API 6BX flange hubs matching ASME B36.10 nominal pipe sizes

[svi]

There is a trend to use the API 6A flange standard on piping system designs for flange ratings in excess of ASME class 2500, despite the fact that the API standard is intended for well head applications. The nominal sizes between these standards do not match. Transistion pieces to match the dimensions may be a resolution, with consideration for the material strengths of the hub and the matching transistion piece and the continuing pipe. What are the recourses to this problem?

 

[jbeckhou]

API does give dims for neck diameters but you can use other "dims" to match your design. Dim "B" (api-6a) could taper well below the Nom size of the flange. As long as the "flange" dims are per API, the back side of the flange can be designed to meet your needs.



Petrotrim Services

http://www.petrotrim.com

 

[svi]

I understand that there are restrictions though, to having a hub to match the B36.10 nominal pipe sizes. The hub taper may not be ASME code (ASME B31.3 to which the piping system is designed to) complaint. This is addressed at,

http://www.woodcousa.com/about_wnf.htm

 

[blacksmith37]

This conundrum has provided engineers job security for 50 yr. I recall one solution was a spool piece; API on one end and ASME/ANSI on the other end.