Valve International Standards

What is API 609? Complete Guide to the Butterfly Valve Standard

2026-07-06

API 609 is the American Petroleum Institute standard that governs the design, manufacturing, testing, and marking of butterfly valves used in the petroleum, petrochemical, natural gas, and industrial process industries. First published in the 1980s and regularly updated (most recently in 2022), API 609 is one of the most widely referenced butterfly valve standards worldwide alongside AWWA C504 and EN 593.

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AWWA C504 Butterfly Valve: Complete Guide to Standards, Pressure Classes & Selection

2026-06-25

If you are involved in specifying valves for municipal water systems, wastewater treatment plants, or industrial waterworks, you have likely encountered the AWWA C504 standard. But what exactly does it cover, and how do you choose the right valve for your application? This comprehensive guide explains everything you need to know about AWWA C504 butterfly valves — from pressure classes and flange configurations to seat designs and face-to-face dimensions.

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