Cutting torch "pop" - Next Generation

topic posted Fri, October 30, 2009 - 4:09 PM by  Tanemon
Okay... BIG THANKS to all DIY posters who kindly responded to my first query about my cutting torch popping (and sometimes blowing out) the pre-heat flame). You'll find my revised question, with the new info, by scrolling down a ways...

Among the carefully thought -out replies to my first question on the popping, was this very thorough one from Briggi:

"Going by the numbers, the industry satandard is about 4# at the O2 for welding thin sheet, on up to 20# for welding 4" slab. The fuel pressure is a function of O2 pressure, but roughly 3# up to 18# on the same scale.
For cutting it's about 5# for sheet on up to 60# for 12" slab.

In every case you'll want to achieve a hard light blue inner flame as big as the work requires. Having decided how big a head is required to make that size of flame, adjust pressure accordingly in order to maintain it. And that's where the art comes in. There are so many variables entering the picture that it's easier to make the flame you know you'll want instead of working it out first with a pencil.

A good excercise is to take any size orfice welding head at random, then, once having set the pressures at the regulators, and using the torch adjustments, see
a) how small a flame you can maintain, without sputtering & popping, and then...
b) see how large a flame you can make all with that same head.
You'll find that you can likely get most of your welding done, fine or large, using only one medium sized head, simply by fiddling with pressures at torch and regulator.
Even cutting is possible using that No.10 head simply by squirting in a bunch of O2 once you get your work melting yellow with your other hand at the torch valve knob."

Excellent. But now I figured out a very useful bit of info: My torch is popping in the pre-heat flame only phase with the Victor #2 cutting tip, but NOT with a Victor #1 (smaller) one.

Both the #1 and the #2 appear to be in good shape. The #1 poses no problem. The #2 is actually a few years newer than the #1, but the #2 is actually only a few months old, and shows no dents or nicks, even under magnification.

My acetylene tank is probably about 40% full right now, but still delivers the proper pressure according to the regulator gauge: setting reg pressure at 5-6 psi (with, of course, the torch valve fairly open while setting). The gas in the O2 tank is almost full up, at present.

Does this info shed any light on the popping habit of the larger (but still quite medium-sized) tip?
posted by:
  • Re: Cutting torch "pop" - Next Generation

    Sat, October 31, 2009 - 8:38 AM
    Again, you have to check the tip seal. Just because you don't " see" any thing wrong, doesn't mean it is seating properly. If you have access to automotive valve lapping compound, ( a gritty paste ) use it on the bevel of the seal. If not you can make a paste of Ajax cleaner. put it on the seat and rotate while pressing down for a minet or two. The surfaces of both the tip and body should be a perfectly even sheen, or gloss. If not have a seal problem. Miner problems can be repaired with the lapping compound, spin for abt 5 min. making sure to keep compound on the seal.
    • Re: Cutting torch "pop" - Next Generation

      Mon, November 2, 2009 - 10:41 AM
      Backfire and flashback caused by improper operating pressures can blow back soot, particles, dust, clear to the regulators. Clean this soot out.

      Check for gas leaks at all joins, both before and during opening of large O2 valve handle on cut torch. Telltale bubbling says "leak", when you put spit, or soap water on joins. Better yet, dunk the torch in a tub of water once pressures are set, to look for bubbles.

      If there proves to be leaking compromising pressures, then look to repack seals, change out O-rings, or as previous post, doing the necessary to get sealing at your blowpipes, torches, cutting rigs.

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