Oxy/Acetylene question

[jaybee]

I'm having a lot of fun but it won't last if I can't get more consistent rusults.  At this point most of my work is looking pretty good--smooth, deep, and I can pound it half to death without moving the pieces, let alone breaking the weld.  I'm getting unpredictable quality, though.  Every so often I get a weld that's weak and full of carbon, but I don't know why.  Flames also flash out the opposite end of the pipe I'm working on occasionally and that doesn't seem right.  I'm setting up my flame with the second cone being just the same size or slightly longer than the center cone.  I'm also using what seems like a lot of Acetylene to get sufficient heat into the part.  Then again maybe I've been moving the puddle too slowly at times and I'm overheating the work area.  My latest work seemed to move considerably faster and yet it's very solid and looks great.

Help please, I think I'm getting myself lost!

[unklian]

What pressures are you running ?

[jaybee]

4psi on both regulators.

[Rex Schimmer]

Take your oxygen pressure up to around 10, 4-5 on the acetylene is good. Make sure that when you are adjusting the flame so that the inner cone is sharp, not fuzzy. If you are welding tubing and you get flame out of the end I'll bet that there is some risidual oil from making the tubing in the tube and this is flaming out the end. This could also be your problem with weld quality.  I am assuming that you are welding mild steel. Remember to make sure that there is no rust, oil or any type of smegma where you are welding or weld quality suffers.

If you can oxy- acetylene weld you can TIG, fact is it is easier! so save up your bucks and buy a TIG then you will have great welds.

Rex

[Fat Cat]

Take your oxygen pressure up to around 10, 4-5 on the acetylene is good.

That works fine in most cases but if you are using a Dillion/or Henrob torch. They will not work well with 10psi oxygen settings.

[jaybee]

Thanks for your advice.  Increased Oxy pressure does seem to help with the flame stability and heat output.

I reground the joint I was having the most trouble with and tried again.  For some reason I just can't get the puddle to fuse properly.  Most of the time if the puddle doesn't flow together right away from both sides a little dab of filler will get everything moving and I can just move the puddle along from there without too much trouble.  On this bit it's almost like the two sides of the weld are repelling each other, they seem to want to flow apart instead of together.  Even the filler wants to form a little ball on the end of the rod instead of dropping in.  Everything seems to be clean, dry, and shiny, but I'm guessing maybe some cutting oil or other contamination in the joint?  Maybe I should just throw away the piece I'm working with and start with a fresh one.

[enjenjo]

if this is exhaust pipe, it may be 704 stainless, which will rust, but is a bear to weld. A picture would help.

[jaybee]

Plain old iron pipe, 1 1/2"

[GPster]

Plain old iron pipe, 1 1/2"

If you're talking iron pipe like Schedual 40 gas pipe this is going to be about 2 - 3 Times as thick as exhaust pipe and the thinckness might be part of the reason it won't flow. GPster

[jaybee]

Yes, that's exactly what I'm using.

[C9]

If you have to gas weld the thick stuff, preheat it as best you can.

I've had success in butt welding 1/4" - to make an old time scatter shield taller so it wasn't real critical.

Preheated it orange to red hot and the metal flowed out well with a #5 tip.


If you're welding thin exhaust tubing, I like 4# on each regulator.
That's what my Henrob/Dillon recommended and it works well with that.

4# each regulator works well with my standard Marquette torch.

I believe it's Fournier's Metal Fabricating Handbook that recommends 4# on each regulator for most gas welding regardless of torch brand.
I'm guessing that he's doing thin stuff and the 10# oxy may be better for the thicker stuff.

One thing you may have to do is exchange the regulator line gauges for ones that read 30# maximum.
The line gauges are usually scaled too high to make reading low pressures easy.