[TheForge] repost of propane cylinder cutting

Mon Nov 25 11:45:59 2002

hello;

this posting covers standard cylinders used on
gas grills and rvs. 

scrap lift truck cylinders, roofer cylinders,
plumber cylinders are different cylinders
and need to be treat differently. i will cover
those in a separate post.

warning, note.

cutting scrap propane cylinders is dangerous,
there is no room for mistake here. generally
with a mistake here someone is either severely
burned or someone is killed. (this basically
applies to any type of scrap cylinder)

assuming you have a scrap propane cylinder this
is were is begin.

0. does this outdoors or in an extremely well
   ventilated building. i generally do this at
   night when the cylinder has had a chance to
   cool down. 

1. make sure that the cylinder is really empty.
   using a weed burner attached to the tank
   burn off any propane left in the cylinder.

   with the older type 1 values on cylinders
   this gives you reasonable assurance that
   the cylinder is in fact at 0 psig. this
   does not mean that the tank is empty of
   propane vapor. repeat this does not
   mean that the tank is empty of propane
   vapor.

   with the newer opd (overpressure protection
   device) values this gives you some indication
   that the tank should be at 0 psig but they
   may not be. these new opd values do fail
   and they can either fail in the open position
   or in the closed position. if it has failed
   in the open position tank pressure should be
   at 0 psig, if it has failed in the closed
   position tank pressure could be as much as
   125 psig.

2. time to attempt to remove the cylinder's
   valve. do *not*, repeat do *not* lay the
   cylinder down to remove the valve. if there
   is still any pressure in the tank when the
   value is removed the tank becomes a missle
   sliding across the ground. with the cylinder
   standing upright, secure the cylinder to a
   fixed support (tree, other cylinders, steel
   post in the ground, fence post, etc ) with
   either chain or a strap wrench-type hold down.
   turn off all radios, cd-players, tape players,
   etc you do not want an unnecessary noise.
   do *not*, repeat do *not* place your body
   anywhere over the valve. if there is any
   pressure in the tank when you begin to
   loosen the valve the risk of the valve being
   shot into your body is too high.
   using either an open end wrench or large
   adjustable wrench slowly loosen the value.
   listen for any "hissing" or "whistling".
   this indicates that there is still pressure
   in the tank. if you hear any "hissing" or
   "whistling" allow the tank to vent. go get
   coffee, tea, milk, etc. take a break.
   when the "hissing" or "whistling" has stopped
   loosen the value some more and keep listening
   for the "hissing" or "whistling".
   once you have the valve removed the situation
   is becomes somewhat safer.

3. using a water hose fill the tank through the
   value opening till it begins to over flow. add
   a couple drops of dish washing liquid to the
   water. this breaks the surface tension of the
   water and allows the water to reach more of
   the cracks and crevices inside the cylinder.
   let the cylinder sit for 48 hours to a 5 days
   with the water and dish washing liquid in it.
   propane cylinders absorp some of the ethyl
   mercaptan that is used to give propane an
   odor. they also absorp some propane. the
   water will cause some of this to come out
   of the cylinder walls. after the 48 hours to
   5 days, dump the water out. it will probably
   look pretty digusting.

4. fill the cylinder with just water this time.
   you want to fill it to with in an inch of where
   you want to cut the top off. the reason for this
   is that if there is still some propane and ethyl
   mercaptan in the cylinder walls. it will ignite.

5. using either a oxy-fuel torch, plasma torch,
   grinder, etc begin to carefully cut the top
   off. do *not*, repeat do *not*, place your body
   over the valve opening. if the residual propane
   ignites it is going to flame out of the valve
   opening. you can be burned. once the top is
   removed you can dump the water out.

6. cutting the bottom off is now a simple task.

rules to remember:

1. safety comes first.
2. see rule 1.
3. propane can either burn you, freeze you,
   or sufficate you.
4. keep extraneous background noise from
   radios, cd-players, tape players, etc
   to a minimum.
5. do *not*, repeat do *not* do this when
   your spouse is around. if they are anything
   like mine, they hate the smell of propane. ;-)
   ( women just have a better sense of smell
     then men do, i guess. )
6. do *not* do this if there clothes hanging out
   on the "solar" clother dryer (clothes line).
   ;-) you will be washing the clothes over
   again and again to get the mercaptian
   odor out of them.

-- 
Terry L. Ridder ><>