Preliminary welding procedure specification 1

[Mohamed Elshamy]

Dear all I hope you all fine
A little question ( could I weld thredolet or socket 3/4 inch with SMAW) for pwps
Thank you

 

[metengr]

Can you please come back with more information? I prefer socket welds on 2" or less diameter fittings.

 

[Mohamed Elshamy]

Pwps. Is a shortcut for preliminary welding procedure specification and the case i want to weld socket 3/4" as a drain into pipe 6" with SMAW process and if there any WPS supporting this issue please send it.
Thank you so much for responding

 

[metengr]

You need to qualify your own WPS using either ASME B&PV Code Section IX or other international welding specification. This is how you learn the business.

 

[gtaw]

The PWPS is the engineer's best guess of what will work. The PWPS is validated by welding a sample using the PWPS as the "guide". If the test assembly passes, one has qualified the PWPS. It can be rewritten as a qualified WPS for production welds and is supported by the PQR.

Best regards - Al

 

[metengr]

GTAW;
Sounds like more work than necessary and really a duplication of effort. You write a WPS and qualify it using a PQR.

 

[DekDee]

metengr,
You have the egg before the chicken.
You need the variables from the PQR to write the WPS.
As Al stated it is the engineers best guess to give to the welder to follow when welding the PQR coupon.
Predominantly used in ISO codes/standards.
It could be called a duplication of effort but it does have some beneficial uses.
As an example, we regularly get PWPS submitted by contractor to client (when working with ISO)for approval.
Waste of time and money qualifying a PQR if the client will not accept the final WPS (eg. may be code compliant but not project specification compliant)
Cheers,
Shane

 

[gtaw]

The preliminary WPS provides direction to the welder on what is needed; the details of the joint to be welded, the filler metal to be used, welding parameters, etc. It also tells the welder what preheat is required, whether post weld heat treatment is required, and any heat input limitations if and when notch toughness testing is needed.

The alternative is to throw a couple of plates on the bench and tell the welder, "Weld these." And hope for the best.

The code doesn't say the welding of the PQR needs to be witnessed, nor does ASME require nonessential variables be recorded. In my book it is a missed opportunity if the data isn't recorded. It explains why I get several phone calls every year asking, "I just qualified the WPS, but where do I get the values for the voltage, amperage, travel speed, for the WPS?"

Many years ago I did an audit on a large manufacturer that included reviewing their WPSs. I asked the engineer, "Who recorded these parameters on the PQR?"

"Our welder records that information while he welds the coupons." was the response.

"He must be a pretty good welder. Is there a chance I can meet him?" I asked.

"No problem, he's down on the production floor." says the engineer.

"Great, let's go say hello." I said with a smile.

Introductions all around, and I asked the welder, "Do you remember welding up the plates for this PQR?"

"Hell yea, that aluminum is a pain in the backside." Responds the welder.

"Did you record the voltage, amperage, and travel speed?" I asked.

"You don't know Jack about welding do you!" said the welder.

"What makes you say that? I said.

"If you knew anything about welding you would know darn well I can't watch the weld pool and the meters on the machine at the same time!" says the welder.

"Good point. Where could these values have come from if not from you and there was no one to witness you welding the plates?" I asked.

Now we have a PQR with falsified data. Scratch one PQR and one WPS. While we're at it, best check the other WPSs and supporting PQRs. Scratch one welding program, all their PQRs, all their WPSs and start over.



Best regards - Al

 

[Mohamed Elshamy]

Thank you all for your kind responding,and I have another question: if i'd an old accepted PQR supporting wps for the same company dated feom year 2007 and the company responsible for all the work from designe to construction is this Pqr accepted now to a third party
Thank you so much

 

[gtaw]

If the PQR is correct in all respects, it can be used to support a new WPS. However, one must consider the construction code to verify any additional requirements are met. For instance, is post weld heat treatment required by the construction code? Is notch toughness required based on material, lowest anticipated temperature, are there joint restrictions, is backing permitted, are socket type fittings permitted, etc. A new PQR may be required if an essential variable is involved or the WPS may simply be revised to address limitations of the nonessential variables addressed by the construction code.

I reject many more WPSs than I accept because the contractor simply meets Section IX without considering the construction code, PWHT, notch toughness, etc.

Just because the PQR and WPS was acceptable for a previous project, it doesn't mean it is acceptable for a new project that utilizes a different P number/group number, thickness, construction code, etc.

Best regards - Al

 

[Mohamed Elshamy]

Thank you so much ( gtaw) you was very helpful and the PQR is conform to the construction code
So in this case i'll accept the WPS and will proceed.
Thank you so much

 

[DekDee]

Just a comment on your first post (we got carried away with the pwps).
Be very careful with trying to weld 3/4" with SMAW.
The thredolet/sockolet weld to run pipe must be a fully penetrated groove weld and you would need a highly skilled welder to do that without making a mess.
Much better option would be GTAW.
Cheers,
Shane

 

[gtaw]

Agreed.

Best regards - Al

 

[Mohamed Elshamy]

با ك الله فيكم.وهدانا واياكم الي سواء السبيل
This is in arabic mean Allah bless you and guide you and me to his way
Thank you so much for your support.