pulsed mig porosity caused by dye penatrant

Date 11-02-2013 13:39

Rgunn,

WELCOME TO THE AWS WELDING FORUM!!

GMAW is sensitive to many various contaminants and will yield porosity if not carefully prepared for welding.

Dye pen, especially if a flaw was deep enough to have trapped very much of the fluids, is one such contaminant. It will need to be carefully cleaned after testing and possibly even ground out slightly to get to the deeper levels. This only makes sense to me as you need to grind into the original weld or material where the discontinuity was found anyway in order to repair it. Otherwise you are only covering it up and that is not a correct repair.

I would ask though, what specification electrode are you using? Shielding gas composition?

What parameters are you welding to? Volts/amps (wire feed speed)? Pulsing frequency?

What code is involved?

What material are you dealing with?

This will help in giving you more accurate information for correcting the problem.

Have a Great Day, Brent

By 803056

Date 11-02-2013 18:42

I will go a step further than Brent and say the entire discontinuity has to be excavated if you have any hope of rewelding the affected area with no porosity.

All dye penetrants are petroleum based, i.e., oil based, material with concentrated dye stuffs (yes, that is the technical term). As such, any remaining petroleum product will produce porosity. The amount of porosity is largely dependent on the volume of penetrant remaining in the unexcavated discontinuity.

Whether the porosity present is accepted or not is dependent on the welding standard that governs fabrication.

Some materials, i.e., aluminum alloys, will produce more than others, but there will be porosity present, either or both surface breaking or subsurface.

Best regards - Al