P44 PQR / WPS Qualification

[apiguy]

I have a question I would like to have cleared up.
Scenario:
A PQR qualified ASME SB-619 UNS N06022 to itself. The WPS reads P44 to P44 with no UNS number specified. The production material is ASME SB-619 UNS N10276. ASME IX section QW-420 provides instruction for P numbers of the same UNS grouping across the different ASME Spec. numbers but does not clarify having different UNS numbers as being the same P number.Intrepretation : IX-90-36 Question 2 appears to provde a partial answer in that a different UNS number was not allowed to be considered as the same P number to reduce PQRs. This material is being used for a lethal service and we need proper verification of the WPS.

 

[struggling]

Sounds like you need a welding engineer and a metallurgist. If it's being used for lethal service, I don't think either will give a meaningful answer in an e-mail.
I know that when we have special welding tasks which doesn't fit an established WPS, we have to prepare a special checklist to obtain prior approval from a certified welding engineer acting on behalf of the owner. Good luck.

 

[apiguy]

Thanks for the information....

 

[Seldom]

Well apiguy, did you run another PQR or did you go with what you had?

 

[apiguy]

After probing every avenue I could find, all of the people who have responded seem to think that as long as the materials have the same P-number then the WPS is valid.Upon my visual inspection I found that quite a few of the welds had incomplete penetration all the way around. I requested that the welders be re-certified according to the field conditions which are welding 2" sch 10 square groove welds instead of that big ol'6" sch 80 they used at the testing laboratory.

I submitted an inquiry the ASME committee for an interpretation today. Hopefully they will respond.

If anybody else has any information regarding this subject, please feel free to jump on in.

Now, I'm off to figure out why our SA-312 Type 254 SMO welds are cracking in the toe of the weld....Any suggestions?

 

[Seldom]

I agree with the use of the original WPS as you’ve mentioned others have as well.
I’ve used/seen one WPS where both of the materials you’ve noted were included in a “combination WPS” with only the obvious corresponding change of filler metal noted.

You’ve also mentioned a condition I’ve found that is quite common to welders with previously issued P4X qualifications. Many have serious problems with IP on production work. Enough of a problem where I’ve stopped jobs and required immediate retests of everybody. Interestingly, the welders with the most trouble with P4X welds are the “cup-walkers” and far less with the "free-handers". They seem to rely on more repetition then visual aids when running the root bead, so when the joint design/configuration changes, they can’t adjust easily! In addition, an sch 10 sq-groove is a long way from a v-groove with a knife-edge when welding P4X materials!

Good luck with the toe cracks.

 

[Seldom]

Sorry, I forgot to mention in my previous reply that you’ve probably found what I’ve always considered the weak spot with the ASME performance qualification allowances when using carbon steel coupons instead of P4X material to test with. In my experience, carbon steel doesn’t compare in weldability characteristics or exhibit mannerisms whatsoever conducive to the P4X’s!

 

[pipewelder1999]

I don't know exactly what you are asking but just because a p-number matches does not mean a WPS is "good" for all P-numbers. If I qualify a P-8 to P-8 PQR using 304 base metal with 308 filler metal and write a wps for 304 to 304 with 308 I don't have to do another PQR for 316 to 316 using 316. I do however have to prepare another WPS. If all other essential variables are the same, no additional PQR is needed.

More than likely all materials within the group can be joined with a filler metal for that group. That does not mean the joint will be fit for service.

I would look at the manufacturers recommendations for joining the material, If those recomendations are within the qualified ranges allowed bythe original PQR , then prepare a wps using the appropriate filler metals and parameters with support of the original P-44 pqr.

And of course get engineering review.

 

[apiguy]

Seldom,
Do you have any experience with nitrogen as a backing gas for high nickel weld deposits?

 

[Seldom]

Hi apiguy,
I don’t recall any experiences offhand where I’ve used nitrogen purge on P4X materials. I only remember using it when we needed a large volume for purging in the field. We used our plant nitrogen system and then only with P8 materials (304 & 316 SS) specifically.

Understanding that nitrogen is not an inert gas and is an alloying agent, we had to use tight root opening so as not to pickup any more nitrogen in the arc then necessary. This was done in order to minimize the chances of hot cracking due to loss of ferrite content. The use of the nitrogen purge in each case scenario was approved and supported by our in-house metallurgical group and I was unaware of any problems arising from its use while the weldments were in-service.

Sorry that I couldn’t be of more help apiguy but I’d suggest checking with the materials forum here for possibly a more specific answer and/or guidance to your question.

Always hate to have to start cutting out welds myself without touching the all bases first!!

Good luck

 

[apiguy]

thanks anyway...I've got the manfacturer's welding engineer on my side now so it will be tough to keep any welds in the field now. By the way, you have mentioned P4x materials a couple of times now. Are you referring to the Hastoloy or another material? Richard Schram
Mechanical Integrity Specialist
Pharmacia Global Supply Arecibo-P. Rico
rschram@pharmacia.com