EM12K procedure 2

[REGRUMBLE]

We are fabricating a vessel from 1 1/4" SA516-70 and our Sub arc proceure uses a Lincoln EM12K electrode which our customer claims is not suitable for PWHT. They did not give a reason. Does anyone know why this electrode is not suitable or which type of sub arc wire would be more suitable. The procedure must meet the same tensile, elongation and impacts as the parent metal. I have contacted Lincoln about this and they are not very helpful.

 

[Guest102023]

Usually better to stay with a 'certified' combination if it gives the customer a headache. Unless you will be using many tens of thousands of pounds, the extra pennies per pound should not matter much.

Also, you will typically qualify a WPS using no thicker than 1.5". This might buy you 8" in production, but at 8" it will require longer PWHT, lowering the strength of the production work. If I put myself in the owner's place, I would be wary of borderline acceptable test results on PQRs and how valid they might be for a given design. Remember, they are representative of given heats of plate, wire, flux, a given welder, etc. (the weather?)

I have done a bit of SAW welding, and found the AWS wire/flux classification system a bit clumsy.

 

[jte]

Regarding the "have not failed" statements... Those of you making that statement - have you tracked the vessels or have you simply not been notified? More often than not (read 0.1%) when I'm dealing with some type of issue with a vessel we do not notify the original manufacturer. Even if it was a fab shop foul up.

I'm no welding expert so I'll stay out of that arena...

jt