Thread: another one for Grahame about acetylene

Originally Posted by durwood

it is a No No to put acetylene gas in contact with copper. It seemingly forms "copper acetylide". which is highly explosive - never heard of it before.
Correct its is HIGHLY EXPLOSIVE

As brass contains copper and a lot of welding tips are copper if there was any danger of explosion as is being suggested wouldn't putting acetylene through a copper tip and then adding oxygen produce an even greater hazzard?
No ,cos nozzles are not copper ,its an alloy-CIG assured me it was all safe years ago
Seems that I've seen lots of welding manifolds made up with copper piping or am I mistaken?
Yes,you need to talk to a gas fitter as to why?

Be afraid,very afraid instead, of oil/grease getting into high pressure side of regulator fitting into the cylinder neck.

Theres a few every year that qualify for the Darwin Award through this medium.
It's basically the same principle as a diesel engine except there's no cylinder and piston to contain the explosion.

I know of no fatalities of copper acetylide explosion but regrettably I do have knowledge of the other.
The moral of the story is keep your fresh uncapped cylinder away from oil or grease.IF hands are greasy or oily wash them before changing out cylinder.

Grahame

The safety cut of point for Cu in alloys in contact with acetylene is 70%, as long as the allow has less than 70% Cu its OK, standard Cu water pipe is definitely a no-no!

I had heard about if oil gets in your regulator it explodes----thought it was the oxygen that explodes,but never knew 4 sure . ?
I havent bought acetylene in years ---just use LPG for cutting and brassing.So if its the acetylene and not the oxygen that explodes when in contact with oil,then cutting /brassing etc with LPG and oxygen would not pose that risk? Be good 2 know 4 sure .

Its definitely oxygen in contact with oil... oxygen+carbon not good.

"Be afraid,very afraid instead, of oil/grease getting into high pressure side of regulator fitting into the cylinder neck."

Sorry boys,
It should have read

Be afraid,very afraid instead, of oil/grease getting into high pressure side of oxygen regulator fitting into the cylinder neck.


My apologies for the misunderstanding.
I was trying to put across the point that there is statistically more chance of being blown up this way than by an a copper acetylide explosion.

Oxy acetylene plumbing is definitely not a DIY area.

My bad.

Grahame

While a bit OT, from airforce days, pilots with a waxed moustache and using an oxygen mask were not a good combination, could end up with badly burnt face.

Not quite what the thread is about and I have written about this in other posts, but I got around the acetylene issue as a casual user by using LPG in place of acetylene for my flame-based metal work.

This means I save on the annual rental of the acetylene cylinder as I need only the oxygen bottle and I never run out of gas as access to PG is ubiquitous and it is cheap and easy to have spare bottle on standby (for BBQ or welding/ cutting).

Oxy/LPG is much safer than oxy/acetylene with little loss of performance for the hobby user or even the commercial, but occasional user. I have a CIG Comet 3 set with regulators, handpieces, hoses & tips that I used for years with Acetylene then converted to LPG. Same regulators/guages, same swaged tips and handpieces. I had to get an adapter to connect the hoses to an LPG bottle and a new LPG tip for my cutting handpiece. That was it - all up about $60 - saved on the first bottle of LPG I used instead of acetylene.

Sure the heat output is reduced, but for most applications this is not an issue - for heating simply I use a larger tip size as necessary or just a stronger flame. For brazing copper and brass and work on various alloys the cooler flame is mostly an advantage, especially for the irregular user.

I have cut large RSJs up 10 300mm x 150mm and mild plate up to 30mm with no problems albeit slightly slower than with acetylene, but I'm talking minutes here not big differences. Mainly just a bit longer to get the metal to the right temp to start the oxy cutting stream then the speed is little different.

On thinner plate this is almost unnoticeable. Using oxy/LPG to cut plate under 4mm can reduce distortion as the flame is cooler although this is not usually a big problem.

The oxy/LPG flames are easier to control and adjust in my experience and there is no flashback threat (although i have used safety arrestors on my hoses for many years anyway and reckon they are cheap insurance).

So - for cost, convenience and safety I reckon occasional non-professional users should go to oxy/LPG. And there is no problem going back to acetylene if need be in future.

Originally Posted by Bloss

I have a CIG Comet 3 set with regulators, handpieces, hoses & tips that I used for years with Acetylene then converted to LPG. Same regulators/guages, same swaged tips and handpieces. I had to get an adapter to connect the hoses to an LPG bottle and a new LPG tip for my cutting handpiece.

LPG fuels gas limits one to oxy cutting ,brazing and silver soldering tasks. If you need to weld with it, LPG is not hot enough to melt steel.As far as heating it does a lousy job on thicker work sections.

Its not all about saving a dollar.

Grahame

As I said "for cost, convenience and safety" not just or "all about saving a dollar". In my experience few home users would be wanting to gas weld steel as stick welders and MIG units are very accessible and inexpensive nowadays and the rods and fluxes etc make the jobs easier than in the past.

The original question seemed from a novice and home user. As always, horses for courses - there are some jobs that you have to use gas for and some not.

My observations were as a long time user of both LPG, acetylene, stick and MIG and my preference for most jobs where gas is indicated as the best tool (for the reasons I gave) is to just stick with the LPG.

Those reasons are valid - if they don't match your needs then use acetylene or whatever does - guess what, it's your choice . . .

BTW - In terms of knowledge and expertise in welding Grahame is a great resource to this forum - his posts to help members generally as well as replies to questions on all manner of welding subjects are superb.

But . . . a good many of us are irregular and casual users of various technologies and techniques and for professionals who have internalised so many of their skills and much knowledge, understanding the needs of the amateur is not always easy.

Grahame's posts are accessible to most of us at all levels - an unusual and valuable skill.