Does ASME B31.3 allow subsitution of API flanges? 2

[Jfarid]

Hi All,

We are designing piping for a wellhead whose shut-in pressure (6530 psi) is beyond the rating of ASME 2500 flange. I am thinking to use API 10,000 flanges and ASME pipe/fitings to design this system. Does ASME allows subsitution of API flanges? if it does, please advise me the respective section of B31.3.

Thanks

JFarid

 

[racookpe1978]

I'm going to defer to BigInch - and other petro specialist! since I'm more power-experienced - but it would appear to me that the "regulatory" ASME/API-type rules specify minimum requirements for "previously-agreed-upon cases" within specific limits of temperature, pressure, fluid type, flamability, etc.

If you recognize that you are designing outside the "written rules" then you MUST replace a too-small/too-weak fitting or pipe or flange comobination with one strong enough to fit the circumstances.

That is, you are an engineer, not a lawyer, and regardless of what the written rules say or do not say (if you require something that is not explicitly "allowed" in the rules because your pressures are higher than the rules go), you are responsible for specifying a pipe and flange combination that are strong enough to hold the fluids safely.

Specify it. Check it. Get somebody else to check it. Build it.

 

[C2it]

I have seen API flanges in B31.3 designed piping on many occasions. No problem.

There is an additional code .. API6AF2 if I remember correctly, that specifies limits for external loads on all API flanges.

 

[vpl]

B31.3 allows use of API materials. There isn't enough information in your post to give you a specific section number.

Patricia Lougheed

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[doses]

If piping design is under ASME B31.3 and pressure is over class 2500 (ASME B16.5) may be you should use "High Pressure Piping" (Chapter IX) rules.

 

[JohnBreen]

What do you mean by "substitute"? If the design calls for B16.5 flanges then that is what you must use.

API flanges are "unlisted components". They are not listed in ASME B31.3, Table 326.1.

If you are designing a piping system with flanged connections you must look to ASME B31.3 paragraph 303. Since API flanges are not listed in Table 326.1 (unlisted components), you must go to the rules of paragraph 304, specifically to paragraph 304.5. which of course take you to the ASME B&PV Code for design rules. If the "substituted" flange cannot be qualified by those rules you go to paragraph 304.7.2 which provides three ways of qualifying the unlisted component one of which is finite element analysis.

Regards, John