Metalworking (rec.crafts.metalworking) Discuss various aspects of working with metal, such as machining, welding, metal joining, screwing, casting, hardening/tempering, blacksmithing/forging, spinning and hammer work, sheet metal work.

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Old February 20th 08, 12:55 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

I have a gate valve with a small leak I need to fix. The valve is
stainless and in good condition but has a very small leak when closed
tightly. It's a 3" valve with a non-standard flange so replacement is
out of the question. The valve will be seldom operated and I could live
with a fix that sealed the valve tight and allowed the valve to be
opened ONCE (for a fire hose connection).

The big complication is that the valve is welded together and cannot be
taken apart.

I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/

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Old February 20th 08, 04:35 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

nick hull wrote:

I have a gate valve with a small leak I need to fix. The valve is
stainless and in good condition but has a very small leak when closed
tightly. It's a 3" valve with a non-standard flange so replacement is
out of the question. The valve will be seldom operated and I could live
with a fix that sealed the valve tight and allowed the valve to be
opened ONCE (for a fire hose connection).

The big complication is that the valve is welded together and cannot be
taken apart.

I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/



If you have the valve out of the system, and apparently you do, open the
gate fully and check the seat under the gate for corrosion or dirt that
keeps the gate from going completely closed. That may eliminate the
problem. If that's not it perhaps placing a thin bead of silicone under
the gate and allowing it to cure before closing the gate will solve the
problem.

Jim
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Old February 20th 08, 04:36 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

On Feb 20, 7:55 am, nick hull wrote:
I have a gate valve with a small leak I need to fix. The valve is
stainless and in good condition but has a very small leak when closed
tightly. It's a 3" valve with a non-standard flange so replacement is
out of the question. The valve will be seldom operated and I could live
with a fix that sealed the valve tight and allowed the valve to be
opened ONCE (for a fire hose connection).

The big complication is that the valve is welded together and cannot be
taken apart.

I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/


I don't have lots of experience, but every gate valve I have seen (5
or 6 of them) leaked some when closed. I think that the silicone
sound like a good idea, but I would think that the downstream side
would be better since any (even your low) water pressure would force
the gate into the silicone rather than away from it.

Carl Boyd
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Old February 20th 08, 04:54 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

nick hull wrote:

I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.


Jim Chandler wrote:

If you have the valve out of the system, and apparently you do, open the
gate fully and check the seat under the gate for corrosion or dirt that
keeps the gate from going completely closed. That may eliminate the
problem. If that's not it perhaps placing a thin bead of silicone under
the gate and allowing it to cure before closing the gate will solve the



Rather than RTV silicone (caulk), I'd suggest either silicone grease (I
prefer the high-vacuum type - it's pure and pretty stiff - some of the
automotive variety I've met is thinner) or beeswax (buy a toilet seal
ring) on the sealing surface.

--
Cats, coffee, chocolate...vices to live by
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Old February 20th 08, 06:01 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

On Feb 20, 11:54 am, Ecnerwal
wrote:
nick hull wrote:
I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.

Jim Chandler wrote:
If you have the valve out of the system, and apparently you do, open the
gate fully and check the seat under the gate for corrosion or dirt that
keeps the gate from going completely closed. That may eliminate the
problem. If that's not it perhaps placing a thin bead of silicone under
the gate and allowing it to cure before closing the gate will solve the


Rather than RTV silicone (caulk), I'd suggest either silicone grease (I
prefer the high-vacuum type - it's pure and pretty stiff - some of the
automotive variety I've met is thinner) or beeswax (buy a toilet seal
ring) on the sealing surface.

--
Cats, coffee, chocolate...vices to live by


Can you machine a small o-ring groove in the down stream face of the
valve disk an glue in a small o-ring? This would be a permanent
fix.

Wolfgang


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Old February 20th 08, 08:00 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

nick hull wrote:
I have a gate valve with a small leak I need to fix.


After removing the gate assembly, you will probably see crud trapped in the valve seat.
Remove crud and clean innards, lubricate with silicone grease and reassemble.

....Would be my advice.

--Winston
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Old February 20th 08, 09:10 PM posted to rec.crafts.metalworking
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Default Leaky valve problem

You could put a cap on the output pipe. With a couple of nice handles
for easy & fast removal. Bob
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Old February 21st 08, 12:19 AM posted to rec.crafts.metalworking
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Default Leaky valve problem

nick hull wrote:
In article ,
Bob Engelhardt wrote:

You could put a cap on the output pipe. With a couple of nice handles
for easy & fast removal. Bob


I'll probably do that in any case. The cap will cost $44 (2,5"
firehose) ;(

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/


Nick, If it's going to feed a pump or a nozzle make sure that anything
you put on it cannot come off easily. Loose crud doesn't help a nozzle.
We use a silicon grease on the valves on our rigs. Shame you aren't
closer we have a LOT of spare 2.5" stuff around the station.

That price for an NST thread cap is WAY high. We buy them for about 10
bucks for the lightweight aluminum and 22 for brass. Check with a local
station or service shop.

--
Steve W.
Near Cooperstown, New York
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Old February 21st 08, 12:36 AM posted to rec.crafts.metalworking
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Default Leaky valve problem

In article
,
wrote:

On Feb 20, 11:54 am, Ecnerwal
wrote:
nick hull wrote:
I was thinking of putting a thin sheet of plastic on the gate, but if it
washed off when opened it might jam something. Maybe just a thin bead
of silicone on the upstream side? It's a water gravity system with only
5' of water head so pressure is extremely low.

Jim Chandler wrote:
If you have the valve out of the system, and apparently you do, open the
gate fully and check the seat under the gate for corrosion or dirt that
keeps the gate from going completely closed. That may eliminate the
problem. If that's not it perhaps placing a thin bead of silicone under
the gate and allowing it to cure before closing the gate will solve the


Rather than RTV silicone (caulk), I'd suggest either silicone grease (I
prefer the high-vacuum type - it's pure and pretty stiff - some of the
automotive variety I've met is thinner) or beeswax (buy a toilet seal
ring) on the sealing surface.

--
Cats, coffee, chocolate...vices to live by


Can you machine a small o-ring groove in the down stream face of the
valve disk an glue in a small o-ring? This would be a permanent
fix.


No, I cannot remove the valve disk. The valve body is welded and I
cannot access the top half of the disk in any way.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/
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Old February 21st 08, 12:39 AM posted to rec.crafts.metalworking
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Default Leaky valve problem

In article jF%uj.7161$0%[email protected],
Winston wrote:

nick hull wrote:
I have a gate valve with a small leak I need to fix.


After removing the gate assembly, you will probably see crud trapped in the
valve seat.
Remove crud and clean innards, lubricate with silicone grease and reassemble.

...Would be my advice.

--Winston


I cannot see or feel any crud. I can feel most of the seat, except the
top where the disk is in the way even when fully open.

Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/


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