Connecting API pipes with API 6A (Type 6BX) Flanges

[philteo]

Hi,

I am trying to connect a 6" SCHXXS, X65 pipe with an API 6A(Type 6BX) Weld Neck Flanges. Could anybody suggest what size of the flange I should be using as the dimension for the pipe and flange are of 2 different standards.

Cheers

 

[LittleInch]

This site might help you

http://www.woodcousa.com/flange/weldneck.htm

Basically the API 6A sizes have reduced bore to match standard ASME pipe sizes, therefore a API 6A 7 1/16" flange will actually mate to an ASME 6" (6.625" OD) pipe.

Traditionally the wellhead flanges mostly mated directly to other flanges without this pesky pipe in between.

As in all things, check the details of the inner bore, but usually you can get the flanges machined to match the pipe unless something is seriously being de-rated.



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[philteo]

Thanks LittleInch for your kind reply. Appreciate it very much. Now we are looking at the 5.1/8" API 6A (6BX), 10,000psi to see we can machine the flange to fit to the 6" SCHXXS API pipe.

Cheers

 

[LittleInch]

I would get a custom made transition piece with angles no greater than 1:4 If I was you in whatever material your pipe is. Machining the inner bore to get the same ID and adding weld material to make up the difference in OD might be OK, but the transition piece will look a lot nicer....

Just to be clearer, it would seem that above API 5000, the connecting pipe is not a standard ASME size pipe.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[philteo]

Tks for the kind advice. I cannot visualise how the transition piece would look like.(what is the angle of 1:4) Can you please kindly provide a sketch on this transition piece with the flange and pipe so that I can have an idea. The pipes we are using is API X65. Working pressure for this setup must be able to withstand up to 5,600 psi. Thanks again.

 

[LittleInch]

First, define the code you're designing your pipe to - makes a big difference - then we can see if you're correct.

See this

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

and scroll down to about half way (the 6th section drawing) The 1:4 referred to is the slope of the angle as shown on the drawing in the website attached.

I am kinda worried that you're asking these sorts of very basic questions about high pressure piping. Is there someone else in your company / location checking and signing off your designs??

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.