Not logged inAmerican Welding Society Forum
Forum AWS Website Help Search Login
Up Topic Welding Industry / ASME Codes / Pulsing-Spray Transfer ASME Section IX
- - By W3ldEngin33r Date 08-14-2015 15:30
I am 95% sure Im correct but I want to make sure I'm 100%. I have a GMAW WPS that was written to "Not Permit" pulsing on the procedure, but upon investigation I have found that we are currently running a Pulsing Gas Mixture and I feel it would be better for our welders to pulse their welds and also omit a backing. I am new to ASME so bear with me.

My question is, does changing a WPS that originally "did not permit" pulsing to allow pulsing warrant requalification per ASME section IX?

Also, I have noticed that omiting a backing is a non-essential variable. Does this mean I dont have to requalify the WPS because of this classification of variable?

Im certain if we stay within the speccified transfer mode that the pulsing will be allowed and also the removal of the backing is of no concern as well. But like I said before I need to be 100% certain.
Parent - - By In Tension (**) Date 08-14-2015 17:54
It's true that in Section IX both a change from spray to pulsed spray and the omission of backing are both non-essential variables per QW-255.  So the simple answer is that yes, from the information you've provided and with all other things being equal, you should not have to requalify.  The complex answer is that all other things are unlikely to remain equal.  Here are some things to think about if you haven't already.  Keep in mind I don't have Section IX in front of me so any or all of the following may be a figment of my imagination...
That you are using backing leads me to believe that the final weldment is to be CJP from one side only.  So with the omission of backing it's likely you'll have an open root weld. 
If you plan to GMAW-S the root gap you must requalify the procedure due to change in transfer mode.  Also keep in mind GMAW-S is considered a separate process and will affect your welder qualifications, calculation of thickness deposited, thickness qualified, etc.
Deletion of backing is an essential variable for welder performance.  If they are not already qualified for the open root you must requalify the welders.
What kind of metal and product form are you welding?  Will it require backing gas?  If so, you must requalify the procedure.
Is impact testing involved?  No doubt you will have different heat input levels with the pulsed spray and may have to requalify the procedure.
Why was pulsing explicitly not permitted in the WPS in the first place?  Did you inherit the procedure from the previous welding engineer?  Get to the bottom of these things before you follow through so you don't repeat mistakes that somebody else had to learn the hard way.
Noel
Parent - - By Lawrence (*****) Date 08-14-2015 17:59
I really like your responses In Tension...

To the OP

What exactly is a "Pulsing Gas Mixture" ??
Parent - - By W3ldEngin33r Date 08-14-2015 18:29
66% Ar, 33% He, 1% CO2 has always given me a more stable arc when using GMAW-P (Spray Pulse) so I automatically refer to that combination as a pulsing mixture. My apologies for the confusion.
Parent - By kcd616 (***) Date 08-14-2015 18:50
Lawrence and Al
will tell me I am wrong
but I really like that gas mix
very interesting
sincerely,
Kent
Parent - - By Lawrence (*****) Date 08-15-2015 19:25
GMAWP on austinetic stainless can also be done with excellent results with the simple two part gas mixture of 98/2  Ar/Co2.

If you are doing a high volume of production, the cost of helium becomes more and more relevant.

The open roots without backing with 304?   I've seen mixed results... STT and RMD both have done very nicely (but are short circuiting) and also can perform well on open roots with the two part gas mentioned above .

It's not that Kent is wrong... The gas mix he likes is a good one. (As long as somebody else is paying for it).
Parent - By aevald (*****) Date 08-15-2015 20:43
Lawrence you're right about the gas choices when someone else is paying. Students are always asking what to set their flow meters to. Besides having the conversations about verifying what is stated on the WPS and going with those settings, I will tell them that when I am at home welding on my personal stuff it amounts to the minimum flow rate that won't display/yield adverse results. After all, the more things that I can weld without a cylinder change, the more money that stays in my pocket. Best regards, Allan
Parent - By kcd616 (***) Date 08-15-2015 22:22
Lawrence,
just put this in my forever file:wink:
It's not that Kent is wrong.:eek::lol::smile:
but I do love helium
guess it is still what I learned on
but you guys are pulling me away from it:eek:
sincerely,
Kent
Parent - - By W3ldEngin33r Date 08-14-2015 18:26
Thank you for your response. Your knowledge is helping me understand Section IX just a little bit more. I was not planning on using GMAW-S the root gap as I had already considered that requalification was needed for that type of process.

I have spoken with one of my colleagues who is more familiar with ASME than myself and he did inform me of the Welder Qualification vs. backing omission issue. This will not likely cause an uproar as I will only need to requalify 2-3 welders for now.

The metal being joined is 304 SS so a backing gas is not needed. And I also looked into if impact testing is involved and the answer is a resounding "No".

I did inherit all of my procedures from the previous welding engineer and now I am currently revising all of them to help prevent confusion amongst myself and colleagues. If you have any other information on this matter I would gladly take your input. Thank you again.

Kyle
Parent - By dggggdzs Date 08-17-2015 09:12
a
Up Topic Welding Industry / ASME Codes / Pulsing-Spray Transfer ASME Section IX

Powered by mwForum 2.29.2 © 1999-2013 Markus Wichitill