thickness

By exwelder1@yahoo Date 08-20-2008 02:07

I am yanking my hair out over this section IX stuff. I am definetly not ready for this. I on the other hand have done a lot of work in 1104. Man what a huge difference. Any help would be appreciated. I think I need to attend a seminar or somthing.

By pipewelder_1999 (****)

Date 08-20-2008 03:30

Base metal thickness does NOT apply to welder performance qualification if you are using ASME Sec IX. Diameter and P Number but no thickness Min or Max. Only deposited weld metal thickness and that value is a max.

By exwelder1@yahoo Date 08-20-2008 14:03

Can you elaborate on that so even a dummy like me can understand. I really do not understand the correlation between the PQR/WPS and the WQT.
PQR was done on 2" x .218 SA-106 Gr. B How does that correlate to the WPS and the WQT.
I do understand limitations in diameter. But the thickness range that a welder is qualified to is killing me.

By 3.1 Inspector Date 08-20-2008 14:27

Be carefull with your hair, you might loose it soon enough :)

I will do my best to sort it out for you.

A pWPS (preliminary welding procedure specification) is written by the welding engineer, based on that pWPS you weld a test coupon. You record all relevant data during welding.
Thoose data is then written on the PQR (procedure qualification record) based on the data recorded you can the write a WPS (welding procedure specefication) within the parameters outlined in the code you are testing to.

When all that is in place you will have to certify the welder with a WQT (welding qualification test) the PQR and WQT can be done on the same test coupon.

As far as I remember thickness is not an issue in regards to a WQT, but the deposited weld metal is.
If the welder does his test on a - this is an example - 2 inch thick plate/pipe, he deposit 2 inch weld metal (he deposit the same thickness as the coupon is thick - NOT taking into account depth of penetration or weld reinforcement)
If - still example - the code state that when depositing 2 inch of weld metal, the welder will be qualified x2 (4 inch) which mean that he can ONLY deposit 4 inch of weld metal, but in theory the groove can be 8 inch thick - but he is only allowed to weld up tp 4 inch - and another welder has to take over :)

Note that the above is only an example...

Now that I think about it, I think that if the welder deposit more than 3 layers he is qualified unlimited, I am not sure on this one....I suddenly remember something about 13mm.
It might be if the coupon's thickness is more than 13mm and he deposit a minimum of 3 layers, he is qulified unlimited.

If I left something out, I am sure I will be corrected by other members :)

By ctacker (****)

Date 08-21-2008 04:09

"If - still example - the code state that when depositing 2 inch of weld metal, the welder will be qualified x2 (4 inch) which mean that he can ONLY deposit 4 inch of weld metal, but in theory the groove can be 8 inch thick - but he is only allowed to weld up to 4 inch - and another welder has to take over "

I thought (I'm no expert) that a weld deposit of 3 passes would qualify a welder for 3/16 to whatever thickness was required.
I can look tomorrow when I have a codebook handy.

Also, I need to qualify a few welders for 2" pipe. the engineer sent me some 2-3/8 OD 1/4" wall coupons. the WPS says I need the root (open root) and 1 pass GTAW and the remainder SMAW. That will put approx 1/8" filler GTAW & 1/8" SMAW. the coupons are the same as the job we will be doing.
Am I right by limiting the production welds to 1/4" weld deposit for each GTAW & SMAW.

1 more thing, has anyone ever done an open root on the pipe listed above with GTAW and a preheat of 400F? seems a bit high to me.(material is ASTM A335 and ASTM A182)

By 3.1 Inspector Date 08-21-2008 06:26

which is why i wrote....

Now that I think about it, I think that if the welder deposit more than 3 layers he is qualified unlimited, I am not sure on this one....I suddenly remember something about 13mm.
It might be if the coupon's thickness is more than 13mm and he deposit a minimum of 3 layers, he is qulified unlimited.

By pipewelder_1999 (****)

Date 08-20-2008 14:49 Edited 08-20-2008 15:58

Not a "dummy" at all. This is a subject that I think many people are confused on.

Here are some background facts. [edit] Based on what I understand the code to say in many cases. I have on more than one occasion come to realize that interpretations from someone on a code committee may very well be different than mine. I strongly suggest looking these ideas I have stated below to assure that what YOU do is correct. The statements below are made in the context of this thread[/edit]

1) The ranges of qualification for performance based on the test below are different for the welder than the procedure.
2) The welder for instance has no limit on the maximum base metal thickness he/she can weld on. The WPS is limited to 2T.
3) The welder can weld ANY thickness but can only deposit up to 2t of the deposited metal used for each process.
4) The procedure can be written for 7018 open root but the welder must use GTAW (I am making an assumption that the test was GTAW/SMAW)
5) The welder can weld on Pnumbers 1thru11 amd Nickel alloys of P4X p numbers. The WPS is limited to P1 to P1
6) The welder can weld on material with ANY amount of Preheat, Interpass, PWHT. The WPS may need to be requalified depending upon the changes and requirements for impact testing.
7) The welder must weld uphill. The WPS could be written for downhill (unless impact testing is an issue )
8) For performance qualification ASME Lists 7 variables for SMAW. For Procedure qualification there are 11 essential, 17 Non-Essential, and 10 Supplementary essential variables.
9) The Welder is qualified down to 1" OD but the WPS may be written to any diameter.
10) If a welder deposits 1/2" of weld metal with a minimum of 3 passes he is qualifiedd for unlimited deposited weld metal, the procedure in the same case would be limitedd to 2 times t hat thickness or less depending on the process.

So as you can see there are some differences. Base metal thickness is NOT listed as a variable for performance qualification. Diamter is.

Hope this helps. If I had more time i'd throw some code paragraphs in there. Its in there .

Gerald

By exwelder1@yahoo Date 08-20-2008 15:39

Very well put. Gerald I think the more that I work with these. I will get a better understanding of the code and its requirements. As of now that information is a whole lot more than I was able to put together on my own. very much appreciated
Thanks.
Joe

By js55

Date 08-20-2008 15:51

Section IX is tough. Due mostly to the numerous cross references. Its difficult to follow a single reference thread to completion. I don't believe I've ever been able to do it. :) I just concluded that I have enough info to do what I need to do.

By exwelder1@yahoo Date 08-20-2008 15:49

So in essence if I give a 2" x .218 test. Downhill with 6010+ root and a 7010 filler bead and cap the maximum weld thickness would be 0.436" because it is the same process. That should qualify welders to weld on any size pipe up to 24". But if the wall thickness on the production welds to be made exceed 0.436" I would have to upgrade the welders qualifications to a thicker coupon. Is that correct?

By pipewelder_1999 (****)

Date 08-20-2008 15:52

There is no MAX diameter. Only a minimum.

If the wall thickness is greater than .436 then you either have to requalifiy the welder OR use more than one welder on a joint.

By jsdwelder (***)

Date 08-20-2008 16:38

I understand WHAT the max. weld thickness is per the code. What I dont understand is........ WHY? Why if, for example a guy is qaulified to weld up to 1/2" thick and he is welding on something that is 1" thick, why can he not finish the remaining 1/2"???. Can anyone explian this. Must be a reason......

By js55

Date 08-20-2008 16:47

ASME Section IX made judgement that this was essentially the threshold range. The old thickness requirement was 3/4" but it was argued to reduce it as long as a min number of passes was involved. Difficult to get 3 (say SMAW or FCAW) passes on .218/.250 wall (keep in mind the 2t) without grinding. So the threshold was established at 1/2" with the multipass proviso. The judgment was made also that anything over 3 passes does not require any more skill than 3 passes. Its just redundancy. And the idea is not to make the welder weld until they screw up.

By pipewelder_1999 (****)

Date 08-20-2008 17:03

Another thing that strikes me as odd in relation to this is that as the welder test gets thicker, the acceptance criteria gets more relaxed for radiography.

If I can deposit 1/2" of weld metal once with results that meet the requirements for that thickness, I can surely do it on thicker material with larger allowed indications.

It is possible that I have missed something but in my opinion the thicker, the easier. More heat, flatter beads, etc..

The code doesn't reflect that but I am only an observer in these matters. I have had a few people puff up in the past and t ell me "Im a heavy wall welder". I just grin and remember those big ole porosity charts.

By jsdwelder (***)

Date 08-22-2008 10:52

I guess I'm still missing something as well. To me its kind of like saying that we (the code) trust your skill level for the first half of the joint, but not the rest of it. I am of the same opinion as pipewelder 1999 in that if I have the skill to do what most welders would consider the hardest part, ie.-root pass, hot pass, I surely have the skills finish the joint using the same process and filler material. Sort of like saying to any other worker that we have faith in you to do your job Monday through Wednesday, but were going to nedd to get someone else to do your job on Thursday and Friday.

By js55

Date 08-22-2008 14:31

"It is possible that I have missed something"

Yes.
The mechanicals. Performance qualification does not rely on radiography. In fact, radiography isn't even necessary under many codes, but mechanicals always are, the only exception that I can think of is the accomodation of performence tests with production welds for machine processes. And as you increase thickness you also increase the possibility of a defect that could cause the failure of your bends.
Though I would agree with you that the idea of bragging about 'heavy wall welder' is silly. The 2" 80 was always considered the tougher of the two tests under ASME. But since the code change to 1/2" deposit the "monster" coupons became popular.

By pipewelder_1999 (****)

Date 08-22-2008 15:47 Edited 08-22-2008 15:52

I understand the mechanicals as the acceptance criteria is the same however is it more likely that the longer a person welds,, the more likely he/she is to have a defect ?

I was speaking in reference to oASME Sec IX in which radiography is allowed for most processes and in my experience is used the majority of times. Other codes may prohibit performance testing to bends only. I just haven't used any except in cases where the process warranted mechanicals.

I think thickness is related to the deposited amount and the idea that after 1/2" of deposited metal, the welder has it figured out is taken into account. I was just commenting more on the "heavy wall" idea.