API 609 Category B Butterfly Valve

API 609 Category B Butterfly Valve is designed for demanding industrial applications that require precise pressure-temperature performance, reliable shut-off, and long service life. Manufactured in full compliance with API 609 standards, Category B butterfly valves are widely used in oil & gas, petrochemical, power generation, refining, and pipeline systems, where higher pressures and temperatures must be safely managed.

In all cases where the Official API Monogram is applied, it is used in conjunction with API Certificate Number 609-0341, verifying that the valve design, materials, manufacturing, and testing processes meet strict API requirements. API 609 Category B valves are pressure-temperature rated, meaning their performance is validated across specified operating ranges rather than based solely on cold working pressure.

Category B butterfly valves feature an offset seat design combined with either an eccentric or concentric disc configuration. This structural design minimizes seat wear, improves sealing performance, and allows for more reliable operation under elevated pressure and temperature conditions. In some applications, the seat pressure rating may be lower than the body rating, which is clearly defined in accordance with API 609 guidelines.

The API 609 Category B standard covers valve sizes from NPS 3 to NPS 24, with pressure classes including ASME Class 150, Class 300, and Class 600. These valves are available in wafer, lug, and flanged connection types, offering flexibility for various pipeline layouts and installation requirements. The standard also strictly defines face-to-face (FTF) dimensions, which are critical for ensuring interchangeability and proper installation in American-standard piping systems.

One of the key technical distinctions of API 609 Category B butterfly valves lies in their structural length specifications. Compared with national GB standard butterfly valves, API 609 flanged butterfly valves share similar structural lengths, while wafer-type valves—particularly in 6-inch and 8-inch sizes—show significant dimensional differences. For example, a 6-inch Class 150 API 609 Category B butterfly valve requires a face-to-face length of only 57 mm. Manufacturers using longer body lengths, such as 70 mm, are often adapting GB standard molds rather than producing true API 609 valves.

As a leading API 609 Butterfly Valve Category B manufacturer in China, we strictly adhere to genuine API dimensional standards, ensuring accurate face-to-face lengths, certified performance, and full compliance with API 609 requirements. Our valves are trusted worldwide for their precision engineering, durability, and suitability for critical American-standard pipeline systems.