Welded Pipes in pressure vessel

[vpkhati]

Hi,

I have one query and doubt regarding welded pipes.

Can we use welded pipes instead of seamless pipes. The stockiest has given us the option of welded pipes because he is not having the pipe over 20” in seamless condition for the required Schedule ( The pipes are of SA 312 TP 316L & SA790 UNS S31803 materials).

What are the necessary documents will I require to verify the pipes ?

What are the stress values criteria for the Seamless and welded pipes ?

 

[stanweld]

You can use welded pipe listed in ASME II for Section VIII constructed vessels. The stress values are defined in Section II, Part D. The materials documentation are defined in Section VIII.

 

[Duwe6]

Don't forget the "E" joint efficiency factor of 0.85 for the welded seam when you calc the shell.

 

[vesselfab]

if lethal service or in a client specification....100% radiography of seam is required

 

[TJOrlowski]

E=.85 for both seamless or welded pipe when the spot requirements of UW-11(a)(5)(b) are not met.

Ref: UW-12(e), and UW-12(d), and Appendix L Fig. L-1.4-1 through L-1.4-4

-TJ Orlowski

 

[Vinch]

TJOrlowski,

What is the point in spot radiography of a seamless pipe?
UW-11(a)(5)(b) applies to category B and C joints that intersect a seamless section. Not to that seamless section itself.

I think as per ASME sect.II part D stress value tables, E=1 for seamless pipes and it depends on what the weld process is for welded pipes.

 

[SnTMan]

For some welded pipe a 0.85 factor is included in the allowables. See SecII, Part D, Table 1A, Note 3 for example.

Regards,

Mike

 

[unclesyd]

There is noway that I would construct a PV with welded pipe without 100% weld inspection either radiography and UT or UT with a little radiography. This is based on our problems with non-welded welded pipe in nearly every size and grade.

As pipe we had to replace 4 stalks of 20" schedule 80 SS pipe due to leaks at the weld seam. Fortunately for us it was leak before break as the working fluid was Cyclohexane Vapor. All this pipe was supposed to be 100% inspected at the factory. The defects were mainly lack of fusion and/or penetration.

 

[rmw]

unclesyd

Can you post a link to the thread where you once described that experience. Do I remember correctly that you had once mentioned that problem in detail in a thread?

It might be beneficial to the OP's thinking on the topic. I know it scared the bejesus out of me when I read it.

rmw

 

[unclesyd]

rmw,

You arethe luckiest person alive, so go bet on the lottery.

thread378-70822

thread378-247851

I recently heard that one the sister plants just found a bad seam in a piece of 12" Sch 40 #04L SS pipe. The leak was welded up with no investigation.