From: Robert Bastow <"teenut"@ hotmail.com>
Subject: Re: Moving gas cylinders.
Date: Fri, 23 Jun 2000 03:24:24 GMT
Mike Graham wrote:
(Snip good advice on moving, chaining, gas cylinders)
> You don't really have to worry about the cylinder going 'pop'... it won't.
> You could drop it from a moving freight train and it would survive intact.
Ain't that the truth!
Few people realise how "high tech" and TOUGH a High Pressure gas cylinder is.
Even in North America..(Which has the LOWEST Spec, LOWEST pressure and HEAVIEST
cylinders in the world!!)
A Modern gas cylinder to US DOT spec has a minimum wall cylinder thickness of
(IIRC) 0.215" and is forged (in larger sizes) from a solid billet of 4130X
steel..the X indicating that it is a special "Tighter, Cleaner" spec than
regular 4130 steel (Incidentally, most US Steel Producers CAN'T MEET this
spec!!! We had to ship steel in from Brazil and Mexico to make cylinders to the
(worlds lowest) US spec
The solid forged shell is then spun or forged to form the neck..which is welded
solid during the process (or should be!!! Whole different story for another
It is then heat treated..oil quenched and tempered..before the neck threads are
machined, the collar swaged on, stamped with serial numbers etc, pressure tested
and shipped to the customer.
The resultant cylinder has ABOUT the tensile strength, etc., of a good quality
mechanics wrench! Hit one with a sledge hammer and it will BOUNCE RIGHT OFF
IT!! If you EVER see a dented cylinder RUN don't walk to the nearest exit...it
takes a HELLUVA whack to dent a cylinder!!
The two main enemies of HP Cylinders are Arc Strikes and corrosion. An arc
strike on a cylinder will draw the temper and is grounds for INSTANT
CONDEMNATION. Corrosion is a fact of life..and one of the reasons for scheduled
inspection and Hydro testing. So long as the corrosion is even and NOWHERE does
the wall thickness fall below minimum,(as measured ultra-sonically) then the
cylinder, provided it passes Hydro testing (HydRAULIC Mike and other
Canucks..NOT Hydro ELECTRIC)..will soldier on indefinitely. There are cylinders
of pre-war (FIRST WW) vintage still in good service here in the US.
However, LINE corrosion..as in lines of pits, usually found in a ring around the
inside of the base, is grounds for condemnation!
More than you EVER wanted to know. Huh!