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Up Topic Welding Industry / Technical Discussions / Deletion of weld process
- - By Kraj Date 09-19-2007 05:17
Hi,

ASME Sec IX allows combination of PQR's to generate a WPS. A separate GTAW and SMAW PQR's can be combined to generate a GTAW+SMAW combination WPS within the code allowable limits.

Now, one of our contractor is having a qualified PQR for piping welding with GTAW + SMAW combination. Now he got a job of welding 72" piping and would like to use only SMAW process and will do the back gouging + SMAW welding from inside since easy access is available. All other parameters are meeting the section IX requirements. As per QW 402.4, Deletion of the backing in single side welded grooves are not acceptable. Where as Double side welded joints are considered as welding with backing. He is quoting this point and claims that existing PQR is OK. Logically & technically looks like correct. I could not find any thing in section IX. I would like to have AWS Forum members opinion.

Regards,
Parent - - By js55 (*****) Date 09-19-2007 14:08
In my opinion, and if my understanding is correct, what your contractor is wishing to do is acceptable procedurally. 402.4, even though not applicable here, as I understand it, is still only a non-essential variable.
The problem as I see it may be performance related. If the welders have not been qualified for welding without backing (for examp[led qualed by welding SMAW over GTAW) you will need a closed butt groove on the first side, which I'd probably do anyway to save groove volume. Why gap it at all if your backgouging?
Also, to say "deletion of backing in single side welded grooves are not acceptable", is not the best way to put it. As stated the deletion of backing (QW 402.4) is a non essential variable and therefore does not require requal. But your WPS does have to address it properly.
Your WPS also has to address backgouging and groove design issues as well, both non essential variables.
Parent - - By jon20013 (*****) Date 09-19-2007 15:06
js55, as usual a brilliant analysis however I'm unsure whether I agree with the comment towards performance; if the root is completely removed (i.e., the internal) then is there still a performance concern?
Parent - - By js55 (*****) Date 09-19-2007 15:30
Good catch jon. And in answer to your question, I don't know. I do not remember anything in IX that specifically addresses this point though it may be there. Its been awhile, and I just received the latest version. I do however remember something of an Interpretaiton to the effect. I just don't remember the conclusion. In light of my ignorance I chose to be conservative.
If your point is that you think it is acceptable without performance concern then I will defer to your opinion.
Parent - - By jon20013 (*****) Date 09-19-2007 18:43
lol, you are soooo damned humble for being such a talented Engineer!!!  My opinion is the performance qualification wouldn't be impacted in the case mentioned.  My ANI agrees.
Parent - By js55 (*****) Date 09-20-2007 13:42
jon,
Humble? Not sure I've ever been accused of that before. Hah!! 
I just plain don't remember. But it does bring up an interesting, to me at least, perspective for discussion sake if nothing else.
I defer to you and your ANI on its acceptability in code compliance (in other words-works for me), and I would suspect that this is reflective of the committees wisdom here. Wisdom attributed with recognition of my past criticism of committees. Not the individuals to be sure, just the often messy consensus results.
Technically how can you be sure you have removed the root pass through backgouge? Can you visually recognize the unreheated zone of the hotpass as you're scarfin down through it (clearly an absurd point to make a point)?
Code wise the committee has essentially said, in my opinion, and in light of your confirmation, this concern is unduly picky. And actually I would agree now. If you backgouge to clean metal does it really matter?
As I've emphasized in other threads, where are the failures to justify this picky of a concern? Perhaps this post sounds like a lot of blah, blah, blah, but discussions like this do take place every day.
Parent - - By MBSims (****) Date 09-19-2007 22:37
It is addressed in QW-200.4(a):

When following a WPS that has more than one welding
process, filler metal, or set of variables, each process,
filler metal, or set of variables may be used individually
or in different combinations, provided
(1) the essential, nonessential, and required supplementary
essential variables associated with the process,
filler metal, or set of variables are applied
(2) the base metal and deposited weld metal thickness
limits of QW-451 for each process, filler metal, or
set of variables are applied.
Parent - - By js55 (*****) Date 09-20-2007 13:43
Marty,
I not clear on how QW-200.4 addresses the performance backing issue.
Parent - - By jon20013 (*****) Date 09-20-2007 15:17
I believe Marty was responding to the original posting (first line item) which asked whether or not procedures would be impacted to which js55 mentioned performance as a segway comment.  Marty's point is right on the money, in my opinion, with regard to procedures.
Parent - - By js55 (*****) Date 09-20-2007 15:33
Thanks jon. Clearly I saw only the tree. You and Marty saw the forest as well.
Parent - - By jon20013 (*****) Date 09-20-2007 16:32
There ya go with that "humble" thing again, js55!!! 

Let me say this just once, so everyone in the Forum can read it very clearly... there are NONE among us, not a single one, who see's or know's all things about our field at all times!!! 

You, js55, seem to have a pretty good grip on quite a few of the "true" Engineering aspects of our field, in certain areas...

That said, most of us have special areas of interest where we may be a little more knowledgable than the next guy (or girl) but repeating, there is no one on this planet who knows everything there is about our field.  Nuff said.
Parent - By aevald (*****) Date 09-20-2007 16:43
Hello Jon, that was very well put and a true statement. In any trade there is no such thing as a true "know it all". As I learn, I also forget and need to be reminded, I do believe some of us are certainly better suited to the "remember" portion. I do wish often that I was better at that part. Regard, Allan
Parent - - By js55 (*****) Date 09-20-2007 16:52
jon,
"there are NONE among us, not a single one, who see's or know's all things about our field at all times!!!"

Thats why we're here.

As I sometimes like to say, 'the more I seem to learn, the less I seem to know'.

So, using this as a premise, I suppose it could be argued that the more knowledgeable contributors in the forum, of which there are many, have contributed most to our ignorance. LOL!!!!
Parent - - By jon20013 (*****) Date 09-20-2007 16:56
js55, aevald... "So, using this as a premise, I suppose it could be argued that the more knowledgeable contributors in the forum, of which there are many, have contributed most to our ignorance."

When I was younger, I used to always hear "So and so has forgotten more than you'll ever know about..." (name a subject)... I now understand, and very well put by both of you old-timers, lol!!!!
Parent - - By js55 (*****) Date 09-20-2007 17:12
Old timer?????  Who you callin old ti,

Sorry. I nodded off for a second. What were we talking about?
Parent - By ssbn727 (*****) Date 09-20-2007 18:27
ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
Hmmmmm... What did I miss?? SOSDD!!! Okay, I'm going back to my POWER nap. ;)

Respectfully,
Henry
Parent - - By aevald (*****) Date 09-20-2007 18:27
Hello again Jon, I'm still laughing. When I was 20, I used to think 30 was an "old timer". Now that I'm ???, Well, I don't know anymore. Regards, Allan
Parent - By jon20013 (*****) Date 09-20-2007 18:29
aevald, I'm laughing too, in my "era" the common saying among "kids" my age was "I hope I die before I turn 30"... lol, I guess I should be dust blowing in the wind by now!!! ;-)
Up Topic Welding Industry / Technical Discussions / Deletion of weld process

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