Saturday, April 2, 2016

On Salvaging Old Gear

On the face of it, salvaging old gear of any kind seems like a paying proposition. Retail prices of anything new these days are sky high, and are unlikely to ever come down. But are there really savings to be had in salvage?

Much as I'd like there to be, and much as this blog has often featured salvage projects as subject matter, I'm not so sure that salvage effort is always, or even often, worthwhile.

Over my years of servicing laser and impact printers, and working closely with printer subassembly remanufacturing operations, it dawned on me that there seems to be nothing quite like factory 'newness'. No matter how meticulously an old mechanism is refurbished, its service life and reliability are unlikely to equal those of new replacements.

Anyway, for want of anything better to do, I thought I'd refurbish an old water supply shut-off valve, and test it out to see if it could still be trusted to give leak-free service. Here's a view of the valve.

It's a common 1/2" copper pipe to 3/8" compression fitting shut-off valve, as is typically installed for a faucet's water supply. This one appears to have been installed by a DIYer -- there's evidence of some sort of sealant having been applied to places where there ought to be no need for sealant. DIYers are notorious for gratuitous application of sealant.

I'll clean it up nicely, and devise a test fixture. If it doesn't leak at its valve stem when fully opened, I'll consider my refurbishment to have been a success.

Following are a few noteworthy points:


The washer in this type of valve is not replaceable. Water supply shut-off valves are so seldom closed that washer wear is not an issue. An embrittled, cracked washer would spell the end of a valve's usefulness, unless one wanted to undertake the machining necessary to make the washer replaceable.

The Valve Seat

Like the washer, the valve seat is not replaceable. A corroded valve seat (unlikely) might be salvageable by reaming and/or burnishing with valve-grinding compound. See this post.

Valve Stem

The valve stem ought to be cleaned with fine steel wool prior to removal of the gland nut and seal. One wants nothing to abrade the lip of the valve stem's seal as the seal is removed.

The 1/2" Copper Pipe Socket

I've been meaning to acquire a 5/8" reamer to help me salvage 1/2" copper pipe fittings, but the price has been scaring me off. Meanwhile, I've been making do with an X-Acto knife and steel wool.

The socket must be clean, and must easily accept a pipe end to the full depth of the socket.

The Valve Stem Seal

There are two parts to the seal -- a thrust washer, and the ring-seal itself.

The thrust washer is concave; the concave side goes outboard. The ring-seal is asymmetrical face-to-face; note its orientation as you remove it.

The ring-seal must be resilient and undamaged, else the valve is a write-off. The seal pictured here looks a bit distorted on one side; it remains to be seen whether that will be detrimental.

Note the discolouration of the valve stem near the stem's thread. That's evidence of slight corrosion that may cause stem sealing to be iffy.

The Test

I assembled the cleaned up valve, using silicone grease on the valve's threads, and all its stem-sealing surfaces. I rigged a test fixture that allows me to install the valve onto a faucet that has a 3/4" hose-fitting thread on it. Here's a view of the valve in 'operation'.

The photo shows the valve pressurized and fully opened. The valve's output end is closed, as it would be if it were supplying a closed faucet.

It looks good. There's not a hint of weeping at the valve stem.

So, that turned out well. It would be safe to put that valve in operation in an actual faucet installation.

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