. A Class or PN designation alone cannot decide the bonnet construction, and a generic internet threshold should not override the project specification or the manufacturer\u2019s controlled design basis.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-27e732f4 elementor-widget elementor-widget-html\" data-id=\"27e732f4\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"what-changes-at-the-body-bonnet-joint\">What Changes at the Body\u2013Bonnet Joint?<\/h2>\n\n<h3 id=\"how-a-bolted-bonnet-joint-works\">How a bolted bonnet joint works<\/h3>\n\n<p>A bolted bonnet normally joins body and bonnet flanges with studs or bolts and a gasket between the mating faces. During controlled assembly, the bolting load compresses the gasket sufficiently to establish the required joint seal. Internal pressure then applies a separating load to the joint. The design must retain an acceptable relationship among bolting load, gasket stress, pressure load, temperature and joint stiffness throughout the specified conditions.<\/p>\n\n<p>The word \u201cbolted\u201d does not define the complete joint. A technical review may need to identify:<\/p>\n\n<ul>\n<li>body and bonnet joint geometry;<\/li>\n<li>bolting size, material specification and condition;<\/li>\n<li>gasket type, material, dimensions and replacement rule;<\/li>\n<li>joint-face finish and allowable condition;<\/li>\n<li>tightening method, sequence and lubrication controls;<\/li>\n<li>pressure and temperature cases;<\/li>\n<li>thermal-cycle and piping-load assumptions;<\/li>\n<li>examination, pressure test and maintenance requirements.<\/li>\n<\/ul>\n\n<p>Bolting torque is not a universal material property. A field value depends on the exact joint, fastener, lubricant or friction basis, gasket and procedure. This article therefore does not provide a generic torque or retightening interval.<\/p>\n\n<p>Temperature changes can affect a bolted joint through differential expansion, gasket creep or relaxation and changes in component properties. That does not mean a bolted bonnet is inherently unsuitable for demanding duty. It means the offered design and operating cycle must be evaluated together.<\/p>\n\n<h3 id=\"how-a-pressure-seal-bonnet-joint-works\">How a pressure seal bonnet joint works<\/h3>\n\n<p>In a pressure seal arrangement, the bonnet is generally located within the body opening and a seal ring acts between the bonnet and a sealing surface in the body. As internal pressure acts on the arrangement, it contributes to loading or energizing the seal. The exact geometry, initial seating method, retaining components and load path vary by design.<\/p>\n\n<p>A pressure seal review should identify:<\/p>\n\n<ul>\n<li>seal-ring geometry and component identity;<\/li>\n<li>seal-ring material specification and any facing or coating;<\/li>\n<li>body and bonnet sealing-surface requirements;<\/li>\n<li>initial assembly and seating procedure;<\/li>\n<li>retaining ring, segmented ring, yoke or other retained components where applicable;<\/li>\n<li>allowable pressure-temperature range from the controlled design basis;<\/li>\n<li>low-pressure, startup, shutdown and test conditions;<\/li>\n<li>disassembly, surface inspection and replacement procedure;<\/li>\n<li>required spares and special tooling;<\/li>\n<li>pressure and leakage test acceptance.<\/li>\n<\/ul>\n\n<p>The phrase \u201cthe higher the pressure, the tighter the seal\u201d describes the general self-energizing principle, but it is not a complete acceptance statement. Operating pressure cannot be assumed to repair a damaged seal ring, contaminated interface, unsuitable material, incorrect assembly or damaged sealing surface. Initial seating and low-pressure behavior still need a defined design and test basis.<\/p>\n\n<p>Retaining or assembly hardware should not be dismissed as unimportant merely because process pressure energizes the seal. Its precise function and load condition must be read from the approved design.<\/p>\n\n<figure data-evidence-role=\"non-evidentiary-engineering-illustration\" data-evidence-level=\"F0_UNVERIFIED\" class=\"rv-figure\" data-image-status=\"live-verified\" data-media-id=\"14277\">\n  <img loading=\"lazy\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/08\/pressure-seal-vs-bolted-bonnet-load-path.webp\" alt=\"Load path diagram for bolted bonnet preload and pressure seal bonnet internal pressure energization\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\" title=\"\">\n  <figcaption>Conceptual load paths only: initial assembly, component condition and low-pressure behavior still require a controlled design and test basis. Not a force calculation or product drawing. Engineering decision aid only; not product evidence.<\/figcaption>\n<\/figure>\n\n<h3 id=\"bonnet-joint-leakage-is-not-seat-or-stem-leakage\">Bonnet-joint leakage is not seat or stem leakage<\/h3>\n\n<p>External leakage at the body\u2013bonnet joint is one pressure-boundary concern. Leakage across a closed gate, disc or plug is internal seat leakage. Leakage around a moving stem is associated with the packing or other stem-sealing arrangement. Different design features, test methods and acceptance criteria apply.<\/p>\n\n<p>A pressure seal bonnet does not by itself establish tight shutoff, a seat leakage rate, fugitive-emission performance or stem-seal qualification. Similarly, passing a closure test does not prove that every external body joint satisfies an unrelated emission criterion. The RFQ and inspection plan should name each required result separately.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-77228a59 elementor-widget elementor-widget-html\" data-id=\"77228a59\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"pressure-and-temperature-do-not-create-a-universal-crossover-point\">Pressure and Temperature Do Not Create a Universal Crossover Point<\/h2>\n\n<p>Industry discussions often reduce this comparison to a statement such as \u201cuse bolted bonnet below one class and pressure seal above it.\u201d That shortcut leaves out several controlling variables.<\/p>\n\n<p>First, pressure class is a designation within an applicable rating system. Allowable pressure changes with material group and temperature, and the exact valve must fall within the applicable design scope. Second, startup or low-load conditions may be important even when normal operation is at high pressure. Third, valve size, joint geometry and body construction influence the loads and practical design route. Fourth, an owner specification may prescribe a construction based on plant experience, maintenance strategy or standardization.<\/p>\n\n<p>At minimum, compare these cases:<\/p>\n\n<ul>\n<li>normal operating pressure and temperature;<\/li>\n<li>maximum operating or differential pressure where relevant;<\/li>\n<li>design pressure and temperature;<\/li>\n<li>startup and shutdown conditions;<\/li>\n<li>heat-up and cool-down rates where specified;<\/li>\n<li>pressure and temperature cycles over the expected duty;<\/li>\n<li>hydrostatic or other specified test condition;<\/li>\n<li>abnormal or transient cases identified by the project.<\/li>\n<\/ul>\n\n<p>The result may be a pressure seal candidate, a bolted bonnet candidate, both constructions remaining technically open, or a hold pending data. The result should not be chosen from the product name alone.<\/p>\n\n<h3 id=\"conditions-that-require-focused-engineering-review\">Conditions that require focused engineering review<\/h3>\n\n<p>Escalate the body\u2013bonnet decision when any of the following applies:<\/p>\n\n<ul>\n<li>repeated heat-up and cool-down cycles or rapid thermal transients;<\/li>\n<li>high-energy service with serious consequences of external leakage;<\/li>\n<li>a wide change between startup and normal operating pressure;<\/li>\n<li>owner or licensor specifications mandate a bonnet construction;<\/li>\n<li>limited access for joint inspection, disassembly or component lifting;<\/li>\n<li>replacement valves must align with an existing maintenance and spare-parts system;<\/li>\n<li>the proposed material or seal arrangement is not supported across all specified cases;<\/li>\n<li>the supplier cannot provide the applicable drawing, design basis, IOM and test evidence.<\/li>\n<\/ul>\n\n<figure data-evidence-role=\"non-evidentiary-engineering-illustration\" data-evidence-level=\"F0_UNVERIFIED\" class=\"rv-figure\" data-image-status=\"live-verified\" data-media-id=\"14274\">\n  <img loading=\"lazy\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/08\/pressure-seal-bonnet-selection-data-gate.webp\" alt=\"Engineering data gate for choosing between pressure seal and bolted bonnet valve construction\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\" title=\"\">\n  <figcaption>Pressure class alone does not choose the bonnet. Service cases, valve design, standards, materials, maintenance and evidence must be reviewed together. Engineering decision aid only; not product evidence.<\/figcaption>\n<\/figure>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-366df8ae elementor-widget elementor-widget-html\" data-id=\"366df8ae\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"where-the-comparison-applies-and-where-it-does-not\">Where the Comparison Applies\u2014and Where It Does Not<\/h2>\n\n<h3 id=\"gate-valves\">Gate valves<\/h3>\n\n<p>Pressure seal and bolted bonnet constructions can appear in applicable gate-valve designs, but the bonnet label does not complete gate-valve selection. The purchaser must still confirm the isolation duty, wedge or other gate design, rising or non-rising stem architecture, seat and trim, packing, end connection and operating method.<\/p>\n\n<p>A conventional gate valve should not be promoted as a throttling solution without design-specific support. Pressure seal construction also does not prove a particular pressure rating, high-temperature capability, steam suitability or applicable API design basis. These fields require exact product evidence.<\/p>\n\n<h3 id=\"globe-valves\">Globe valves<\/h3>\n\n<p>Applicable globe-valve designs may also use bolted or pressure seal bonnets. The purchaser must separately declare whether the valve performs shutoff, intermittent throttling or another duty. Body pattern, disc or plug design, seat, guide, packing, flow direction and pressure-drop conditions remain relevant.<\/p>\n\n<p>A pressure seal globe valve is not automatically a sized control valve. Continuous regulation may require flow cases, allowable pressure drop, cavitation or flashing review, noise requirements, rangeability and actuator selection. The word \u201cglobe\u201d cannot replace those calculations.<\/p>\n\n<h3 id=\"check-valves\">Check valves<\/h3>\n\n<p>Some check-valve constructions may use a pressure seal cover or bonnet route, but applicability must be verified for the exact design. Bonnet construction does not determine opening behavior or closing dynamics.<\/p>\n\n<p>For <a href=\"https:\/\/raymonvalve.com\/check-valves\/\">industrial check valve selection<\/a>, the buyer may need normal, minimum and maximum flow or velocity; fluid density and phase; line orientation; pump or compressor relationship; reverse-flow and transient risk; permitted pressure loss; and expected cycling. A pressure seal body joint cannot prove non-slam performance, cracking pressure or installation orientation.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-a08a7532 elementor-widget elementor-widget-html\" data-id=\"a08a7532\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"failure-modes-and-what-to-verify\">Failure Modes and What to Verify<\/h2>\n\n<p>Observed body\u2013bonnet leakage should trigger a controlled safety, inspection and evidence process. The valve must be handled under the site\u2019s approved isolation, depressurization and maintenance procedures. The table below is a review aid, not a live-system repair instruction.<\/p>\n\n<div class=\"raymonvalve-table-wrap\" role=\"region\" aria-label=\"Scrollable technical table 2\" tabindex=\"0\"><table>\n<thead>\n<tr>\n<th>Observed risk or symptom<\/th>\n<th>Possible contributors<\/th>\n<th>Evidence or inspection direction<\/th>\n<th>Unsafe shortcut to avoid<\/th>\n<\/tr>\n<\/thead>\n<tbody><tr>\n<td>External leakage at a bolted joint<\/td>\n<td>loss of installed load, gasket degradation, damaged joint faces, bolting condition, thermal cycling or incorrect assembly<\/td>\n<td>joint history, bolting and gasket identity, controlled inspection, assembly records and test results<\/td>\n<td>tightening an operating joint without an approved procedure<\/td>\n<\/tr>\n<tr>\n<td>External leakage at a pressure seal joint<\/td>\n<td>seal-ring damage, contamination, surface damage, incorrect seating, unsuitable replacement part, assembly error or thermal effects<\/td>\n<td>exact IOM, seal-ring traceability, surface inspection, assembly traveler and test record<\/td>\n<td>assuming higher operating pressure will correct damage<\/td>\n<\/tr>\n<tr>\n<td>Leakage after maintenance<\/td>\n<td>wrong component, uncontrolled tightening or seating, damaged surface, omitted examination or incomplete retest<\/td>\n<td>parts verification, maintenance record, inspection hold points and post-maintenance test<\/td>\n<td>reusing a gasket or seal ring merely because it appears intact<\/td>\n<\/tr>\n<tr>\n<td>Persistent concern with no visible release<\/td>\n<td>unsuitable monitoring method, inaccessible joint, incomplete baseline or undefined acceptance criterion<\/td>\n<td>agreed examination or test method, baseline and acceptance record<\/td>\n<td>claiming perfect sealing without a defined method and limit<\/td>\n<\/tr>\n<tr>\n<td>Repeated joint intervention<\/td>\n<td>service cycle outside the assumed basis, installation load, component mismatch or incomplete root-cause review<\/td>\n<td>service history, process trend, piping\/support condition and manufacturer review<\/td>\n<td>treating repeated component replacement as proof of root cause<\/td>\n<\/tr>\n<\/tbody><\/table><\/div>\n\n<figure data-evidence-role=\"non-evidentiary-engineering-illustration\" data-evidence-level=\"F0_UNVERIFIED\" class=\"rv-figure\" data-image-status=\"live-verified\" data-media-id=\"14273\">\n  <img loading=\"lazy\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/08\/bonnet-joint-failure-mode-verification-map.webp\" alt=\"Failure mode and verification map for bolted and pressure seal valve bonnet joints\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\" title=\"\">\n  <figcaption>Possible contributors require controlled inspection and exact valve records; this diagram is not a live-system repair procedure. Engineering decision aid only; not product evidence.<\/figcaption>\n<\/figure>\n\n<h3 id=\"do-not-diagnose-from-the-construction-name-alone\">Do not diagnose from the construction name alone<\/h3>\n\n<p>A leaking bolted joint does not automatically prove that pressure seal construction is the correct replacement. A leaking pressure seal joint does not automatically prove the design principle is unsuitable. The investigation should establish the actual leak location, component identity, operating history, assembly condition, surface condition and relationship to the approved service envelope.<\/p>\n\n<p>The same discipline applies during supplier comparison. Marketing statements such as \u201cno bolt relaxation,\u201d \u201cself-tightening,\u201d \u201ceasy maintenance\u201d or an unqualified leakage promise are not acceptance evidence unless they are translated into a controlled configuration, calculation or qualification basis and a defined test result.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-80abcf82 elementor-widget elementor-widget-html\" data-id=\"80abcf82\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"maintenance-and-lifecycle-planning\">Maintenance and Lifecycle Planning<\/h2>\n\n<h3 id=\"bolted-bonnet-maintenance-questions\">Bolted bonnet maintenance questions<\/h3>\n\n<p>A bolted bonnet may offer a familiar dismantling route, but familiarity is not the same as simplicity under every site condition. Before approval, ask:<\/p>\n\n<ul>\n<li>Can the valve be safely isolated, depressurized, drained and decontaminated?<\/li>\n<li>Is there access for tooling, bolt removal and bonnet lifting?<\/li>\n<li>Is the current manufacturer IOM available for the exact model and revision?<\/li>\n<li>Are the bolting and gasket specifications traceable?<\/li>\n<li>Does the procedure define joint-face inspection and acceptance?<\/li>\n<li>Is the tightening method controlled for the actual gasket and fasteners?<\/li>\n<li>What examination and pressure test are required before return to service?<\/li>\n<\/ul>\n\n<p>Field retightening, hot bolting or online intervention can create serious hazards and should never be inferred from a general article. Such work requires site authorization, a specific engineering procedure and responsible approval.<\/p>\n\n<h3 id=\"pressure-seal-maintenance-questions\">Pressure seal maintenance questions<\/h3>\n\n<p>Pressure seal disassembly can be design-specific. The seal ring may require a defined removal method, and the body or bonnet sealing surfaces may need careful inspection and protection. Ask:<\/p>\n\n<ul>\n<li>Which retained components must be unloaded or removed, and in what sequence?<\/li>\n<li>Are special tools or lifting arrangements required?<\/li>\n<li>Is the seal ring replace-only, and what exact spare identity applies?<\/li>\n<li>What surface condition or dimensional checks govern reuse of the body and bonnet?<\/li>\n<li>How is initial seating established during reassembly?<\/li>\n<li>What low-pressure and full test sequence is required?<\/li>\n<li>Can the work be performed at site, or does the manufacturer require workshop service?<\/li>\n<\/ul>\n\n<p>Do not assume a generic pressure seal ring or procedure will fit every design.<\/p>\n\n<h3 id=\"compare-lifecycle-scope-not-a-percentage-claim\">Compare lifecycle scope, not a percentage claim<\/h3>\n\n<p>Lifecycle evaluation should include initial equipment scope, installation space, planned outage time, skill and tooling requirements, spare gaskets or seal rings, inspection effort, post-maintenance testing, handling risk and the consequence of external leakage. Without a defined service case and normalized supplier offers, a claim that one construction is a fixed percentage lighter, cheaper or more reliable is not defensible.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-0ff9f693 elementor-widget elementor-widget-html\" data-id=\"0ff9f693\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"installation-maintenance-and-handover-risk-gate\">Installation, Maintenance and Handover Risk Gate<\/h2>\n\n<p>A bonnet decision must remain workable after the valve reaches the site. Use this gate before technical acceptance or release for manufacture. It does not authorize maintenance on an operating or pressurized valve.<\/p>\n\n<div class=\"raymonvalve-table-wrap\" role=\"region\" aria-label=\"Scrollable technical table 3\" tabindex=\"0\"><table>\n<thead>\n<tr>\n<th>Installation or handover risk<\/th>\n<th>Why it can change the preliminary choice<\/th>\n<th>Verification to request<\/th>\n<th>Status if unresolved<\/th>\n<\/tr>\n<\/thead>\n<tbody><tr>\n<td>Removal and lifting envelope<\/td>\n<td>Bolting access, bonnet lift height, retained pressure-seal parts and tooling space differ by exact design<\/td>\n<td>Approved GA drawing, component weights where controlled, lifting points and maintenance envelope<\/td>\n<td><strong>HOLD \u2014 LAYOUT<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Piping load, support and alignment<\/td>\n<td>External load or distortion can affect a pressure-boundary joint independently of its bonnet label<\/td>\n<td>Project piping\/support review plus supplier installation limits<\/td>\n<td><strong>HOLD \u2014 INSTALLATION<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Isolation, draining and depressurization<\/td>\n<td>Either joint requires a site-controlled safe state before inspection or disassembly<\/td>\n<td>Exact IOM plus owner isolation, drain, vent, decontamination and permit procedure<\/td>\n<td><strong>HOLD \u2014 MAINTENANCE<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Seal and gasket spare identity<\/td>\n<td>A generic gasket or pressure seal ring may not match the supplied geometry, material condition or evidence scope<\/td>\n<td>Model- and revision-linked parts list, component identity, storage limits and replacement rule<\/td>\n<td><strong>OPEN \u2014 SPARES<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Joint condition after intervention<\/td>\n<td>Reassembly acceptance may depend on surfaces, retained parts, fasteners, seating method and a defined retest<\/td>\n<td>Inspection criteria, assembly traveler, replacement rules and post-maintenance test plan<\/td>\n<td><strong>HOLD \u2014 RETURN TO SERVICE<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Site capability and handover records<\/td>\n<td>A technically acceptable design can still be impractical if tooling, training, documents or workshop support are unavailable<\/td>\n<td>IOM, tooling list, training\/handover scope, inspection records and responsible contacts<\/td>\n<td><strong>OPEN \u2014 HANDOVER<\/strong><\/td>\n<\/tr>\n<\/tbody><\/table><\/div>\n\n<p>These statuses are review gates, not failure predictions. The owner controls site safety and isolation; the supplier controls product-specific limits and instructions; the responsible project team decides whether the complete installation and maintenance route is acceptable.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-51ac91c3 elementor-widget elementor-widget-html\" data-id=\"51ac91c3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"standards-and-testing-keep-the-roles-separate\">Standards and Testing: Keep the Roles Separate<\/h2>\n\n<p><a href=\"https:\/\/www.asme.org\/codes-standards\/find-codes-standards\/b16-34-valves-flanged-threaded-welding-end\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">ASME B16.34<\/a> provides pressure-temperature rating and broader new-valve construction context for valves within its scope. The official ASME page identifies the 2025 edition. It does not prove that a particular Raymon valve uses a specified bonnet design or complies with the standard.<\/p>\n\n<p>Current API listings identify standards that may be relevant to different valve families. API 600\u2019s current title is limited to steel gate valves with bolted bonnets; it must not be treated as automatic coverage of a pressure-seal alternative. API 623, API 602 and API 594 also require exact-edition, construction-scope, optional-requirement and project-applicability review against the purchase specification and controlled text.<\/p>\n\n<p>Testing references such as API 598 or ISO 5208 perform a different role from a valve design or rating standard. The purchaser should define the required shell or pressure-boundary test, closure or seat test, test medium, pressure, duration, acceptance criteria, witness points and records. A shell test does not establish control performance, fire qualification, fugitive-emission qualification or material compatibility.<\/p>\n\n<p>For a practical overview of how test roles should be separated, buyers can review <a href=\"https:\/\/raymonvalve.com\/valve-pressure-testing\/\">valve pressure testing<\/a> and then place the exact project requirements into the datasheet and inspection plan.<\/p>\n\n<blockquote>\n<p><strong>Standards boundary:<\/strong> An external standard can explain a general design or test scope. It cannot prove product compliance, certification or order acceptance. Those states require evidence tied to the exact offered or supplied configuration.<\/p>\n<\/blockquote>\n\n<p class=\"rv-source-note\" role=\"note\"><strong>Official source status checked 14 August 2026:<\/strong> the ASME B16.34 page identifies the 2025 edition; the <a href=\"https:\/\/www.api.org\/products-and-services\/api-monogram-and-apiqr\/latest-updates\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">API current updates<\/a> identify API 600, 14th Edition, Errata 1 and its bolted-bonnet title; and the <a href=\"https:\/\/restservice.epri.com\/publicdownload\/000000000001009701\/0\/Product\" target=\"_blank\" rel=\"noopener noreferrer nofollow\">EPRI pressure-seal maintenance guide<\/a> provides maintenance and troubleshooting context. The project must confirm the contractually applicable standard, edition, scope and acceptance criteria. These sources do not establish Raymon product design, conformity, qualification, certification or an order-specific maintenance procedure.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-6d2886d1 elementor-widget elementor-widget-html\" data-id=\"6d2886d1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"who-owns-each-technical-confirmation\">Who Owns Each Technical Confirmation?<\/h2>\n\n<p>A complete comparison makes ownership visible. \u201cSupplier to confirm\u201d cannot close a requirement the purchaser has not defined, and a purchaser requirement cannot close a field that the supplier has not tied to the exact offered valve.<\/p>\n\n<div class=\"raymonvalve-table-wrap\" role=\"region\" aria-label=\"Scrollable technical table 4\" tabindex=\"0\"><table>\n<thead>\n<tr>\n<th>Decision field<\/th>\n<th>Purchaser \/ project owner<\/th>\n<th>Valve or package supplier<\/th>\n<th>Quality \/ inspection role<\/th>\n<th>Unresolved state<\/th>\n<\/tr>\n<\/thead>\n<tbody><tr>\n<td>Service and consequence<\/td>\n<td>Define medium\/composition, pressure-temperature cases, cycles, external-release consequence and acceptance basis<\/td>\n<td>Identify limits, exclusions and missing inputs for the offered construction<\/td>\n<td>Confirm required records and witness points are specified<\/td>\n<td><strong>HOLD \u2014 DATA<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Exact valve and bonnet construction<\/td>\n<td>Define family, function, size\/class, connection and any owner mandate<\/td>\n<td>Identify model\/SKU, joint architecture, components and drawing revision<\/td>\n<td>Verify document identity and revision control<\/td>\n<td><strong>OPEN \u2014 ENTITY<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Materials and environment<\/td>\n<td>Define process composition, contaminants, cleaning, external atmosphere and project restrictions<\/td>\n<td>Provide component-level material specifications, conditions and deviations<\/td>\n<td>Verify traceability, certificates and specified examination scope<\/td>\n<td><strong>HOLD \u2014 MATERIAL REVIEW<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Rating and design basis<\/td>\n<td>Define all operating, design, startup, shutdown and test cases plus governing requirements<\/td>\n<td>Provide the applicable rating\/design basis and configuration limits without extending their scope<\/td>\n<td>Check the identity, edition, scope and acceptance route of submitted records<\/td>\n<td><strong>HOLD \u2014 DESIGN BASIS<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Assembly and maintenance<\/td>\n<td>Define isolation, access, turnaround, lifting and site capability<\/td>\n<td>Provide exact IOM, tools, inspection points, replacement rules and reassembly method<\/td>\n<td>Confirm hold points and post-maintenance records\/tests<\/td>\n<td><strong>HOLD \u2014 MAINTENANCE<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Pressure and leakage tests<\/td>\n<td>Define shell, joint, stem and seat requirements separately, including witness and records<\/td>\n<td>Provide procedures and exact tag\/order results for the offered valve<\/td>\n<td>Verify medium, pressure, duration, acceptance, identity and witness status<\/td>\n<td><strong>HOLD \u2014 TEST EVIDENCE<\/strong><\/td>\n<\/tr>\n<tr>\n<td>Order documents and deviations<\/td>\n<td>Define ITP, MTC, NDT\/PMI if applicable, marking, language and dossier requirements<\/td>\n<td>Issue a document register and explicit deviation\/exclusion schedule<\/td>\n<td>Track approval, release and order-specific record completion<\/td>\n<td><strong>OPEN \u2014 DOCUMENTS<\/strong><\/td>\n<\/tr>\n<\/tbody><\/table><\/div>\n\n<p>This matrix does not assign legal or contractual responsibility. The purchase specification, approved datasheet and project quality plan remain controlling. Its purpose is to stop unowned assumptions from becoming technical acceptance.<\/p>\n\n<figure data-evidence-role=\"non-evidentiary-engineering-illustration\" data-evidence-level=\"F0_UNVERIFIED\" class=\"rv-figure\" data-image-status=\"live-verified\" data-media-id=\"14275\">\n  <img loading=\"lazy\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/08\/pressure-seal-bonnet-supplier-evidence-chain.webp\" alt=\"Supplier evidence chain for pressure seal or bolted bonnet valve approval\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\" title=\"\">\n  <figcaption>A bonnet label or standard name is not approval evidence. The offered identity, design basis, materials, IOM, tests, spares and deviations must align. Engineering decision aid only; not product evidence.<\/figcaption>\n<\/figure>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b3a887c1 elementor-widget elementor-widget-html\" data-id=\"b3a887c1\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"supplier-evidence-matrix\">Supplier Evidence Matrix<\/h2>\n\n<div class=\"raymonvalve-table-wrap\" role=\"region\" aria-label=\"Scrollable technical table 5\" tabindex=\"0\"><table>\n<thead>\n<tr>\n<th>Evidence item<\/th>\n<th>Why the buyer needs it<\/th>\n<th>Minimum identity and scope check<\/th>\n<\/tr>\n<\/thead>\n<tbody><tr>\n<td>Approved sectional or GA drawing<\/td>\n<td>Confirms bonnet architecture, joint components and maintenance envelope<\/td>\n<td>Valve tag\/model, revision, status and offered configuration<\/td>\n<\/tr>\n<tr>\n<td>Datasheet and design basis<\/td>\n<td>Defines pressure-temperature cases and applicable standards<\/td>\n<td>Project identity, cases, editions and approved deviations<\/td>\n<\/tr>\n<tr>\n<td>Component material schedule or BOM<\/td>\n<td>Identifies body, bonnet, bolting, gasket or seal ring, stem, packing and trim<\/td>\n<td>Component-level grades\/specifications and traceability scope<\/td>\n<\/tr>\n<tr>\n<td>Pressure-temperature rating basis<\/td>\n<td>Prevents selection by nominal class alone<\/td>\n<td>Material group, size\/class and applicable code basis<\/td>\n<\/tr>\n<tr>\n<td>Assembly and IOM procedure<\/td>\n<td>Controls installation, disassembly, inspection and reassembly<\/td>\n<td>Exact model\/design revision, tools and replacement rules<\/td>\n<\/tr>\n<tr>\n<td>Inspection and test plan<\/td>\n<td>Defines hold points and acceptance<\/td>\n<td>Pressure-boundary, closure and functional tests kept distinct<\/td>\n<\/tr>\n<tr>\n<td>Pressure or leakage test record<\/td>\n<td>Documents the supplied tag or order result<\/td>\n<td>Serial\/tag, procedure, medium, pressure, duration, acceptance and witness<\/td>\n<\/tr>\n<tr>\n<td>Spare-parts list<\/td>\n<td>Supports planned maintenance<\/td>\n<td>Exact gasket, seal ring, bolting and consumable identity<\/td>\n<\/tr>\n<tr>\n<td>Technical deviation schedule<\/td>\n<td>Prevents silent construction substitutions<\/td>\n<td>Every exception closed by the responsible parties before release<\/td>\n<\/tr>\n<\/tbody><\/table><\/div>\n\n<p>A family brochure or an unrelated test certificate may support discovery, but it should not replace exact offered-valve evidence.<\/p>\n\n<p>For a broader framework covering inspection plans, hold points, witness points and traceable evidence, use the <a href=\"https:\/\/raymonvalve.com\/valve-inspection\/\">Industrial Valve Inspection and ITP Guide<\/a>.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-c1267a10 elementor-widget elementor-widget-html\" data-id=\"c1267a10\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"rfq-checklist-for-a-defensible-comparison\">RFQ Checklist for a Defensible Comparison<\/h2>\n\n<h3 id=\"common-project-inputs\">Common project inputs<\/h3>\n\n<p>Send suppliers the same controlled set of data:<\/p>\n\n<ul>\n<li>valve family, type, tag and function;<\/li>\n<li>DN\/NPS and PN\/Class;<\/li>\n<li>normal, design, startup and test pressure-temperature cases;<\/li>\n<li>medium, composition, phase, contaminants and solids;<\/li>\n<li>body, bonnet, trim, seat, stem, packing and joint-seal requirements;<\/li>\n<li>end connection, flange facing or end preparation and governing standard;<\/li>\n<li>manual, gear or actuated operation and expected cycling;<\/li>\n<li>required design, rating, test and inspection standards with editions;<\/li>\n<li>bonnet preference or owner mandate, if one exists;<\/li>\n<li>external joint, stem and seat leakage requirements stated separately;<\/li>\n<li>quantity, destination and project identity;<\/li>\n<li>inspection, documentation, witness and final-dossier requirements;<\/li>\n<li>maintenance access, spare parts, lifting and IOM requirements.<\/li>\n<\/ul>\n\n<h3 id=\"gate-valve-additions\">Gate-valve additions<\/h3>\n\n<p>State the isolation duty, wedge\/slab\/knife or other approved design route, stem architecture, bidirectional requirement where applicable, packing or emission requirement, solids risk and operator inputs. Do not request a pressure seal gate valve as a complete specification without those fields.<\/p>\n\n<h3 id=\"globe-valve-additions\">Globe-valve additions<\/h3>\n\n<p>State the body pattern, shutoff versus throttling duty, flow and pressure-drop cases if regulation is intended, required flow direction where applicable, disc or plug and trim requirements, packing and actuation. A bonnet comparison cannot size a regulating valve.<\/p>\n\n<h3 id=\"check-valve-additions\">Check-valve additions<\/h3>\n\n<p>State flow or velocity cases, fluid density and phase, line orientation, pump or compressor relationship, reverse-flow or transient concern, allowable pressure loss, closing objective, pulsating flow and cycling. Do not infer dynamic performance from the cover or bonnet construction.<\/p>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-4b055416 elementor-widget elementor-widget-html\" data-id=\"4b055416\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"eight-step-decision-path\">Eight-Step Decision Path<\/h2>\n\n<ol>\n<li><strong>Confirm the valve function and family.<\/strong> Separate isolation, regulation and non-return duties.<\/li>\n<li><strong>Freeze all pressure-temperature cases.<\/strong> Include startup, shutdown, cycling and test conditions\u2014not only normal operation.<\/li>\n<li><strong>Identify the governing requirements.<\/strong> Record the project code, valve standard and edition, owner specification and approved deviations.<\/li>\n<li><strong>Review an actual offered design.<\/strong> Compare body\u2013bonnet joint geometry, materials and maintenance route from controlled drawings.<\/li>\n<li><strong>Check every sealing component.<\/strong> Do not reduce the review to <code>metal gasket<\/code>, <code>graphite<\/code> or another material label.<\/li>\n<li><strong>Define inspection and test acceptance.<\/strong> Keep body-joint, stem and seat leakage evidence separate.<\/li>\n<li><strong>Normalize supplier offers.<\/strong> Compare inclusions, exceptions, spares, tools, documents and witness points on the same basis.<\/li>\n<li><strong>Close open items before approval.<\/strong> Final construction belongs in the approved datasheet, drawing, deviation record and purchase order.<\/li>\n<\/ol>\n\n<p>If the process cases, applicable design basis or evidence route remain unresolved, return <strong>HOLD \u2014 DATA<\/strong> rather than selecting from a generic pressure-class rule.<\/p>\n\n<h3 id=\"illustrative-evidence-gap-decision-path\">Illustrative evidence-gap decision path<\/h3>\n\n<p>The following example shows how a provisional result can change as information becomes controlled. It is product-neutral and does not recommend a construction for a named medium, plant or Raymon product.<\/p>\n\n<div class=\"raymonvalve-table-wrap\" role=\"region\" aria-label=\"Scrollable technical table 6\" tabindex=\"0\"><table>\n<thead>\n<tr>\n<th>Review point<\/th>\n<th>Information available<\/th>\n<th>Provisional outcome<\/th>\n<th>Why<\/th>\n<\/tr>\n<\/thead>\n<tbody><tr>\n<td>Initial inquiry<\/td>\n<td>Pressure class, size and \u201chigh-pressure service\u201d only<\/td>\n<td><strong>HOLD \u2014 DATA<\/strong><\/td>\n<td>Valve function, complete pressure-temperature cases, cycles, materials, maintenance route and acceptance evidence are incomplete<\/td>\n<\/tr>\n<tr>\n<td>Project basis completed<\/td>\n<td>Function, service cases, owner requirements, joint leakage acceptance and maintenance constraints are defined<\/td>\n<td><strong>BOTH OPEN<\/strong><\/td>\n<td>The requirement can be compared, but neither offered construction has been verified<\/td>\n<\/tr>\n<tr>\n<td>Technical offers received<\/td>\n<td>Exact bolted and pressure seal arrangements, drawings, materials, limits, IOMs, tests and deviations are supplied<\/td>\n<td><strong>BOTH OPEN<\/strong> or one <strong>CANDIDATE<\/strong><\/td>\n<td>Each offer is normalized against the same project basis; a class designation or bonnet label does not close the decision<\/td>\n<\/tr>\n<tr>\n<td>One offer has a controlling gap<\/td>\n<td>A rating, material, assembly, low-pressure, test or maintainability field is unsupported<\/td>\n<td>That offer returns to <strong>HOLD<\/strong><\/td>\n<td>Unrelated certificates, brochure wording or higher operating pressure cannot offset missing controlling evidence<\/td>\n<\/tr>\n<tr>\n<td>Technical bid normalized<\/td>\n<td>One candidate matches the project inputs and its documents and deviations are accepted by the responsible parties<\/td>\n<td><strong>CANDIDATE FOR PROJECT APPROVAL<\/strong><\/td>\n<td>Final approval still belongs to the exact order-specific decision process<\/td>\n<\/tr>\n<\/tbody><\/table><\/div>\n\n<p>The outcome is reversible. A changed startup case, new thermal-cycle information, a supplier deviation, a drawing revision or an evidence-scope mismatch can move a candidate back to <strong>BOTH OPEN<\/strong> or <strong>HOLD \u2014 DATA<\/strong>.<\/p>\n\n<figure data-evidence-role=\"non-evidentiary-engineering-illustration\" data-evidence-level=\"F0_UNVERIFIED\" class=\"rv-figure\" data-image-status=\"live-verified\" data-media-id=\"14278\">\n  <img loading=\"lazy\" src=\"https:\/\/raymonvalve.com\/wp-content\/uploads\/2026\/08\/pressure-seal-vs-bolted-bonnet-rfq-decision-path.webp\" alt=\"Eight-step RFQ decision path for comparing pressure seal and bolted bonnet valves\" width=\"1200\" height=\"900\" loading=\"lazy\" decoding=\"async\" title=\"\">\n  <figcaption>A defensible comparison starts with service data and ends with approved drawings, deviations and order documents\u2014not a generic bonnet preference. Engineering decision aid only; not product evidence.<\/figcaption>\n<\/figure>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-bd3af66d elementor-widget elementor-widget-html\" data-id=\"bd3af66d\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"frequently-asked-questions\">Frequently Asked Questions<\/h2>\n\n<div class=\"rv-faq-list\">\n<details class=\"rv-faq-item\">\n  <summary id=\"what-is-the-main-difference-between-a-pressure-seal-bonnet-and-a-bolted-bonnet\">What is the main difference between a pressure seal bonnet and a bolted bonnet?<\/summary>\n  <div class=\"rv-faq-answer\"><p>A bolted bonnet generally uses installed bolting load to compress a gasket at the body\u2013bonnet joint. A pressure seal bonnet uses internal pressure to energize a seal ring within the body\u2013bonnet arrangement. The exact geometry, retained components and initial seating method are design-specific.<\/p><\/div>\n<\/details>\n<details class=\"rv-faq-item\">\n  <summary id=\"is-a-pressure-seal-bonnet-the-preferred-choice-for-every-high-pressure-service\">Is a pressure seal bonnet the preferred choice for every high-pressure service?<\/summary>\n  <div class=\"rv-faq-answer\"><p>No. It may be a strong candidate for a correctly engineered demanding pressure-temperature duty, but final selection also depends on startup and cycling conditions, valve family and size, materials, project requirements, maintenance access, testing and configuration-specific evidence.<\/p><\/div>\n<\/details>\n<details class=\"rv-faq-item\">\n  <summary id=\"does-a-pressure-seal-bonnet-leak-at-low-pressure\">Does a pressure seal bonnet leak at low pressure?<\/summary>\n  <div class=\"rv-faq-answer\"><p>That cannot be answered safely from the design name alone. Low-pressure performance depends on the exact geometry, initial seating, seal-ring condition, assembly procedure and test acceptance. The supplier should document the applicable basis rather than relying on a slogan about higher pressure.<\/p><\/div>\n<\/details>\n<details class=\"rv-faq-item\">\n  <summary id=\"can-bonnet-type-determine-the-valve-pressure-class\">Can bonnet type determine the valve pressure class?<\/summary>\n  <div class=\"rv-faq-answer\"><p>No. Pressure class and allowable pressure at temperature must follow the applicable design and rating basis for the exact valve, material group and size. Bonnet construction is one design field, not the complete rating decision.<\/p><\/div>\n<\/details>\n<details class=\"rv-faq-item\">\n  <summary id=\"which-valve-types-can-use-pressure-seal-construction\">Which valve types can use pressure seal construction?<\/summary>\n  <div class=\"rv-faq-answer\"><p>It can appear in applicable Gate, Globe and some Check designs. Availability and suitability must be confirmed for the exact product entity. Bonnet type must not be inherited across an entire valve family.<\/p><\/div>\n<\/details>\n<details class=\"rv-faq-item\">\n  <summary id=\"is-a-bolted-bonnet-easier-to-maintain\">Is a bolted bonnet easier to maintain?<\/summary>\n  <div class=\"rv-faq-answer\"><p>Its bolting and gasket workflow may be more familiar to some sites, but safe maintenance still requires isolation, the exact IOM, access and lifting planning, correct parts, controlled assembly, inspection and retesting. Ease of maintenance is project- and design-specific.<\/p><\/div>\n<\/details>\n<details class=\"rv-faq-item\">\n  <summary id=\"what-documents-should-be-requested-with-a-pressure-seal-valve\">What documents should be requested with a pressure seal valve?<\/summary>\n  <div class=\"rv-faq-answer\"><p>Request the approved sectional and GA drawings, datasheet and design basis, component material schedule, pressure-temperature rating basis, IOM, inspection and test plan, exact test records, spare-parts list and closed technical-deviation schedule.<\/p><\/div>\n<\/details>\n<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-b214243c elementor-widget elementor-widget-html\" data-id=\"b214243c\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"html.default\">\n\t\t\t\t\t<h2 id=\"engineering-note\">Engineering Note<\/h2>\n\n<p>This article is owned as organization-level technical content by the <strong>Raymon Valve Technical Content Team<\/strong>. It supports preliminary comparison, risk identification, RFQ preparation and technical-bid normalization. It does not claim review or authorship by a named professional engineer.<\/p>\n\n<p>No order-specific datasheet, approved drawing, calculation, material record, qualification report, production test record, certificate or approved deviation was used to select a valve in this article. Final construction, pressure-temperature rating, component materials, joint acceptance, actuation, inspection, documentation and service approval require the complete project specification and evidence for the exact offered valve.<\/p>\n\n<aside class=\"rv-owner-links\" data-master-region=\"owner-links\" aria-label=\"Related Raymon Valve resources\">\n  <strong>Related engineering and commercial routes<\/strong>\n  <ul>\n    <li><a href=\"https:\/\/raymonvalve.com\/product\/pressure-seal-gate-valve\/\">Pressure Seal Gate Valve product overview<\/a><\/li>\n    <li><a href=\"https:\/\/raymonvalve.com\/product\/pressure-seal-globe-valve\/\">Pressure Seal Globe Valve product overview<\/a><\/li>\n    <li><a href=\"https:\/\/raymonvalve.com\/gate-valves\/\">Industrial Gate Valves<\/a><\/li>\n    <li><a href=\"https:\/\/raymonvalve.com\/globe-valves\/\">Globe Valve Designs<\/a><\/li>\n    <li><a href=\"https:\/\/raymonvalve.com\/check-valves\/\">Industrial Check Valves<\/a><\/li>\n    <li><a href=\"https:\/\/raymonvalve.com\/valve-pressure-testing\/\">Valve Pressure Testing<\/a><\/li>\n  <\/ul>\n<\/aside>\n\n<section class=\"rv-cta\" data-master-region=\"owner-links\" aria-labelledby=\"request-bonnet-construction-review\"><h2 id=\"request-bonnet-construction-review\">Request Bonnet Construction Review<\/h2>\n<p>For a preliminary comparison, <a href=\"https:\/\/raymonvalve.com\/contact\/\">submit your valve datasheet and project requirements<\/a> in five groups:<\/p>\n<ol>\n<li><strong>Function and service:<\/strong> valve family, isolation\/regulation\/non-return duty, medium and composition, phase, contaminants, solids and consequence of external leakage.<\/li>\n<li><strong>Pressure-temperature cases:<\/strong> normal, design, startup, shutdown, upset and test conditions; differential pressure where relevant; heat-up\/cool-down rate and expected cycles.<\/li>\n<li><strong>Valve and joint definition:<\/strong> DN\/NPS, PN\/Class, end connection, body pattern, proposed bonnet construction, joint components and component-level material requirements.<\/li>\n<li><strong>Operation and maintenance:<\/strong> manual\/gear\/actuated route, expected cycling, installation envelope, lifting and tooling limits, isolation strategy, site capability and spare-parts plan.<\/li>\n<li><strong>Quality and project scope:<\/strong> standards and editions, separate joint\/stem\/seat test requirements, ITP, witness points, drawings, calculations where required, MTC\/NDT\/PMI scope, IOM, deviation schedule, quantity and destination.<\/li>\n<\/ol>\n<p>Raymon Valve can review whether the submitted information is sufficient to compare bolted and pressure seal candidates and identify open supplier-evidence fields. The review does not promise final selection, pressure-temperature rating, material compatibility, compliance, certification, delivery or service suitability before the complete project specification and exact offered-valve evidence are accepted by the responsible parties.<\/p>\n\n<\/section>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/article>\n\t\t\t\t<\/div>\n\t\t","protected":false},"excerpt":{"rendered":"<p>Compare pressure seal and bolted bonnet valve designs by sealing mechanism, service conditions, maintenance risks, evidence and RFQ requirements.<\/p>","protected":false},"author":1,"featured_media":14276,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[1],"tags":[],"class_list":["post-14218","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/posts\/14218","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/comments?post=14218"}],"version-history":[{"count":5,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/posts\/14218\/revisions"}],"predecessor-version":[{"id":14279,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/posts\/14218\/revisions\/14279"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/media\/14276"}],"wp:attachment":[{"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/media?parent=14218"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/categories?post=14218"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/raymonvalve.com\/fr\/wp-json\/wp\/v2\/tags?post=14218"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}