Air Cooler: plug box with welded joint

[Peregrino7]

I have an air cooler for Hydrogen service with high pressure. It is specified that header be plug-box type, which is ok. But it is also specified that tube to tubesheet joint shall be strength welded.
Is this mechanically possible? If API 661 establish that PWHT shall be performed before tubing. Is it possible to make strength weld through the holes of the plug ??
Is there another way ???
Header with removal cover is not allowed because of the Hydrogen service…
I also wonder if the strength welding of the tube to tube sheet joint is really necessary.

Thanks for your help.


GH

 

[speco]

Peregrino7,

Yes, it's possible to weld the tube-to-tubesheet joint through the plug holes. I believe it's done all the time.

Some customers even require that the headers be stress relieved after the tube are welded in. That can also be done, but it's a real pain to do, and quite expensive.

Regareds,

Speco (

http://www.stoneprocess.com)

 

[gr2vessels]

As speco said, it is not uncommon the welding through the plug holes. However, for consistency and appropriate quality you should insist on an automatic weldig procedure, with full mock-up test. Some of the manufacturers would propose manual welding, but the testing is not always conclusive and human errors...(Also, max. 248 HV10 !)
gr2vessels