GTAW Weld Pass "washing" of C/S Pipe Welds 5

[Zylinderkopf]

Greetings to all:
During recent installation of AMSE B31.3 pump suction and discharge piping systems at our refinery, I came across somoe of the pipe butt welds that presented an appearance such that they have possibly been "washed". The subject butt weld joints are located between pipe sections and pipe-to-flange (RFWN design).

The subject piping material is ASTM A106 Grade B Carbon Steel, NPS 6-inch schedule 80, The flanges are ASTM A105 Carbon Steel.

The welded connections were initially made in the "shop" and the spools were installed in the field. The subject piping was earlier found to have a small amount of mis-alignment once it was in the process of being installed to the pumps' (centrifugal type with suction) suction (axially orientated) and discharge (vertically orientated) nozzles.

To be sure, there are many issues that surround this particular matter. However, for this "post" only, I had returned to the refinery Unit where the subject work was being carried out. The OD surfaces of some of the piping presented such that it appears to be (at least to me) noticeably misaligned in way of the pumps suction and discharge nozzles.

The butt weld joints in this area presented weld crowns with a remarkably clean and smooth surface contour. The painted coating in this location (white-colouored pigment) was removed, with the areas of removal presenting a feathered and scorched appearance.

As such, it appeared to me that these welds had been "washed" (perhaps with GTAW equipment?) and the pipe joints "massaged" such that the piping could become installed. Conversely, I may simply be paranoid...

These welded connections have subsequently passed the "third party" NDE VT and PT inspections (I had read before "somewhere" that washed welds of this nature would most likely "pass" PT).

My questions are:

(1) Is it possible that weld pass washing technique(s) can be utilized to manipulate piping butt joints such as to solve minor alignment challenges?

If the answer is yes, then:

(2) Is there such a thing as a Weld Wash Procedure that can become qualified (probably not?...I suppose it is more of a welding "technique" than anything else?) - would any of you know how I could locate such a Procedure?

(3) Is weld washing addressed (most-specifically, prohibited) by any of our "popular" AWS and/or ASME Codes?

(4) If my case is one where weld washing has been utilized in the subject instance, am I justified requesting that the joints receive an NDE RT? The intent here would be to quantitatively determine the degree of misalignment at the butted pipe walls(?)

Thank you for your time and kind consideration of my enquiry.

 

[unclesyd]

normally one the reason for washing a weld if it is ugly.
Yes; you can use TIG torch for local heating of pipe, though this would be rare in your case due to the sizes involved. If the weld has been disturbed you have the option to reexamine it by whatever method that is appropriate.
Some questions.

What was the welding procedure for the original weld? Something like TIG root finish out with SMAW.

Does it look like he added filler to weld bead?
Sometime things like bad undercut will be filled in with TIG, even though this practice is frowned on.

Are there any file marks on or around the weld bead?

If the weld capped the weld out with TIG and used a technique called walking the cup it might appear that the weld metal has been washed.




FYI:
Originally when TIG , HeliArc, was first used on SS it was normally part of the procedure to wash the caps. We called the welders who did this "Weld Doctors"."
During this peroid TIG wasn't allowed on CS pipe as it was all gas or stick welded. It seems strange today that our most critical piping, 10,000 psig H2, was gas welded.

 

[Zylinderkopf]

Greetings, unclesyd:

Thank you for taking the time to respond to my enquiry.

Please accpet my following responses to your questions, vis:

Q: What was the welding procedure for the original weld?
A: The refinery Quality department permitted the attending Contractor to use a WPS that is, reportedly, analagous to the WPS that the refinery has a WPQR for. The refinery WPS would allow TIG root followed by filling using SMAW with an E7018 electrode. I would like to tell you with complete certainty that this is the case in this instance, but, I am regretfully not 100% confident that the Contractor even follows their own WPS's. (rather a harsh statement, I know...my prejudice is based upon "previous experiences")

(2) Q: Does it look like he added filler to weld bead?
A: The weld presentation does not appear as if any filler metal was added to the weld bead...there is a convex crown geometry that uniformly extends approximately 25% of the pipe butt joint OD.

(3) Q: Are there any file marks on or around the weld bead?
A: Unclesyd, I "think" that I udnerstand this question, which is clear and only owing to my own ignorance lies my confusion. Since receiving your question, I re-visited the installation hoping to obtain a photo to post (hindsight being what it is for me...). However, I found that the pump steam turbine driver is having its casing steam-purged and the pump location was completely obscured from sight. My apologies. During my earlier visit, the weld crown presented as having a very high, almost reflective, luster and appeared to have faint, semi-circular marks contained in it. There were no raised edges to these marks such that I could get a fingernail to "catch" on any of them.

By the way, I've benefitted from the multitude of responses that you have posted to other questions at this Forum. I'm flattered that you have taken an interest in mine.

 

[unclesyd]

Based on your response it appears that the weld has done some cosmetic repair to this particular weld. Since I used the word file I should have considered file or grinder as the tool used. On welds that don't require post weld heat treatment a little cosmetic repair if OK, but the welder should check to see if this permissible. The weld bead should be uniform over the entire circumference not the amount mentioned in your post.
I definitely would keep track of this welder or any welder that requires cosmetic repair to their weld bead. Again it not uncommon for welder to dress the edges of a weld bead if there is a rough edge or trapped slag. This shouldn't be a chronic problem when using 7018 electrodes assuming that he keeps his electrodes from absorbing moisture.

Your mention experience with contractors performance, I know exactly what you mean as I'Ve fought that battle many times. Until recently we have had a every welder's performance record while doing any welding on our site.

 

[qcrobert]

(1) Is it possible that weld pass washing technique(s) can be utilized to manipulate piping butt joints such as to solve minor alignment challenges?If the answer is yes, then2) Is there such a thing as a Weld Wash Procedure that can become qualified (probably not?...I suppose it is more of a welding "technique" than anything else?) - would any of you know how I could locate such a Procedure?(3) Is weld washing addressed (most-specifically, prohibited) by any of our "popular" AWS and/or ASME Codes?(4) If my case is one where weld washing has been utilized in the subject instance, am I justified requesting that the joints receive an NDE RT? The intent here would be to quantitatively determine the degree of misalignment at the butted pipe walls(?)

A washing technique with GTAW process is usually performed to make the weld cap cosmetically appealing.

The low heat wash of GTAW will not reallign the ID allignment, however it may make the OD cap look better alligned.

The wash technique may have been utilized with a water quench to relieve the stress of misallignment between the pump and piping attachment. If so, the contractor should have a written procedure showing how this was accomplished especially how much heat (degrees F) was applied to the weld joint or pipe being realligned.

 

[stanweld]

We had a weld fail where the welder GTAW washed a SMAW, F43 weld deposit. Only the wash pass fused with the base metal -less than 1/16" thick in a 5/8" thick weld. Needless to say the weld failed during warranty yet passed hydrotest. Our inspector obviously missed visual examination, noting that there was no qualified procedure using the GTAW process for the dissimilar metals weld involved.

 

[Zylinderkopf]

Greetings, and many thanks for all of you who took the time from your busy schedules to respond to my post.

Great information from everyone...thanks again!

 

[Mr168]

I think it's important to take a step back and approach the basics first. I'd postpone the "what NDE can I do to cover the contractor's work" thought process, and begin with a "what can I do to make the contractor justify its actions and/or rectify the situation."

First and foremost, you need to determine whether the contractor is meeting its responsibility:

1) Did the contractor provide a valid PQR, or was the PQR "borrowed" from the plant? The latter is prohibited under ASME code.

2) Give them the benefit of the doubt (tongue in cheek) that they didn't cheat by washing the cap, but rather that they used GTAW with filler for that portion of the joint. Does their PQR support a deposit and wall thickness with GTAW for the joint in question? If not, there are grounds for making them excavate the joint or have the joint subject to additional NDE as they did not use a qualified procedure.

3) Has anyone talked to the contractor's welder directly and asked what he did? Perhaps they repaired a portion of the cap with GTAW using the walk the cup method. If the area was hit with a wire wheel afterwards, it can be more difficult to distinguish a weld with filler added vs. a dry wash.

4) Has anyone asked them how the misalignment was rectified? It's possible to make the pipe draw one way or another by using localized heat, but in my experience, on pipe that small, they're more apt to yank it into place with a come-along or chain-fall and tack it.

 

[qcrobert]

<<<We had a weld fail where the welder GTAW washed a SMAW, F43 weld deposit>>>

We wouldn't have allowed a wash over a nickel alloy matl., only on P1 matls like the A106 that Zylinderkopf was speaking of.

 

[Guest102023]

This is tricky territory, IMO the bigger problem is that of the welder playing impromptu welding engineer and taking liberties with procedures and practices. One particular issue is that they do it without preheat or even after final PWHT.

Technically washing is OK, but it needs to be included in the procedure qualification process, since at least one essential variable is different (no addition of filler metal). If I were plant welding engineer I would want to review every case personally before giving the OK.

Give then an inch and they ...

 

[Zylinderkopf]

Greetings and thanks-all-around.

Mr168, thank you for the education. Please accept my following responses to your questions, vis:

(1) The Contractor provided the refinery Quality department with a plethora of WPS's for the applicable weld joint types that they had anticipated as being required during their attendance (during a fast-paced turnaround...well, I suppose that's redundant as they are all "fast-paced"). During this time, I have not yet found any of their approved WPS's that include a stipulation for a weld "wash".

(2)The attending Contractor has now departed from the refinery. I am inclined to sympathize with them as they are instructed (as the refinery staff has been) to do with what our Managers (this does not mean Leaders) demand in terms of "doing more (work) with less (resources, personnel)" (sic). The Management is not inclined to excavate the welds that I have questioned as it has been determined that it is not such a significant issue as to warrant any obstacles with teh refinery start-up date promised to the Corporate officers.

(3) & (4) I did not speak with the attending Contractor about the weld joints that I question, and, per Item (1) above, I have missed the window of opporutnity to do so, or, at least as I have been instructed.

Until now, I did not know what crow tasted like...

Mr. Brimstoner, your comments are well noted. Thank you!

 

[stanweld]

qcrobert,
GTAW washing wasn't permitted; in fact, it is prohibited for Nickel base filler metals. Sometimes welders may do things to mask their poor welds. Weld supervision and QC is supposed to catch the culprits but sometimes they don't. Unfortunately, the culprits were long gone before the failure.