Pinhole Remedy After Welding Sheetmetal Patches?

72bluNblu said
Exactly. All kinds of stuff is welded that has to be air tight, fuel tight, even pressurized at high pressure,. Fuel tanks, propane tanks, oil pipelines, etc, it's a long list. Pin holes are not inevitable.



That's exactly the point. It doesn't react with the metal. It literally will not mix. And if (and WHEN) it leaks, moisture gets behind the repair and it rusts out. The metal on these cars flexes, the resin will separate, and the repair will fail.
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I'll agree that pinholes are not inevitable, but to be fair, most thin gage applications are pinch roller welded or some other methods.

And I would never advise using fiberglass to fill a pinhole.

If you're getting lots of pinholes, try adjusting your gas postflow to flow gas a little longer after the weld, and keep your torch on the weld until the gas shuts off.