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Up Topic Welding Industry / General Welding Discussion / undercut vert down
- - By hogan (****) Date 03-17-2006 16:16
working to D1.1 you are allowed to fix undercut on a 3g weld downhill. do you need a supporting pqr for the change in progression?
Parent - - By jon20013 (*****) Date 03-18-2006 10:15
If I recollect correctly, the answer is no.
Parent - - By Shane Feder (****) Date 03-19-2006 06:45
Hello Jon,
I have always had concerns about that clause in the code.
Hate to think how many times I have seen welds with undercut "doctored"with a vertical down wash.
As we all know some processes have low penetrating qualities so what are you actually doing when you are covering undercut with vertical down, you are "hiding"the undercut. You cannot guarantee 100% that you have burnt out the undercut so you may very well have a stress raiser left in the weld just below the surface.
Others may say that they grind it out and then reweld it but as an ex welder I can say I have seen hundreds of examples of welding directly over undercut and never once seen it ground out first.
Also, in response to your reply I have a couple of questions.
Firstly, if you are welding vertical up with E71T-1 or E7018 and you get undercut how are you going to repair.? Those two consumables are not recommended to be used vertical down, so we have some other consumable introduced into the weld (from past experience it is usually GMAW or an E6012/13)
Whether or not you require a PQR I don't know, will trust your memory on that one.
Secondly, how do you go with welder qualification?
As I mentioned earlier as an inspector it has always concerned me,I go to do a visual inspection on an item and see vertical up FCAW with bits of GMAW or SMAW along the edges and it doesn't instil me with a lot of confidence.
Your thoughts ?
Regards,
Shane
Parent - - By texredneck (**) Date 03-19-2006 07:05
Personally as a welder I am agast by this. I figure do it right. If not fix it right....
Parent - By vonash (**) Date 03-19-2006 16:36
Yes, per Table 4.5 (20).
Parent - - By jon20013 (*****) Date 03-20-2006 16:45
Hi Shane, sorry it's taken me a while to get back, I took the day off on Friday!

Regarding correction of undercutting by vertical down welding, I guess it really doesn't matter what my opinion is since the Code(s) generally permit it. But, since you asked, I guess my observation has been that a fairly large percentage of undercutting I've seen through the years has been relatively rounded at the very bottom of the undercutting, thus reducing the stress notch effect. I remember some years back, the Naval Joining Center did a study of intentionally applying fairly shallow undercut with a rounded profile at the toe of fillet welds; tests showed that this actually worked to enhance the "strength" of the welds. (Naturally, this was done mechanically rather than thermally to be able to control the amount and shape).

From my recollection, the correction by vertical down (at least in D1.1)stemmed from one old timer Committee Member who was a pipeliner and a major player on one of the large producers of filler metal. In fact, if you look at the Lincoln Welding Manual, you may still see vertical down referenced quite often.

As for the mechanical effect, I guess unless the undercutting is gross, my opinion would be the vertical down is more or less a cosmetic fix. So, for what its worth, there's my 2 cents!

By the way, I don't remember as far as D1.1 goes but ASME IX allows the welder who was qualified up to weld down for repair of undercut or weld root when the root is to be backgouged.
Parent - - By MBlaha (***) Date 03-21-2006 02:31
Jon:

We are working under D1.1 and ASME section 9 and we do allow downhill with 7018 to repair undercut. According to D1.1, this is allowable. I will look in the book tomorrow to see exactly where to find this. I have it tabed.

Mike
Parent - - By swnorris (****) Date 03-21-2006 11:20
Mike,

You are correct. 3.7.1 indicates that undercut may be repaired via vertical down as long as preheat requirements are met, but vertical down undercut repair cannot be made if the temperature is less than 70 degrees F.
Parent - - By MBlaha (***) Date 03-21-2006 11:46
SWNORIS
Thank you. I forgot to mention we do require them to preheat before they fill in the undercut. The amount of undercut I am finding now has greatly diminished along with the arc marks, etc. ever since it was made know to the welders that these things are unacceptable and of course after having to drag a lead and air hose back to areas they have already welded and moved on thinking everything was good enough. I was tagged with a new nickname for a while, (paintstick LOL) but the welders have now gotten on board and quality has greatly improved. I think another thing that helped was making the arc marks on a piece of A36, grinding it out, polishing it, and bending it to show what they are doing when they leave them. Again, thanks to all of you that contributed to that post.

Have a nice day

Mike
Parent - - By jon20013 (*****) Date 03-21-2006 14:31
You know, a lot depends on how we communicate to our welders as inspectors, managers, engineers.

I've always found that if we treat our welders with the respect they deserve, and inform them of what we need to accept a weld, they will most often be happy to provide it.

No welder likes rework, so I tend to make extra efforts in my shop to educate the welders as to whats acceptable and also provide reasons why certain things are unacceptable. Being the lazy sort, it tends to make my job a lot simpler in the long run!
Parent - By jwright650 (*****) Date 03-21-2006 15:12
My findings have been the same as yours :)
John Wright
Parent - - By MBlaha (***) Date 03-22-2006 02:16
While I have not been inspecting as long as you Jon, I did find the same thing very quickly. What is expected, and a job well done works wonders when they are performing up to code works wonders. In plain simple words, respect. And yes, it allows me to get lazy too, as now all I have to do is go through one time, and everything they know I am looking for is taken care of before I get there.

Mike
Parent - By swnorris (****) Date 03-22-2006 11:19
Our goal is to build the quality into the work. not to inspect the quality into the work.
Parent - - By jon20013 (*****) Date 03-23-2006 21:00
Hey Shane, hope you survived the cyclone with no damages, haven't heard from you in a while a thought you were in Northern Queensland?
Parent - - By Shane Feder (****) Date 03-23-2006 23:48
Hi Jon,
No luckily enough we were a bit further south. Tropical Cyclone Larry completely destroyed several towns about 6 hours north of here and Cyclone Wati is presently just sitting out to sea gathering strength.No one knows which way she is going to head. As you guys are well aware with your hurricanes and tornadoes ol' mother nature can be pretty unpredictable.
Regards,
Shane
Parent - By jon20013 (*****) Date 03-24-2006 10:21
Yeah, and she keeps getting nastier every year it seems. We'll keep you in our thoughts, Shane and will hope for the best!
Parent - - By henri (*) Date 03-23-2006 17:51
Check D1.1 table 4.5 item 31 for the WPS/PQR and Table 4.11(4.10 in 2000 edition) item 6 for the welder.
Parent - By vonash (**) Date 03-27-2006 00:44
Again yes,
AWS allows undercut repair downhill without re-qualification of the WPS, however the PQR only documents uphill welding for the WPS, 'cos that's what is allowed by the code. Yes a simple downhill fill for undercut is provided for by AWS D1.1; record, record, record. Your PQR is the record of your welding procedures, geometry, techniques and materials utilized in your project.
Up Topic Welding Industry / General Welding Discussion / undercut vert down

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