Electropolishing

[rydia]

Has anyone had any experience with electropolishing AL-6XN piping? I have a flow diagram that indicates a certain portion of AL-6XN piping to be electropolished. Seeing as how AL-6XN is already a high quality alloy, are there benefits for it to be electropolished?

Also, what would generally be the sequence of events for electropolishing? Would piping materials be pre-polished, then the spools fabricated, and then the spools polished again to account for the welds? Or, would the same quality be met if the spool was only electropolished after fabrication?

Any feedback would be much appreciated! Thanks

 

[EdStainless]

Yes, it is electropolished.
In general, it does not look like 316 when EPed. It has less lusture and more variation in appearence.

IF you can prove that the EP surface cleans better or some similar reason then I can see doing it. EP of AL-6XN has no practical impact on the corrosion resistance of the material.

Typically the tubing and fittings are EPed and then welded. The welds are left as-welded. Often they use Ni alloy weld rings or filler metal to improve the corrosion resistance fo the welds.
There is usually a mechnical polish prior to the EP, but that is more driven by convention. People that think that low Ra values actually mean something drive this.
The welds are a very small fraction of the system. If you were making fittings or small spools you might consider welding, annealing, mech pol, EP as a production seq. Then you could use autogenious welds.

I would be more than glad to discuss polishing, EP, and the role in a system with you in detail.

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