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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/ |
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 |
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 |
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 |
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 |
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 |
Leaky valve problem
You could put a cap on the output pipe. With a couple of nice handles
for easy & fast removal. Bob |
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 |
Leaky valve problem
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Leaky valve problem
In article jF%uj.7161$0%3.1998@trnddc06,
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/ |
Leaky valve problem
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/ |
Leaky valve problem
nick hull wrote:
Bob Engelhardt wrote: You could put a cap on the output pipe. ... I'll probably do that in any case. Well, that's all you'll need - it's only holding 2 1/2 psi (when the leak has filled behind it) and the valve will hold back all but the leak when you take the cap off. The cap will cost $44 (2,5" firehose) I know that you have a lathe! BG Bob |
Leaky valve problem
In article ,
Bob Engelhardt wrote: nick hull wrote: Bob Engelhardt wrote: You could put a cap on the output pipe. ... I'll probably do that in any case. Well, that's all you'll need - it's only holding 2 1/2 psi (when the leak has filled behind it) and the valve will hold back all but the leak when you take the cap off. The cap will cost $44 (2,5" firehose) I know that you have a lathe! BG Yes but the firehose thread is 7 tpi, not listed on my change gear charts ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ |
Leaky valve problem
On Wed, 20 Feb 2008 21:21:40 -0600, nick hull wrote:
In article , Bob Engelhardt wrote: nick hull wrote: Bob Engelhardt wrote: You could put a cap on the output pipe. ... I'll probably do that in any case. Well, that's all you'll need - it's only holding 2 1/2 psi (when the leak has filled behind it) and the valve will hold back all but the leak when you take the cap off. The cap will cost $44 (2,5" firehose) I know that you have a lathe! BG Yes but the firehose thread is 7 tpi, not listed on my change gear charts ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ On my lathe, I have to swap the stud gear from 24 tooth to 48. Then I get 4 - 7 instead of 8 - 14. Could you do similar somewhere in your gear train? Pete Keillor |
Leaky valve problem
On Feb 22, 8:18*am, nick hull wrote:
... My error, the thread I need is 7 1/2 tpi ;( Do you have a friend with a South Bend 10L? 7-1/2 is on the 70 speed gearbox. |
Leaky valve problem
In article ,
Pete Keillor wrote: On Wed, 20 Feb 2008 21:21:40 -0600, nick hull wrote: In article , Bob Engelhardt wrote: nick hull wrote: Bob Engelhardt wrote: You could put a cap on the output pipe. ... I'll probably do that in any case. Well, that's all you'll need - it's only holding 2 1/2 psi (when the leak has filled behind it) and the valve will hold back all but the leak when you take the cap off. The cap will cost $44 (2,5" firehose) I know that you have a lathe! BG Yes but the firehose thread is 7 tpi, not listed on my change gear charts ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ On my lathe, I have to swap the stud gear from 24 tooth to 48. Then I get 4 - 7 instead of 8 - 14. Could you do similar somewhere in your gear train? My error, the thread I need is 7 1/2 tpi ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ |
Leaky valve problem
In article
, Jim Wilkins wrote: On Feb 22, 8:18*am, nick hull wrote: ... My error, the thread I need is 7 1/2 tpi ;( Do you have a friend with a South Bend 10L? 7-1/2 is on the 70 speed gearbox. Unfortunately no ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ |
Leaky valve problem
On Fri, 22 Feb 2008 07:18:32 -0600, nick hull wrote:
In article , Pete Keillor wrote: On Wed, 20 Feb 2008 21:21:40 -0600, nick hull wrote: In article , Bob Engelhardt wrote: nick hull wrote: Bob Engelhardt wrote: You could put a cap on the output pipe. ... I'll probably do that in any case. Well, that's all you'll need - it's only holding 2 1/2 psi (when the leak has filled behind it) and the valve will hold back all but the leak when you take the cap off. The cap will cost $44 (2,5" firehose) I know that you have a lathe! BG Yes but the firehose thread is 7 tpi, not listed on my change gear charts ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ On my lathe, I have to swap the stud gear from 24 tooth to 48. Then I get 4 - 7 instead of 8 - 14. Could you do similar somewhere in your gear train? My error, the thread I need is 7 1/2 tpi ;( Free men own guns - www(dot)geocities(dot)com/CapitolHill/5357/ Nope, can't do that one, sorry. It jumps from 7 to 8, although it does 6-1/2 and 6-3/4. Now that's a goofy pitch. Pete Keillor |
Leaky valve problem
I was the Engineering Officer on two Coast Guard Cutters, Auxiliary
Chief on one, Main Prop Chief on another, and general engineer on my first. When a cutter is in drydock the skin valves and other important valves are routinely removed and tested (the inlet side of the valve is filled with water and a blank flange with an water fitting attached is bolted to the valve flange. A predetermined amount of pressure is added through the fitting (150% of the working pressure? I don't recall exactly)). A specified amount of leakage is allowed depending on the size and type of the valve, and the normal operating pressure of the system. The quantity allowed is in Chapter 505 of the Naval Ships Technical Manual (NSTM) titled Piping Systems. Small valves did not allow any leakage, whereas larger valves were allowed XX drops per minute. Some valves (again depending on the type) weren't allowed any leakge (ball valves?). I tried to find a copy of this chapter (505) of the NSTM online without any luck ,to give as a link. I'm sure there are specifications elsewhere in the civilian world. I did find two chapters that may be of interest to this group (at http://www.fas.org/man/dod-101/sys/ship/nstm/ .); Chapter 075 - Fasteners and Chapter 613 - Wire and Fiber Rope Rigging. One chapter I couldn't find was Chapter 078 - Seals that is VERY good reading. I wish now I had kept copies of some of these manuals when I retired as they are is very good and can be very pertinent to our hobby/job. Dave Young 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/ |
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