leaking pressure relief valve

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wsmcycle
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leaking pressure relief valve

Post by wsmcycle » Thu Dec 17, 2015 9:28 pm

My pressure relief valve is leaking. Just a small amount but it's winter and I want to repair it. I am not going to spend 200 dollars for a new one. I can endure the leak for that solution. I am quite sure the seat has some debris or it needs cleaning. I gave a good pull on the large brass piece on the valves infeed side clamped in a vise and it would not budge. I started to get a cheater but instead, i am asking my fellow steamers.
here is a pic of the valve.
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relief valve.jpg
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Re: leaking pressure relief valve

Post by Mike Rometer » Thu Dec 17, 2015 10:32 pm

Add full pressure to the inlet side and operate the over-ride lever fully. See if that shifts it.
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wsmcycle
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Re: leaking pressure relief valve

Post by wsmcycle » Thu Dec 17, 2015 11:49 pm

I did and it does operate. i hoped something might get blown out of it. tomorrow, i am going to blow backwards through it.
thanks.
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Re: leaking pressure relief valve

Post by DetroiTug » Fri Dec 18, 2015 2:02 am

Not trying to tell anyone what to do, but If it's malfunctioning, it needs to be replaced. The PRV is the last line of protection. Mcmaster-Carr has them for less than 200 I think.

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Re: leaking pressure relief valve

Post by fredrosse » Fri Dec 18, 2015 3:58 am

Ron is correct that safety valves should not be messed with, they should be replaced or be set and sealed (leaded wire seals) by a qualified valve setting organization. This route meets the ASME boiler code rules. Both of these options are expensive. I know that for steamboat pressures, there are safety valves now made with soft Teflon seats, and I am told these are much less likley to weep.

When I had a steam domestic heat-power module, the 150 PSIG safety valve would often leak, and I would dismantle, lap the valve seat with automotive valve grinding compound, then re-set the valve. I probably did this 20 times, and re-setting the valve was no big deal. I then had to run the steam pressure up to pop the valve, and after that the valve would often weep slightly again, a big PITA.

Now my steamer has a proper ASME valve, and it weeps sometimes, is tight at other times. Usually it will weep for the entire day after I accidently pop the valve with improper fire control. Other times it will often not leak at all, provided that I keep steam pressure 10% away from the setpoint. I just live with it this way.

To disassemble the safety valve, you must first remove the setting pin(s) that position the huddling chamber. This setting determines the blowdown of the valve (reduction in pressure after lifting before the valve reseats). Clamp the lower hex assembly in a strong vise, and screw a 3 ft piece of discharge pipe into the valve outlet, use this pipe as a lever to disassemble the valve. After reassembling the valve, the huddling chamber and set pressure must be properly reset, not easy without good steam test bench.
Last edited by fredrosse on Fri Dec 18, 2015 5:18 am, edited 2 times in total.
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Re: leaking pressure relief valve

Post by artemis » Fri Dec 18, 2015 4:42 am

:idea: $ 200 is a lot less than even a cheap funeral service :lol:
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Re: leaking pressure relief valve

Post by Dhutch » Fri Dec 18, 2015 10:36 pm

Obviously if the valve is faulty/misbehaving is needs replacing, but equally if it is working perfectly and just weeps a little when closed lapping it in is the way forwards.

Our boiler inspector has us open one or other of our safety valve at the annual inspection until stainless springs became available.

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Re: leaking pressure relief valve

Post by wsmcycle » Sat Dec 19, 2015 12:36 am

I want to get to the valve seat to clean/lap it. But, i am unable to loosen the body. Someone said to back off the stop screw in order to disassemble it. i tried, but still to no avail. Next, i am going put it in the ultrasonic cleaner. This might expunge the offending debris without disassembly.
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Re: leaking pressure relief valve

Post by wsmcycle » Sun Dec 20, 2015 7:10 pm

The valve operates fine. I test it frequently. I am not being disrespectful its importance. Thanks for your concern.
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Re: leaking pressure relief valve

Post by wsmcycle » Sun Dec 20, 2015 11:28 pm

The valve operates fine. I test it frequently. I am not disrespecting its importance. Thanks for your concern.
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