[TheForge] report on one small compressed air portable tank experience

[The Wilson's]

Jeff V

I made a portable air tank several years ago by brazing a Schrader valve
onto a 20 lb freon tank and adding a HP hose and QD fitting.  It has
worked OK for the few times that I have used it. 

HOWEVER!!!!!!!!

   Last week the engineers at work decided to do the same with a
disposable helium tank used for filling party balloons.  They got
curious as to the why of the OFFICIAL markings/ratings and WARNINGS on
the tank. So they looked it up in the spec sheets and DOT regs. Twenty
years later the ratings are still the same.  Here is the short version
of their research.  The DO NOT REFILL(disposable) tanks HAVE NOT BEEN
HEAT TREATED after welding. The refillable tanks, like propane, have
been heat treated/stress relieved after manufacture.   You might
reconsider using a tank that has been welded without stress relief heat
treatment. The pressurization / depressurization cycle may cause metal
fatigue and catastrophic failure. My EOD buddy calls the effect a
DANGEROUS EVENT.   He tends to understate his case sometimes.

I love to recycle. I'm a bit cheep sometimes.  I like to make my own
tools.   I think I'll buy a purpose built air bubble next time I'm in
town and use the freon tank for a forge shell.

Your results may vary.

Jeff Wilson
Wilson and Son Blacksmithing
Visit WWW.fortnisqually.org