"stone" wrote in message
om...
I have a secondhand, homemade aircompressor that uses a small tank
with a platform welded to the tank for the motor and compressor.

Is it safe to weld to an air tank?

At first I thought this was crazy to do, but then I thought of
the very high pressure welded pipes on gas wells, and so forth.


So, is it safe if welded properly? And second, if it does have a bad weld
on it, will it just pop out the weld and then fiz off, or is it
and explosion hazzard?

It's a homemade small air compressor set at about a 100 psi.


Thanks

This is one of those cases where if you have to ask, you really shouldn't do
it.
Admittedly this is UK but similar rules probably apply in US. To weld a
pressure vessel the welder has to be coded. That means that he passes a
practical welding test every few years. where the results are X rayed. These
guys are GOOD welders. Despite this, every welded pressure vessel is
subjected to a hydraulic test well above normal working pressure before the
vessel is certified for use. This test applies if the vessel is repaired or
modified as well.
The problem with compressed air is that gasses are compressible. That means
that there is a huge amount of energy stored in the cylinder. If something
fails, that energy will be released. If the cylinder breaks, the shrapnel
will fly like a grenade.
In short, don't do it.

John