{"id":69669,"date":"2026-05-17T17:27:31","date_gmt":"2026-05-17T17:27:31","guid":{"rendered":"https:\/\/evgroupchina.com\/encyclopedia-of-metal\/api-st-609\/"},"modified":"2026-05-19T15:30:20","modified_gmt":"2026-05-19T15:30:20","slug":"api-st-609","status":"publish","type":"wiki","link":"https:\/\/evgroupchina.com\/en\/encyclopedia-of-metal\/api-st-609\/","title":{"rendered":"API St 609"},"content":{"rendered":"<h2>Technical Standards and Scope of API 609<\/h2>\n<p>The international standard API 609 defines engineering requirements for the design, material execution, dimensional characteristics, as well as pressure and temperature ratings for butterfly valves. The document regulates inspection and acceptance testing protocols for products manufactured from gray and ductile iron, bronze, carbon and stainless steels, nickel alloys, and other specialized materials supplied by EV Group China.<\/p>\n<p>When ordering API-monogrammed products manufactured at API-certified production facilities, the requirements set forth in Annex A of this standard are strictly observed.<\/p>\n<p>The standard classifies butterfly valves into two main categories:<\/p>\n<ul>\n<li><strong>Category A:<\/strong> Valves with a Cold Working Pressure (CWP) rating, equipped with a concentric disc and seat. The product range covers sizes from NPS 2 to NPS 48 for products designed for flange connections according to ASME Class 125 or Class 150 standards.<\/li>\n<li><strong>Category B:<\/strong> Valves complying with ASME pressure\/temperature classes, featuring an offset seat and an eccentric or concentric disc design. It is permitted for the seat pressure rating to be lower than the body pressure rating.<\/li>\n<\/ul>\n<h3>Size Ranges for Category B Valves<\/h3>\n<table class=\"table table-bordered table-hover\">\n<thead>\n<tr>\n<th>Design Type<\/th>\n<th>Pressure Class<\/th>\n<th>Size Range (NPS)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Wafer and Lug<\/td>\n<td>150<\/td>\n<td>3 to 48<\/td>\n<\/tr>\n<tr>\n<td>Lug and Wafer<\/td>\n<td>300 and 600<\/td>\n<td>3 to 48<\/td>\n<\/tr>\n<tr>\n<td>Double Flanged (Long Pattern)<\/td>\n<td>150, 300, 600<\/td>\n<td>3 to 36<\/td>\n<\/tr>\n<tr>\n<td>Double Flanged (Short Pattern)<\/td>\n<td>150, 300<\/td>\n<td>3 to 48<\/td>\n<\/tr>\n<tr>\n<td>Double Flanged (Short Pattern)<\/td>\n<td>600<\/td>\n<td>3 to 24<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Technical ordering requirements provided by the buyer are detailed in Annex B. Design configurations include double-flanged models, as well as lug and wafer-style versions, ensuring full compatibility with ASME and MSS flange connections. Nomenclature and typical assembly diagrams are presented in Annex C of the standard.<\/p>\n","protected":false},"featured_media":0,"template":"","meta":[],"wiki_category":[111],"class_list":["post-69669","wiki","type-wiki","status-publish","hentry","wiki_category-api"],"_links":{"self":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki\/69669","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki\/69669\/revisions"}],"wp:attachment":[{"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/media?parent=69669"}],"wp:term":[{"taxonomy":"wiki_category","embeddable":true,"href":"https:\/\/evgroupchina.com\/en\/wp-json\/wp\/v2\/wiki_category?post=69669"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}