Re: Gas Shutoff Valve--- a tedious job

Posted by carla on July 27, 1998 at 16:42:33

In Reply to: Gas Shutoff Valve
posted by Jim Miller on July 27, 1998 at 09:54:48

hello, jim,
i think you might be able to recon the valve in situ, which, i think, would be preferable to risking tank damage.
after removing the valve handle and packing nut, try to remove the steel or brass washer above the packing. it may not come loose easily, so it may be necessary to grind a centre punch for clearance to mark the exact centre of the washer. good light is essential.
then drill (using a hand drill) through the washer with a very small drill, taking care to be on centre, and to stop immediately you've gone through, so as not to risk scarring any internal surfaces with the drill.---continue with slightly larger drills until the washer is almost split.
use a packing hook improvised from an icepick with a bent tip to remove the washer and the packing.
observe whether the mating tapers of the valve body and the plug are damaged----a bit of sharp dirt from the tank may have scored the parts beyond repair.
if they're not badly scored, use some fine valve grinding compound to lap the parts until they fit and seal well.
clean the valve well, and fit new packing--use a little bit of light grease on the packing.----tighten the gland nut only enough to keep from leaking.
if the valve is not usable---write off the valve to be certain of saving the tank.
saw off the valve as close to the tank as might be without scarring the tank, then, using a small round (rat-tail) file, file out the hole in the shank of the valve into a slot-- this will require a good light, and a good bit of patience.
using a small mirror if needed, file and look, file and look, until you see barely visible lines which tell you that you are just beginning to file into the threads.
once the part is filed out to the threads, it will have no strength, and can be easily removed with an easy-out.
the job is worth buying a new, best quality file, as a file which has been used on steel will, often, just "skate" on a brass part.
use great care and patience to be very certain you don't go too far, and damage the threads in the tank. be certain to use a proper file handle on the file.
hope this helps
carla
p. s. drilling out the bore of the valve where it fits the tank will save time spent filing--if you do---be very careful to have the drill aligned correctly so you don't risk striking the tank threads.---and---use a hand drill---never use an electric drill motor near an empty fuel tank cos the brushes will spark, and the fuel vapour might possibly explode--- not too likely, maybe, but the little bit of time saved is not worth taking chances.---this also applies to using an air drill--it can't spark, but the chip might be a little warm.

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