D1.1 WPS/WPQT Question

By WeldMania Date 05-13-2015 14:32 Edited 05-13-2015 15:11

Dear Everyone,

i would like to get your input on somethings that are seriously confusing me to say the least, appreciate any help.

we are qualifying a Groove WPS for mild steel and ballistic (the welders will be qualified on fillet only).
now the ballistic is outside the scope of D1.1 (yield strength more than 100 ksi) however we'll use clause 4 and we got the necessary approval from the client.

now for mild steel we have qualified the WPS using square groove GMAW-S (2G, 3G, 4G), no problems there visual and mechanical are prefect. however when we wanted to qualify the welders on fillet 3F&4F (using what seems the only option Table 4.11 : (Figure 4.37) 12 mm thick option one fillet weld, 8 mm leg size)

it was impossible to get it to pass the macro (since we are using GMAW-S), we always had a nasty looking LOF at the root and sometimes the weld seemed to lay flat on the plate without fusion (ER70S-6).
we've tried every thing like for example:

1) single pass and multi-pass (3 passes) but still LOF "by the way dose d1.1 have limitation on using a single or multi pass to cover the 8 mm leg required, when qualifying a fillet WPS its clear from the table 4.4 but here i couldn't find any thing specifying single or multi"

2) we've tried changing from 90/10 to 75/25 (Ar/Co2) hoping the increase in Co2 might help agitate things up and help fusion but no luck.

3) of course weaving technique didn't work, we've tried triangular motion (making sure the wire is centered on the root when moving up and staying on the leading edge of the puddle) with no success.

4) cranking the parameter as high as short circuit allows, still the same.

i think a good preheat would definitely help the 12 mm thickness but the WPS passed without it.
lastly assuming the fillet passed (somehow) is it possible that the fillet range qualified is 1/8 to "Unlimited", shouldn't there be some kind of restriction on GMAW-S thickness qualified.

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now for ballistic it's basically the same GMAW-S (2G, 3G, 4G) V-Groove and welders on fillet 3F&4F, wire used ER100S-G (manufacturer recommendation).

however here the PQR is failing in face/root Bends (full fracture) and tensile (brittle at the weld UTS for the 3 positions rang between 850-900 N/mm2 {123,281 - 130,533 PSI}) the only thing acceptable is the macros.

the base material Tensile strength is (750 - 950 N/mm2 {108,778 - 137,785 PSI}) in a manufacturer (SSAB) Data Sheet says no preheat is required and under HEAT TREATMENT the following:

''Stress relief annealing should be carried out within the temperature
range of 530 - 580°C. Heat treatment above this
range, e.g. normalizing and hot forming, reduces the strength
and should be avoided''

and in D1.1 nothing on HT.

and for welders (we didn't reach there yet)but i know we are gonna face the same LAF issue in the fillet.
and the manufacturer supply plate thickness up to 10 mm max, no 12 mm for Figure 4.37.

i know this might be too much for my very first post but i am lost here.
i am counting on the fact that i am still a noob in D1.1 and there is definitely something i am missing that you guys can help point out.

Many Thanks.
Regards.

By Lawrence (*****)

Date 05-13-2015 15:14 Edited 05-13-2015 15:31

12 MM is pretty thick for short circuit GMAW.   Can it be done?   Yes.

Is Spray transfer a better choice...? Yes

Is GMAWP a better choice...?    Yes

But you didn't ask for that kind of help.

11 Easy Steps :)
To get your fillets to fuse at the root and pass macros:
1.   Contact tip to extend 1/8" past the nozzle
2.   Contact tip to work distance 1/4 - 3/8" (very tight)
3.   Go back to your 90/10 gas
4.   .035 Lincoln L56 or L59 (ER70S-6)
5.   215-240 IPM WFS
6.   17-18.5 volts
7.   1/4" max leg length fillet stringer beads
8. 10-15 degree DRAG travel angle on the weld gun.
9.   Limit side to side oscillation by the operator to 2 electrode diameters to flatten out the puddle
10. NO FORWARD AND BACK WHIPPING OF THE GUN... STRAIGHT STRINGERS.
11.   If your power supply has inductance controls... Choose a high value (fewer short circuits per second)

Edit:   Welcome to the Forum !
\
.

By WeldMania Date 05-13-2015 15:38 Edited 05-13-2015 16:09

Mr. Lawrence

Many thanks for the prompt response. we will definitely try out your recommendation.
but to address the first few lines from your reply:

*for the 12 mm thickness i totally agree with you that it is a bit thick for GMAW-S , but that was the required thickness as per Table 4.11 : (Figure 4.37) for welder qualification with an 8 mm leg size..... as a side comment: if we are allowed to choose a different thickness for fillet weld that would be awesome (kindly reference the code paragraph) because i wonder how we will determine the range qualified for the plate thickness and for the leg size?

*the reason we choose GMAW-S and not spray because we will test the welders on 3F and 4F to cover all positions.

*we have tried running a straight bead with no luck (however i will advise the welder to try again using the other tips you provided)

thanks again.

By 803056

Date 05-13-2015 18:21

Since you are welding to AWS D1.1, and since GMAW-S is not prequalified, I assume you qualified the WPS per Clause 4 and verified the parameters for fillet welds per Table 4.4 and figure 4.19. That being the case, why are your welders experience such a problem if they follow the WPS?

Make sure they are not "pushing" the weld pool.

Sounds similar to the question you asked a few days ago Lawrence. Back to your question, I apologize for net getting back, but I've been swamped. This gets to the crux of the problem. D1.1 is rather hazy; other structural welding codes are more explicit.

Al

By WeldMania Date 05-13-2015 19:03

for mild steel i did qualify the WPS by welding an open root square groove test plate on the PQR only (not fillet), and then proceeded to qualify the welders on fillet since Groove WPS will include the fillet in the range qualified using table 4.2 foot note d: ''CJP Groove weld qualification on any thickness or diameter shall qualify any size of fillet or PJP groove weld for any thickness or diameter''

i looked every where trying to find some kind of a restriction for this rule when the process is GMAW-S but couldn't, the only thing i found that places some kind of restriction on GMAW-S was in 4.20.1.1 "substitution of RT for guided bend test...allowed except for GMAWS -S"

By 803056

Date 05-13-2015 19:28 Edited 05-13-2015 19:45

If you cannot obtain the required weld size using the range of parameters listed by the WPS (based on the ranges used to weld the plate test assembly), then the WPS is not adequate as written.

Recommendation: qualify the fillet sample first, per Figure 4.19. Using those parameters, weld the test plate to demonstrate the proposed WPS (using fillet weld parameters) is capable of producing the required mechanical properties, i.e., tensile strength, weld soundness, etc.

Welding the test plate first demonstrates those parameters will produce the required mechanical, but now one is stuck with welding parameter ranges that cannot meet production needs. One is now stuck in the swamp (or desert) with no way out.

The reason one qualifies the WPS in the first place is easily overlooked.

In this regards, D1.1 appears to presuppose the individual using the code is a welding engineer that already understands the principles of how and why a WPS is qualified. It is also one reason that AWS B5.1, Table 1 does not list developing and qualifying WPSs and PQRs as functions the CWI performs. The CWI is expected to witness the welding of the test coupon, he is expected to record data, but he is not expected to develop the welding documentation. Nothing on the CWI examination requires the candidate to develop welding documentation other than knowing where to enter specific information.

Some of the other AWS structural welding standards does a better job of defining how the WPS is qualified, but still, there are presumptions made by the code. For instance, one of the structural welding codes states the mechanical properties are demonstrated by welding a plate assembly, and the fillet weld assembly is for establishing the parameters for the fillet welds. It doesn't specify the sequence of events, that is left to the user to determine. The approach I mentioned, fillets first, followed by the plate assembly was suggested by one of the committee members. It makes sense to me.

Best regards - Al

By WeldMania Date 05-13-2015 20:49

you are correct in every thing you've said.

i have one last question (please bear with me, i am truly trying to wrap my brain around it)
forget that we want to qualify the welders on fillet. lets say after qualifying a square groove WPS/PQR we test the welders on the same square groove identical to the PQR arrangement (if he is good he will pass since it was demonstrated that it's doable during the WPS/PQR) and in my case the the PQR passed all the required tests.

as per the code rules the welder is automatically qualified to weld fillet max range (unlimited thickness) this is also true for the welder who welded the groove PQR test. however that's is not true for big thicknesses only because it is short circuit (due to its low heat input), if the process was SMAW/GMAW Spray (F,H) we wouldn't have a problem.

my point is if the WPS is qualified on a groove using GMAW-S there should be a limit on the fillet weld thickness qualified like for example 3 or 4 mm max above that the code might require a separate fillet WPS be qualified.

and the same applies for Figure 4.37, it doesn't give an alternative for welder qualification test using GMAW-S with a lower thickness and a more conservative range qualified compared to the 12 mm thick/ 8 mm leg size and max range unlimited.

i feel the code left Short Circuit in a bit of a gray area. some of the points above i think might be directed towards me from our client :eek:

and for the ballistic how can i test the welder on 12 mm required fillet if the highest thickness available from the manufacturer is 10 mm?

lastly could any one please advise if there is any book/reference i can buy that explains D1.1, i have the code clinic but it doesn't cover any thing in depth like for example Casti guide for ASME IX.

thank you.

By 803056

Date 05-13-2015 21:08

The best I can say is that no code is perfect. After all, humans are involved.

Next, the code stipulates the minimum requirements that must be met. It is the contractor's responsibility to take any further steps deemed prudent to ensure the products they manufacture will function and perform as intended. It is incumbent upon the manufacturer (all encompassing term for manufacturers, fabricators, installers, erectors, anyone providing a service, etc.) to exercise due diligence to ensure they meet all code requirements, local, state, or federal laws and regulations, etc.

It is presupposed that the employer assigns qualified individuals with the training, education, and experience to fulfill job assignments. So employers take their responsibilities seriously and others only go through the motions. The latter are not considering the long term ramifications of substandard products or ensuring their employees are satisfied with their jobs and they are working in a safe environment. These same companies are usually the ones that have limited longevity.

It isn't hard to look to the products coming out of different countries to see the ramifications of their well earned reputations. Once that reputation is earned, it isn't easy to change. The same is true of individuals.

I don't know it that helps or not, but it is the best I have to offer. One last word, if the employer doesn't have the necessary in-house expertise, it is their responsibility to hire a consultant to help guide them.

Best regards - Al

By WeldMania Date 05-13-2015 21:14

Dear Mr. Al

again i 100% agree with you.
thank you very much for your feed back and time, truly appreciated.

Best Regards