Butterfly Valve API 609 Category B

What does the American Standard Butterfly Valve API 609 Category B mean?

API 609 is the design standard for the American standard butterfly valve, which specifies the structure length is divided into Category A and B, in Chinese is the structure length of API 609 A butterfly valve and B butterfly valve, also called the body length. Also different in design/Inspection. Here we focus on Face to face of API609 Valve.

Butterfly valves are categorized according to their structure. Nowadays, there are more midline/center line butterfly valves and eccentric butterfly valves on the market. The standard length of the American standard butterfly valve used in the center line butterfly valve is the API 609 Class A butterfly valve. The eccentric butterfly valve is mainly a three-offset butterfly valve. The structure length standard adopted is the Class B butterfly valve regulated by API 609.
The Class B butterfly valve of the API 609 standard specifies the structure length of the American standard butterfly valve, flange butterfly valve and lug butterfly valve. In comparison with the national standard GB butterfly valve, the flange butterfly valve and the national standard butterfly valve structure length is same, but there is a gap between the clip butterfly valve, especially the 6 inch, 8 inch difference between the two specifications/standard  is largest. This is also an way to judge a manufacturer is they are professional  in produce American standard  butterfly valve.
In the API 609 Category B, the 6-inch to 150LB butterfly valve is specified, the structure length is only 57mm, and many manufacturers, or 70mm, is the same with the national standard valve body, it can be seen that many American standard butterfly valve manufacturers directly to use the national standard valve mold. The valve body was modified to the American standard connection size.
Our American standard butterfly valve has a unique set of molds, which are designed and manufactured according to API 609 and other related regulations. Therefore, regardless of the valve body thickness, flange thickness, and structural length can reach the relevant standards.


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