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Up Topic American Welding Society Services / Technical Standards & Publications / Change in welding current polarity
- - By Nalla (***) Date 05-27-2013 11:04
Dear Experts

Question:
How does change in Welding Current/Polarity  ( AC , DC+VE , DC-VE )effects the Mechanical properties at the weld metal and HAZ?

Pls share your expertise with ref. to code and/or specification
Working Codes - AWS D1.1 & ASME B31.3

Weld Process used - SMAW , GTAW , FCAW , SAW  & GTAW/SMAW,  FCAW/SAW
Base Material - Structure - ASTM A131 EH36 Group II Material
Base Material - Piping - ASTM A106 GR B  & ASTM A333 Grade 6

Yes, as per AWS D1.1 Table 4.5- Change in Current and/or Polarity is essential variable which require PQR re-qualification.
The same applicable to ASME Sect IX/ASME B31.3.
Cannot just re-edit the WPS and use it.

But really have tough time convincing fabrication shop and management for re-qualification.
I need to put things in simple lay-man terms.

Thanks
Parent - - By 803056 (*****) Date 05-27-2013 17:51 Edited 05-28-2013 03:17
You can lead a horse to water, but you cannot make it wear a bikini.

It is a code requirement, plain and simple. There is no need for you to justify it. There is no reason to justify it.

The law says you cannot walk up to someone and cut off their finger for no reason. You do not have to justify the law, it is what it is.

However, if you need to justify the reasons for such a requirement for your piece of mind, try welding a CJP groove in carbon steel with E7018 using DCEN. Try welding a CJP on 1/2 inch thick aluminum using GTAW with pure tungsten using DCEP. For that matter, try it on carbon steel. Try using GMAW on the carbon steel using the wrong polarity. It will not take long to see the difference a change in the polarity will make or how a switch from DC to AC with an electrode intended for use with DC will make in the resulting weld.

I don't believe there are too many welders  that would question why current and polarity are included as welding variables. Management; they are a different story all together. The reason they are in management positions is because they can't do the work to begin with. When they screw up, they get promoted in hopes they will stumble into a position where they do not screw something up. Have you ever watched a CEO or someone at the executive level drive a nail into a board? They can't. They will hold five of six meetings, delegate the responsibility to someone in a lower position that will hire a carpenter (then they will ***** because the carpenter is over paid) and fire the carpenter if a mistake is made. If it turns out correct and looks like a work of art, the executive will take credit for the work "he did" and fire the carpenter that drove the nail home. 

Trying to educate an executive about AWS or ASME code requirements is like trying to teach a goldfish to read. The attention span of the executive or the goldfish is simply too short to learn anything. By the way, my money is on the goldfish if there is a choice.

Best regards - Al
Executive Director of Intergalactic Exploration and Exploitation
Parent - - By welderbrent (*****) Date 05-28-2013 17:22
Love your new job title there Al.  :lol: :roll:

Have a Great Day,  Brent
Parent - By 803056 (*****) Date 05-28-2013 20:00 Edited 05-28-2013 20:16
I thought the new job title was fitting. :cool:

Deleted - I though it was funny, but I thought it might offend someone.

Al
Parent - - By welderbrent (*****) Date 05-27-2013 20:20
Nalla,

I have to agree with Al.  The Code is what it is.  I don't have to justify or convince them of anything.

I would say you have more than likely run into this previously but let me point something out here:  They KNOW they have to do it.  They are just being rebellious, cheap, lazy, and irresponsible.  The same people will say 'I've been doing this for thirty years and never had to do that before' when you actually inspected a job for them just last year and made them do the same thing you are asking for now.  And they told you then they had never had to do it before.  They are just a bunch of liars and want to keep the money for themselves and hussle the job through to get paid. 

Now, let me tell you what I really think!!  ...Well, maybe not.  That was strong enough. 

Just tell them you are in the process of writing up the 'Non-Compliant' Report to turn in to all the chain of command agencies, the tone will more than likely change quickly.

Have a Great Day,  Brent
Parent - - By 46.00 (****) Date 05-28-2013 13:10
I agree with Al and Brent regards code requirement obviously, but also have a question, what or why would a change in welding polarity require a management response? I can see no financial gain and little or no time saved from a change in welding polarity for most of the processes you have mentioned?
Parent - - By welderbrent (*****) Date 05-28-2013 17:21
Glyn,

I know your question is actually for Nalla, but I would tend to think it is one of those companies whose leadership think they must micro-manage every aspect of the work and don't have a clue as to how, why, who, or where any of the work is specified and/or required.  Thus, it does not, from our point of view, require a management response; but it does from theirs. 

Have a Great Day,  Brent
Parent - By 46.00 (****) Date 05-28-2013 20:54
Hi Brent! maybe that is why our industry or even our economy is in the state it's in. Common sense is not that common!
Up Topic American Welding Society Services / Technical Standards & Publications / Change in welding current polarity

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