Craftsman 313.54403 Oxygen Regulator Leak and Fix

 I bought a Sears Craftsman oxy-acetylene welding kit back in the 1970s. For the most part it's worked fine over the years but maybe 15 or 20 years ago the oxygen regulator began leaking such that the low pressure side would slowly creep up in pressure from the set point if the oxygen wasn't being used. A couple of days ago I decided to search the net to see if I could find a rebuild kit for the regulator. In the process I found a site where someone showed where he'd taken the sealing part out of his regulator and sanded it down to make it work again. Kind of. He said that the pressure still slowly crept up, 5 psi in 15 minutes, but that it was better than before, although he didn't say how quickly the creep was prior to the fix.

My regulator did a lot of creeping prior to me fixing it. The gauge went from 25 psi to 45 psi in 1 minute. Whoa. I knew of the issue so I just had to keep an eye on it when I was using it, and had to turn off the oxygen supply if I had to let the thing sit for any length of time. That got to be a pain. Time to take action.

The photo above shows the regulator set to 25 psi. The photo below was taken 1 minute later, and the needle is showing almost 45 psi (!). Yep, not a pretty sight.

This next photo shows the seat and associated parts.

That seat has seen better days. I think the black material is a hard rubber compound. I had taken the regulator apart a couple times in the past hoping I could just clean up the seat and get it working again, but alas, it still leaked. A simple cleaning didn't cut the mustard.

Desperate times call for desperate measures. Out came the 220-grit sandpaper. It took maybe 5 minutes to sand down the rubber/brass to one flat plane.

I then used 400-grit sandpaper to get it smoother.

I probably didn't need to do this last step but I then used this sharpening stone to try and smooth it out even more. Not sure it made a difference.

Ok, this next photo shows 25 psi again...

... and after a 5 minute hold, no discernable creep. Yay!

The model number of the regulator begins with "313", indicating that the regulator was made by Harris Calorific according to VintageMachinery.org's lookup table of OEM vendors for Sears. I did find a rebuild kit online for a Harris Model 25 regulator, and the rubber seal looks very similar to mine, however I just don't know if the parts are compatible. If my regulator ever leaks again, I might just spring for the $25 Harris rebuild kit next time and hope the parts fit.