Tube-to-tubesheet welds - ASME IX - PQR

[YMech]

Hi Everyone,

We are welding stainless steel tube-to-tubesheets joints for one of our customers. We currently have a WPS/PQR to perform GTAW on stainless steel, which works for our application. However, our welder is finding that it is easier to not use any filler metal in welding these joints, so we are needing to create a new WPS/PQR.

Are tube-to-tubesheet welds considered a pressure retaining weld? I am trying to get away from doing the ASME IX tube-to-tubesheet procedure (I'm referencing QW-202.6), as we do not have time to purchase 2" thick stainless plate (the tubesheets we are dealing with are greater than 2" thick). I would like to perform a mock fillet weld test and qualify our welder from there, so what is to say I can't do that instead of the tube-to-tubesheet procedure?

Any input? Thanks in advance!

 

[YMech]

Also, I would like to add - we only received the tubesheets with the tubes, not the shell encasing. Does anyone have experience with this? We are not repairing any welds, as there were none to begin with, so not sure about the testing requirements as far as pressure testing or NDT, and if this requires NB stamping/certification.

 

[SnTMan]

Are tube-to-tubesheet welds considered a pressure retaining weld?

To realy answer that it would be helpful if Code if costruction was known. For example under Sec VIII, Div 1 there are two approaches to tube-tubesheet welds, namely UW-20 and Nonmandatory Appendix A. Knowledge of design requirements of the joint may be needed as well.

Best consult with your customer...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[pradipgoswami]

Tube to Tube sheet welds are "Pressure Retaining welds". Conventional Sec-IX qualified groove welding procedure for qualifying a T#TS weld, is not acceptable. For quite sometime Sec-IX had incorporated the PQR/Mock Up qualification requirements, ref-QW-193 guidance.

Are you're trying to switch from a technique with Filler to a Technique with No Filler?
Then I would say a Mock-Up is mandatory for qualifying everything, Procedure/Mock-Up, welders. I would think QW-193 is very clear about such qualifications.


Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[EdStainless]

Were you told to do 'seal welds' (no filler) or 'strength welds' (with filler)?
Two very different cases.
Seal welds are not structural, strength welds are.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[SnTMan]

Then there is the nomenclature "seal weld w/ filler metal", just to cloud things up a bit

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[metengr]

SnTMan has it right. Also, you must evaluate the design regarding tube to tubsheet weld joints. Seal weld with tube rolling and partial penetration groove welds joining tubes to tubesheets are different designs and must be dealt with accordingly.