Has anyone come across or written a WPS for P-1 to P-1, requiring ER308 SS weld wire (SFA5.9)? Why would this be done rather than using a SFA 5.18 or SFA 5.22 wire? What would be some of the major issues with doing so if there are any?
For GTAW certification, some companies feel they need to use SS wire (F-6). So some tests are P-1 to P-1 with ER 3XX wire. As far as a production weld, I can't think of a reason but that means little.
G Austin
www.weldinginspectionsvcs.com
There could be any number of valid reasons an employer would do this, but it may also be a case of ignorance. On possible valid reason may involve WPS qualification under ASME IX requirements, i.e., a change in "A-Number" QW-404.5. Without knowing the application or governing standard (I assume the standard is ASME since your question deals with P-Numbers) but it's difficult to say so one can only speculate from this forum. There would be no major issues with doing so except that the WPS, unless supported by multiple PQR's would be limited to using an F6, A8 filler metal.
Ah, sorry, missed the Section IX part of your posting ~ I should have had a V-8 (smacks himself in the head!) My response is the same; probably involves the A-number under ASME IX Essential Variables.
I must agree with Gerald, that it is probably to allow the company to qualify welders at a slightly reduced cost.
While it is theoretically so that qualifying a welder with a carbon steel pipe (P1) using a carbon steel filler, will qualify the welder to weld S/Steel, many fabricators (& end users) would rather see for themselves if the welder can actually pass the test applying backing gas. Often, the welder does not manage to produce the weld without oxidation in the root.
To eliminate the cost of the S/Steel pipes, they use C/Steel pipes with only the S/Steel filler.
Can't think of another GOOD reason to weld P1-P1 using S/Steel filler.
Regards
Niekie Jooste
Nieke;
I'm not sure I agree with the welder qualification issue. While it's certainly possible the question was regarding the WPS so I'll stick with my original "educated guess" that it has more to do with the essential variable addressing a change in "A-Number" ~ what do you think?
I think the welder qualification issue is valid, as a welder must follow a qualified WPS to be qualified in accordance with ASME IX
Agree, but doubtful an employer would qualify a WPS which uses carbon steel base and stainless steel filller simply to assure his welder can properly deposit ss filler metal.
The ASME Code doesn't have any variable required for the welder in this particular case but there is an essential variable for the WPS and that is the change of A-Number. Otherwise the employer could simply use carbon steel with any F6 electrode and use the WPS for joining P1 through P11, P3x, P4x per QW-422, etc. I'm sticking with the A-Number being the employer wanted to use ss filler - the base metal was cs because it is obviously less expensive and allowed by QW-420 to be P1 when qualifying for the other P-Numbers above.
Interesting discussion this question has started!
Thank you for all replys. Since only the ER3xx weld wire is specified in the WPS that requires the welder to weld with this stainless wire in production, even if it is contrary to everything they have ever been taught. Perhaps the real reason this wire is qualified with P-1 material is so that when the welder screws up and uses the wrong weld wire, they do not need to remove the weld, only change the requirement/ WPS specified on the drawing. I am interested in hearing about any known failures resulting from this practice. (carburization, corrosion, etc.)
First, let me say that from engineering stand point I see no valid reason why you would qualify a WPS using P1 to P1 material and welding it with ER308. In accordance with QW-424.1 (below) this WPS is only good to weld P1 to P1 using a stainless steel weld wire in production (cannot change A number). This is not (in my mind) good engineering judgment. One reason is, there is a significant difference in thermal expansion between the S.S weld metal and the carbon steel base metal (S.S. has a thermal expansion about 30% greater than Carbon steel). This will force the entire thermal mismatch onto the weaker carbon steel. This might lead to premature failure of the base metal in the HAZ.
Looking at the Schaeffler Diagram, when welding P1 to P1 (I used A106 material and ER308 from ESAB) the final composition will fall within the A+M region. This indicates that the final weld metal composition will be Austenite + Martensite. The likelihood of the weld cracking is very good since there is no Ferrite present to prevent hot cracking of the S.S weld metal.
The only reason you would qualify a WPS this way is to test your welders with the S.S. weld wire. Section IX says that if a welder qualifies using P1 material he is also qualified P1 –P11 and so on. The catch is the welder cannot weld P8 material because he is not qualified with the proper filler metal. Basically, the WPS is useless for production welding in my mind and can only be used to qualify welders. Why would you go through the effort and expense to qualify a WPS you cannot or should not use in production.
QW-424.1
One metal from a P-Number to any metal from the same P-Number Qualifies Any metals assigned that P-Number
One metal from a P-Number to any metal from any other P-Number Qualifies any metal assigned the first P-Number to any metal assigned the second P-Number
Hope this helps some.
Mark M
You stated above >>
.....The catch is the welder cannot weld P8 material because he is not qualified with the proper filler metal. ......
Help me out, isn't ER308 an F6 filler metal and for GTAW the only requirement for filler metal is "F Number" and addition or deletion of filler metal.
As far as I can see, there is no need to test a welder with ER 308 wire for butt joints. If you wan't to see if he can weld SS get a piece and let him run a bead or two. SMAW this is different.
G Austin
A-Numbers are different. A change in A number will require requalification of the WPS. See QW-256 for GTAW and QW404.5. ER308 = A8, ER70S = A1. Therfore you cannot test the welder using A8 filler if the WPS was qualifed with A1 filler.
I understand the part about the WPS. Your statement indicated the WELDER was not qualified.
QW 423.1 plainly says "Base material used for welder qualification may be substituted for the P Number material SPECIFIED in the WPS in accordance with the foillowing ..... BLa Bla Bla
QW 423.1 is referred to by QW 403.18 which is referred to by the chart QW 356.
The base metal filler metal combination in the WPS is completely irrelavant to the performance qualification for those materials listed.
If we were just talking about a WPS then A number and P number mean one thing. A P-8 to AP-8 WPS could be used and since the base metals can be substituted as indicated by QW 423.1, P-1 material coould be used.
Of course if you did that and purged the root then the welder would only be qualified to weld with a purge, therefore to reduce the overall cost of a relatively simple process, test the welder using CS base metal, CS filler metal, No purge and said welder is qualifed to weld on P-8 to P-8 material with or without purge within the other restictions of the welder performance qualification test.
If you want to see if he can weld stainless, give him a piece of material that you consider to represent the "problems" associated with stainless and see if he can hack it.
There is no need to qualify a WPS for testing a welder using carbon steel base metal and SS filler metal for GTAW.
Good day
Gerald Austin
Interesting question.
The use of a stainless steel bare solid wire is fairly common for welder performance qualification with GTAW on P-1 test coupons. As previously mentioned by others, some owners/companies want to be sure that the welder can handle a purge, and can complete the root and hot pass without concavity or oxidation of the root. Some companies have qualified a P-1 to P-1 WPS specifically for this, but some just use a qualified P-1 to P-8 WPS.
Over the years I have seen a few other WPSs qualified for joining P-1 to P-1 materials that required stainless wires, but they were for special repair applications (for repairs on piping systems that could not be completely isolated). They were not for "typical" production welding.
I have also seen other sets of WPSs qualified for joining composite piping (stainless lined, carbon steel pipe) using stainless steel consumables for the complete joint.
I see several good guesses as to why a company might use such a WPS. Why don't you just ask them why they did it? If you mention that you haven't run across this before and are curious why they do it, I doubt you'll get anyone ticked off at you. Or was this just a hypothetical question?
Marty
I always look for your replies for a touch of wisdom Marty and you always seem to provide it. It must come from the old AS-19 weld shop training you got as a young sailor. What was our old HT1 Lead petty officers name?
HT2 (frocked to HT1) Casey
Which one? Henry Young? Dave Albert? Hodges?
Dave Albert, thanks, now I can finally sleep at night. He was a good LPO, wise beyond his years.
Thanks Marty
Have a great Christmas!
I can explain why I qualified a P-1 to P-1 WPS with SS filler wire: to use in combination with a P-8 to P-8 WPS when welding composite pipe with a SS core or sleeve. Outside the core/sleeve the pipe was SA-106. So the P-8/P-8 WPS was used for the "T" of the SS core and the P-1/P-1 WPS with SS filler was used for the remainder of the fill.
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