American Welding Society Forum
I'm am currently working on a job where the contractor wants to use ER316LFC GTAW rod to weld stainless pipe without an internal purge. This is a flux covered GTAW stainless rod, but I'm unfamiliar with the "FC" designation. What does it stand for? and what problems can I expect to have with it?
A lot depends on the intended application and the presumed working enviornment of the root bead's wetted surface. Several years before I retired from a large chemical company we ran corrosion tests (submersion, etc.) on a similar electrode. We found that we could satisafactorly put in an open root but noticed the slag was quite tenacious on both root faces. The real problem arose with the "wetted" root face, specificly at the toes of the root bead (HAZ). The slag was so tenacious at the edges (a very thin line) that our metalurgist after his testing had been completed, declared the electrode "unfit for corrosive fluid service" and for control purposes, we disallowed the electrode's use for any of our work.
That thin line of slag promoted and supported an enviornment for corrosion attack and if the electrode were to be used for the fabrication of piping systems, the internal root beads would be reasonably inaccessable to ensure/facilate complete removal of the slag prior to service.
If it's a piping system your contractor is to fabricate, then I've heard his argument many times. He's concerned with time of purging and cost of gas and not concerned with what he is leaving for you to contend with after he's gone. Which is your plant having an unscheduled shutdown because a weld fails from corrosion caused cracking or pinholing even though his welds met the minimum requirements of the spec- hes not responsible but he caused it!
Some sage advise- Beware, do some testing or gather testing data before making your decision.
Thankyou for your advice and the information. We are already leaning heavily toward not allowing it. We had not yet considered the corrosion aspect, but on the trial welds they have made there is definitely slag on the internal face of the root and pipe. I would very much like to see your metalurgist's report if possible, if not thanks for the info and we will run further tests here.
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