API 650 storage TANK - Socket Welds between Flange- pipe

[Alessandro87]

Dear All,

My question is pretty simple; on Storage Tank according to APi 650 for small pipes (minus than 2") are Socket welds between Flange and pipe allowable ?

As per what I can read on standard,this kind of junction is not considered.

I kindly ask your support!

Regards

 

[JStephen]

Socket-weld couplings are permitted, so the socket-weld idea seems not to be forbidden. See the last sentence in 5.7.6.1.b, which I assume allows grooved ends, welded connections, etc.

 

[Duwe6]

If anybody asks, you built the small-bore piping i.a.w. ASME B31.3 and used approved socketweld fittings. API-650 & 653 are pretty silent on small-bore piping.

 

[JStephen]

Also, let me clarify, I'm assuming you mean a nozzle flange. If it's beyond the first flange face, it generally wouldn't be covered by API-650.

 

[Alessandro87]

Dear All,

thanks for your replies.

As I can see from code, Socket welds connection is clearly stated for nozzle to shell connection ( see Fig 5-8 c ) but not to flange-pipe connection (see fig 4.3 and par 4.6) where all other kind of flanges are showen.

My question was just to understand reasons why API 650 doesn't refer to this kind of connection. In my opinion a reason could be that the lack of the internal welding (where the pipe will be in touch with the flange) could lead to creavice corrosion when corrosive fluid are carried.

It's just my opinion. What do you think about that ?

Thank you !