[Braehill]

Acetylene forms explosive compounds with copper, brass, copper salts, mercury/mercury salts, silver/silver salts and nitric acid. Under no circumstances should acetylene gas come in contact with unalloyed copper, except in a torch. Any contact of acetylene with high-alloyed copper piping will generate copper acetylide, which is very reactive and may result in a violent explosion. Also, an explosion hazard will result if the gas comes into contact with silver bearing materials such as those used in silver-brazed pipeline joints.

The upper limit for Copper content in brass is 66% if I remember right. I've been told that because it only passes through a torch and then it's burned up that it has very little time to decompose with the Copper and Silver in the torch. Most torch bases up to the mixing valves are made of yellow brass and are not Silver soldered before that point, thus keeping this reaction local to the business end of the torch.

Len

[noddybrian]

I'm probably wrong & it's so long ago I don't know who told me - but I thought all these reactions / potential to spontaneous explode happened only over a certain pressure -so the reason you can't get a higher pressure regulator is to prevent anyone using too high a pressure by accident - it's why we had to use an alternate gas when cutting underwater ( except very shallow / just under the surface stuff on pilings etc ) are you saying this can happen in the normal use range ( around 5psi ) ?

[Braehill]

Brian,
I'll refrain from answering that because I don't know the actual pressures and temperatures that it's possible. Most of what I posted is from the Mine Safety Addmins. Litature.

When I get a chance I'll look for a safety gram with more info at work.

Len


Sent from my iPhone using Tapatalk

[Braehill]

Brian,

Here is the safetygram off of Air Products web page for Acetylene.

http://www.airproducts.com/~/media/File ... ram-13.pdf

Len

[Superiorwelding]

Len,
Very informative! I have not read the whole thing, but already I have learned a lot. Thanks for putting that info up for us.
-Jonathan

[noddybrian]

Len

Thanks for the reply - I'll read through that properly when I get a chance.

[Otto Nobedder]

Thanks, Len,

That clears up the copper/brass issue I was concerned about.

Unalloyed (near pure) copper is a big no-no, and 70-30 brass alloys don't like "wet" acetylene.

Based on that, I would still not use any copper (alloy or not) or red brass in a central distribution system.

Yellow brass, like our cutting torches, are highly alloyed copper, thus safe up to the 15 PSIG. Seems a narrow margin, though, as the article I cited said decomposition can occur at 29 PSIA, and a "standard atmosphere" is 14.7 PSIA, making 15 PSIG equal to 29.7 PSIA.

There must be a "safety factor" built into that 15 PSIG number, since so few Chinese gauges are accurate within a 2-PSIG margin...

Steve S

[braderfitter]

we use unitor equipment onboard and the central distribution pipes are all stainless still so I'm not worried and besides the ships is already 10 years old . but i have to admit reading so much information sometimes scares me even though i am in this job for 20 years

[braderfitter]

I think I have to recalibrate my brain from metric to English unit because I have to pause for a while to convert every number but I will get along I just need little time. i find all information here as very helpful kudos to everybody

[weldin mike 27]

Hey,

This answers why the acetylene pipes at out trade school were all stainless. That is a fact i had forgotten.

[Otto Nobedder]

LOL, Ariel,

I'm used to using the metric system in so many things, but I still havn't made the adjustment from PSI to KPa...

Steve S

[Superiorwelding]

I have witnessed a few welders just throw their oxy/acetylene tanks in the back if their trucks. If only they watched this video first, maybe they would think twice.
https://www.youtube.com/watch?v=FG1LGKieTxY
-Jonathan

[noddybrian]

It's safer in England - the price Calor charge for propane you'd never afford a truck full ! - looked bad though - had to check it was'nt a clip from a " Final Destination " film !