screwed flang in the API 1

[kugelhahn]

Does anyone know, if the API has a part about screwed flanges? We would like to desing a screwed flange 16" ansi 2500. If there is a part in the api desrcibing such flanges, please let me know where to find? Which chapter?
The german AD2000 has a part about, see attached picture.

 

[11echo]

You are trying to have a 16" threaded connection in 2500# service!!? ...Good Luck with that!

 

[ricklts]

not a good idea. what threads would/could be rated to ANSI 2500 service?

What service do you intend to use this connection for?

Many alternatives, even excluding welded.

 

[kugelhahn]

So now i found ANSI B16.5 about threaded flanges

Why should threaded flanges should not be a good idea? It is not the problem to design such threaded connection. I calculated a double testing pressure and a high temperature. i get a force round about 1700 tons. Its a M674 with a lengh of 90mm. I see no problem?
We will try it now first with a 1500 claas and water testing.

 

[JStephen]

If I'm reading the abstract right, the 2500# flanges in B16.5 only go up to 12" size. I don't have the full standard to see.

16" threaded flanges are routinely used in the waterworks industry to fabricate flanged spools using ductile iron pipe. But this is in the 150# flanges, not 2500#.

I think the point about "what threads" up there is that 16" standard pipe threads may not be adequate for the pressure. If you're doing custom pipe threads and all anyway, that may not be an issue. It still seems like an odd solution, though.

 

[ricklts]

kugelhahn,

JStephen is correct, there is no 16" 2500# ANSI flange design, stops at 12". I looked at your attachment, and it looks like you want to substitute a threaded collar arrangement for the flange, using an internal sealing mechanism in lieu of the RF or RTJ seal.

This could qualify under several of the 'Other End Connector' portions of API, but that would require additional qualifications, FEA, etc.

What code/design conditions are you designing to? What materials for Female threaded Hub and pipe?

 

[11echo]

I work in the oil fields; we deal with 2500# systems for time to time (mostly steam & waste injection). Now normally the sizes we deal with are between 3" to 8", BUT we don't use threaded connection (for piping) on any system above 600# ...and even at that rating threaded connections are normally just instrumentation. Leak potential is just too dangerous for operating personnel!

 

[zdas04]

ANSI 2500 flanges in Carbon Steel Material Group 1.1 less than 38C are rated to 425.5 bar (6170 psig). I can do threads at that pressure, but they ain't NPT.

I've seen ANSI 900 Huber Closures on pig launchers bigger than 16", but those closures have massive square threads and o-ring seals. There is no reason you couldn't do the same kind of threads and secondary seals at ANSI 2500.

David