{"id":1406,"date":"2026-10-20T00:16:11","date_gmt":"2026-10-20T00:16:11","guid":{"rendered":"https:\/\/wdlvalve.com\/?p=1406"},"modified":"2026-10-20T00:16:11","modified_gmt":"2026-10-20T00:16:11","slug":"api-594-10th-edition-check-valves","status":"publish","type":"post","link":"https:\/\/wdlvalve.com\/vi\/api-594-10th-edition-check-valves\/","title":{"rendered":"API 594 10th Edition Check Valves: Buyer Guide"},"content":{"rendered":"<article style=\"max-width:1100px;margin:0 auto;color:#243746;font-family:Arial,Helvetica,sans-serif;font-size:16px;line-height:1.75;\">\n<header style=\"padding:22px 24px;margin-bottom:28px;border-left:5px solid #1378ae;background:#f3f8fb;\">\n<p style=\"margin:0 0 10px;\"><strong>C\u00e2u tr\u1ea3 l\u1eddi tr\u1ef1c ti\u1ebfp:<\/strong> API 594 10th Edition check valves should be specified by valve type, body style, pressure class, materials, end connection, installation position and required testing. As of October 2026, API lists Errata 1 for the 10th edition, so buyers should use a controlled copy of the standard and include the applicable edition and errata in the purchase order.<\/p>\n<p style=\"margin:0;\"><strong>Published:<\/strong> October 20, 2026 | <strong>T\u00e1c gi\u1ea3:<\/strong> Wong WP, Gi\u00e1m \u0111\u1ed1c Kinh doanh, C\u00f4ng ty TNHH Van WDL H\u1ea1 M\u00f4n.<\/p>\n<\/header>\n<h2 style=\"color:#123a5a;\">What changed in October 2026?<\/h2>\n<ul>\n<li>API published <a href=\"https:\/\/www.api.org\/products-and-services\/api-monogram-and-apiqr\/latest-updates\" target=\"_blank\" rel=\"noopener\">Errata 1 for API 594, 10th Edition<\/a> in October 2026.<\/li>\n<li>This guide separates the standard designation from project-specific requirements such as sour service, chloride exposure, low temperature and water-hammer control.<\/li>\n<li>The RFQ checklist below was added to help buyers compare technically equivalent offers.<\/li>\n<\/ul>\n<figure style=\"margin:28px auto;text-align:center;\">\n<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/wdlvalve.com\/wp-content\/uploads\/2026\/09\/\u6b62\u56de\u9600-\u4fee\u56fe.png\" alt=\"API 6D swing check valve considered for an API 594 10th Edition check valve project\" width=\"500\" height=\"500\" style=\"max-width:100%;height:auto;\"><figcaption style=\"font-size:14px;color:#526473;\">Representative WDL swing check valve. The purchase specification determines whether API 594, API 6D, BS 1868 or another standard applies.<\/figcaption><\/figure>\n<h2 style=\"color:#123a5a;\">What does API 594 10th Edition cover?<\/h2>\n<p>API 594 covers check valves with flanged, lug, wafer and butt-welding end configurations. The standard addresses design, materials, dimensions, pressure-temperature ratings, inspection, examination and testing. It does not replace the purchaser&#8217;s datasheet. The datasheet still has to define the fluid, operating envelope, allowable leakage, installation orientation and any supplementary examination.<\/p>\n<p>A product described only as an \u201cAPI check valve\u201d is not sufficiently specified. State <strong>API 594, 10th Edition, including applicable errata<\/strong>, then identify the required valve pattern and project exceptions. If the pipeline specification instead requires API 6D or BS 1868, that requirement should remain explicit. WDL&#8217;s <a href=\"https:\/\/wdlvalve.com\/vi\/product\/van-mot-chieu-xoay-api-6d\/\">API 6D \/ BS 1868 flanged swing check valve<\/a> is one example of a pipeline check valve supplied to a different design basis.<\/p>\n<h2 style=\"color:#123a5a;\">Which check valve design should a buyer choose?<\/h2>\n<p>The right design is the one that closes reliably at the expected flow conditions without unacceptable pressure loss or surge. A compact wafer valve can reduce weight and installation length. A flanged swing check valve offers a familiar, serviceable arrangement. Axial or nozzle-style designs may be considered where rapid closure and surge control are dominant requirements. Do not select by nominal size alone.<\/p>\n<div style=\"width:100%;overflow-x:auto;-webkit-overflow-scrolling:touch;margin:24px 0 30px;\">\n<table style=\"width:100%;min-width:820px;border:1px solid #000!important;border-collapse:collapse;background:#fff;\" border=\"1\" rules=\"all\" cellspacing=\"0\" cellpadding=\"0\">\n<thead>\n<tr>\n<th style=\"padding:11px;border:1px solid #000!important;background:#eaf3f8;text-align:left;\">Design question<\/th>\n<th style=\"padding:11px;border:1px solid #000!important;background:#eaf3f8;text-align:left;\">Why it matters<\/th>\n<th style=\"padding:11px;border:1px solid #000!important;background:#eaf3f8;text-align:left;\">What the RFQ should state<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"padding:11px;border:1px solid #000!important;\">Body and end style<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Controls face-to-face length, piping loads and removal space<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Wafer, lug, flanged or butt-weld; mating flange standard<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:11px;border:1px solid #000!important;\">Closure behavior<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Affects slam, pressure surge and pump protection<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Normal\/minimum flow, velocity, reverse-flow event and transient study data<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:11px;border:1px solid #000!important;\">Installation<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Some mechanisms depend on gravity or a defined flow direction<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Horizontal or vertical line, upward\/downward flow and available straight run<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:11px;border:1px solid #000!important;\">Seat performance<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">\u201cNon-return\u201d does not automatically mean bubble-tight isolation<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Test medium, test pressure and allowable leakage<\/td>\n<\/tr>\n<tr>\n<td style=\"padding:11px;border:1px solid #000!important;\">Maintenance access<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Influences total lifecycle cost<\/td>\n<td style=\"padding:11px;border:1px solid #000!important;\">Removability, inspection access, spare parts and lifting limits<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2 style=\"color:#123a5a;\">How should materials be selected?<\/h2>\n<p>Body material is only the first decision. Check the disc or plates, hinge or spring, shaft, pins, seat surfaces, bolting and any non-metallic parts. Carbon steel can suit many hydrocarbon and utility services. Stainless steel, duplex stainless steel, nickel alloys or nickel-aluminum bronze may be considered when corrosion, chlorides or seawater change the risk. The final selection depends on fluid composition, water content, temperature, velocity and shutdown conditions.<\/p>\n<p>For chloride service, compare localized corrosion resistance and crevice geometry rather than relying on a generic \u201cstainless steel\u201d description. For sour service, identify the applicable material-control requirements in the project specification. For low-temperature service, state the design minimum metal temperature and impact-test requirements.<\/p>\n<figure style=\"margin:28px auto;text-align:center;\">\n<a href=\"https:\/\/wdlvalve.com\/vi\/product\/duplex-check-valve\/\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/wdlvalve.com\/wp-content\/uploads\/2026\/09\/DM_20250821083912_020.jpeg\" alt=\"Duplex check valve material option for API 594 10th Edition check valve specifications\" width=\"257\" height=\"257\" style=\"max-width:100%;height:auto;\"><\/a><figcaption style=\"font-size:14px;color:#526473;\">WDL duplex check valve. Alloy selection must be confirmed against the actual fluid and temperature.<\/figcaption><\/figure>\n<h2 style=\"color:#123a5a;\">What inspection and testing information belongs in the purchase order?<\/h2>\n<p>State the inspection and pressure-test standard, acceptance criteria, witness points and documentation before the order is placed. API 594 defines product requirements, while other referenced standards and the project specification may govern pressure testing, flange dimensions, pressure-temperature ratings, material certification or non-destructive examination. <a href=\"https:\/\/www.asme.org\/codes-standards\/find-codes-standards\/b16-34-valves-flanged-threaded-welding-end\/2017\/pdf\" target=\"_blank\" rel=\"noopener\">ASME B16.34<\/a>, for example, covers pressure-temperature ratings and other construction requirements for applicable valve materials and end types.<\/p>\n<ul>\n<li>Material certificates and heat-number traceability<\/li>\n<li>Shell and seat test method, pressure, duration and acceptance<\/li>\n<li>Visual, dimensional and functional inspection<\/li>\n<li>NDE extent and acceptance criteria when required<\/li>\n<li>Coating, preservation and packing requirements<\/li>\n<li>Final drawings, data books and spare-parts list<\/li>\n<\/ul>\n<h2 style=\"color:#123a5a;\">Can an API 594 check valve be used as an isolation valve?<\/h2>\n<p>No. A check valve is a non-return device, not a positive isolation valve. Backpressure, contamination, disc position and seat condition can allow reverse leakage. Use dedicated block valves and the project&#8217;s isolation procedure when personnel safety, equipment entry or line breaking is involved. See WDL&#8217;s detailed guide: <a href=\"https:\/\/wdlvalve.com\/vi\/van-mot-chieu-co-the-duoc-su-dung-lam-van-cach-ly-dau-va-khi-khong\/\">Van m\u1ed9t chi\u1ec1u c\u00f3 th\u1ec3 \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng l\u00e0m van c\u00e1ch ly trong c\u00e1c \u0111\u01b0\u1eddng \u1ed1ng d\u1eabn d\u1ea7u v\u00e0 kh\u00ed \u0111\u1ed1t kh\u00f4ng?<\/a><\/p>\n<h2 style=\"color:#123a5a;\">API 594 check valve RFQ checklist<\/h2>\n<ol>\n<li>Applicable standard, edition and errata<\/li>\n<li>Valve pattern, body style, size and pressure class<\/li>\n<li>Design and maximum\/minimum operating pressure and temperature<\/li>\n<li>Fluid composition, solids, chlorides, sour components and water content<\/li>\n<li>Line orientation, flow direction and normal\/minimum flow rate<\/li>\n<li>Body, trim, seat, spring and bolting materials<\/li>\n<li>End connection, facing and face-to-face requirement<\/li>\n<li>Required closure behavior or transient-analysis constraints<\/li>\n<li>Inspection, testing, certification and witness requirements<\/li>\n<li>Coating, preservation, documentation and spare parts<\/li>\n<\/ol>\n<h2 style=\"color:#123a5a;\">Frequently asked questions about API 594 10th Edition check valves<\/h2>\n<h3 style=\"color:#234f6d;\">Is API 594 10th Edition the current edition?<\/h3>\n<p>API&#8217;s latest-updates page lists API 594 10th Edition and Errata 1 dated October 2026. Buyers should verify the controlled standard and contract requirements at the time of purchase.<\/p>\n<h3 style=\"color:#234f6d;\">Does API 594 guarantee zero reverse leakage?<\/h3>\n<p>No. Leakage acceptance depends on the specified design, seat construction and test criteria. State the required leakage rate and test conditions in the RFQ.<\/p>\n<h3 style=\"color:#234f6d;\">Are swing check valves covered by every API 594 purchase specification?<\/h3>\n<p>No. The purchaser must identify the required pattern and standard. Some pipeline swing check valves are specified to API 6D or BS 1868 instead.<\/p>\n<h3 style=\"color:#234f6d;\">What data helps prevent check valve slam?<\/h3>\n<p>Provide minimum, normal and maximum flow, line velocity, pump trip scenario, downstream pressure and pipe-system transient information. A nominal size and pressure class are not enough.<\/p>\n<h3 style=\"color:#234f6d;\">Can WDL supply corrosion-resistant check valves?<\/h3>\n<p>WDL Valve offers check valves in stainless steel, duplex, nickel alloys, titanium and NAB C95800. Suitability must be confirmed from the complete service data and project specification.<\/p>\n<div style=\"margin-top:32px;padding:22px;border:1px solid #1378ae;background:#eef6fa;\">\n<h2 style=\"margin-top:0;color:#123a5a;\">Request a technical review<\/h2>\n<p>Send the valve datasheet, line class, fluid composition, operating envelope and testing requirements to WDL Valve. Our team will review the information before preparing an offer.<\/p>\n<p style=\"margin-bottom:0;\"><a href=\"https:\/\/wdlvalve.com\/vi\/lien-he-voi-chung-toi\/\" style=\"display:inline-block;padding:11px 18px;background:#1268a8;color:#fff;text-decoration:none;border-radius:3px;\">Discuss Your Check Valve RFQ<\/a><\/p>\n<\/div>\n<footer style=\"margin-top:30px;padding-top:18px;border-top:1px solid #ccd6dd;font-size:14px;color:#526473;\">\n<p><strong>About the author:<\/strong> <a href=\"https:\/\/wdlvalve.com\/vi\/about-us\/\">Wong WP<\/a> is Sales Manager at Xiamen WDL Valve Co., Ltd. and works with industrial valve inquiries covering oil and gas, chemical, water and marine applications.<\/p>\n<p><em>Ghi ch\u00fa k\u1ef9 thu\u1eadt:<\/em> This article is a purchasing guide, not a substitute for the licensed standard, approved project specification or professional engineering review.<\/p>\n<\/footer>\n<\/article>","protected":false},"excerpt":{"rendered":"<p>A practical buyer guide to API 594 10th Edition check valves, including valve selection, materials, testing and RFQ data.<\/p>","protected":false},"author":1,"featured_media":870,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_kad_post_transparent":"","_kad_post_title":"","_kad_post_layout":"","_kad_post_sidebar_id":"","_kad_post_content_style":"","_kad_post_vertical_padding":"","_kad_post_feature":"","_kad_post_feature_position":"","_kad_post_header":false,"_kad_post_footer":false,"_kad_post_classname":"","footnotes":""},"categories":[52],"tags":[],"class_list":["post-1406","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"_links":{"self":[{"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/posts\/1406","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/comments?post=1406"}],"version-history":[{"count":1,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/posts\/1406\/revisions"}],"predecessor-version":[{"id":1410,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/posts\/1406\/revisions\/1410"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/media\/870"}],"wp:attachment":[{"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/media?parent=1406"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/categories?post=1406"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wdlvalve.com\/vi\/wp-json\/wp\/v2\/tags?post=1406"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}