API 6A or ASME Sec8 Div2 2

[bryansonnier]

Our company manufactures valves for the oil and gas industry. Our valves usually don't fall into the normal api valve listings as these are throttle valves 5 ksi range using dual orifice discs to control flow (think willis or baker forum or taylor throttle valve). We are gearing up for ISO certification and are formalizing our design process for future products. I would like to put a design procedure together to make sure we don't miss anything and to cross our T's and dot our I's. Is there an API design spec (is it 6A) that would be a solid basis or does AMSE Sec. 8 Div 2 work better?

Is there another design spec that would work better than those for this purpose. Currently our customers don't require one spec or the other. We are just getting into the international market and for the most part they just require a spec and aren't picky as to which one be it ISO/API/ASME etc...

Any help would be much appreciated, thank you.

(i will also post this in the asme forum as well)

 

[LittleInch]

bryan,

You've been around here long enough to know you shouldn't double post.... and this might be better in the valve forum.

For me this sounds like an API6A valve if you're in the 5000psi range. ASME VIII is really a PV spec and doesn't usually work that well for flanges and valves.

Kind of depends what it is normally used for - these sound like wellhead choke valves, but if not then another spec might be more appropriate.

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

 

[bryansonnier]

I know double posting is frowned upon, but i'm trying to get the asme guys opinion as well as the api guys opinion. Hoping to get a consensus in the middle somewhere i guess.

If these were on the christmas tree i would definitely go with API as that is the spec usually called out for that application, however, our valves are (at least currently) specifically not on the wellhead. Usually they are at most just downstream of the wellhead if not on some other process throughout the industry (upstream and down).

The benefit of ASME VIII is it has a really fleshed out design by analysis system with tables galore of allowable stresses etc... The downside (like you noted) is that is originally for pressure vessels.

 

[LittleInch]

Have you looked at API 6D?

Or even ASME B 16.34 - it's just that 50000 psi rating which stops the ASME codes form being the ones to use IMHO.

Or just say its a "special" and conforms to the general principles of ASME VIII....

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

 

[jmec87]

Can you get your valve to pass the ASME VIII calculations using the applicable allowable stresses? Are your valve materials listed in the ASME VIII allowable stress tables?

If the valves are just downstream of the wellhead, then API 6A (or at least the applicable/relevant) parts of it are probably your best bet. Some manufacturers claim that their valves and other products meet API 6A despite them being out of scope - I would either avoid any claims of API 6A conformity or carefully word them so they are accurate.

API 6A references API 6X, which is based on ASME BPVC Sec VIII Div 2:2004 w/ 2005 + 2006 addenda, but API 6A has higher allowable stresses than ASME VIII and has flexibility for you to essentially do whatever you want to justify your design.

 

[bryansonnier]

I had been using ASME VIII div 2 design by analysis. Thanks to a reply on one of my other posts I was reminded about the elastic perfectly plastic Limit-Load method Section 5.2.3. The valve analysis converged at 2x working pressure which is adequate for our applications.

Thank you all for the help