Hydro Testing

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jlakes85
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Hydro Testing

Postby jlakes85 » Tue Jun 20, 2017 8:46 pm

Hi All,

I'm in the midst of hydroing the dry pipe and aux pipe for the shay. Im having some issues getting everything absolutely leak proof so I don't loose 30+psi per drop. What would be the recommended tape/dope for the thread fittings. Also what would work best in steam service?

-jlakes85

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SteveM
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Re: Hydro Testing

Postby SteveM » Tue Jun 20, 2017 8:55 pm

Not sure about the live steam world, but my plumber prefers the liquid brush-on dope to the tape.

Steve

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FLSTEAM
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Re: Hydro Testing

Postby FLSTEAM » Wed Jun 21, 2017 6:22 am

PTFE Pipe dope available at Lowes, HD or ACE

JB
http://www.ngshay.com/
Shay drawings and castings

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Bill Shields
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Re: Hydro Testing

Postby Bill Shields » Wed Jun 21, 2017 3:58 pm

Here is a never-ending discussion...tape or dope or Loctite thread sealant.

Plumbers (in general) tend to go with what is quick and easy and generally don't have to deal with steam. They DO have to work with propane and natural gas where the paint on dope is pretty much required (gasoila?)

In most cases the biggest difference is in how the stuff is applied (carefully) and in some cases how well the threads are cut.

be careful with everything so that you don't get the 'sealant' down inside the pipe and gunked up into all sorts of places you don't want it once the threads are made up. Our little needle valves, INJECTORS, etc: often do not react well to this stuff inside the lines where only water is expected.

I cannot say that I have ever had a totally water-tight (no leak) cold hydro..it goes with the territory.

I can say that most of the steamers I have ever seen / worked on / built, tended to leak a little here and there until they were good and hot and ready to stop leaking on their own good time.

jlakes85
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Re: Hydro Testing

Postby jlakes85 » Wed Jun 21, 2017 7:50 pm

Hi Bill,

Sounds good. I guess I might have to lean on the pump handle a bit for the full 15 min to keep the Needle on 400 psi

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Marty_Knox
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Re: Hydro Testing

Postby Marty_Knox » Wed Jun 21, 2017 9:33 pm

Why are you testing to 400 PSI? Are you going to run at 200 PSI?

jlakes85
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Re: Hydro Testing

Postby jlakes85 » Wed Jun 21, 2017 9:48 pm

Hi Marty,

Design pressure is 125 psi.

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Bill Shields
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Re: Hydro Testing

Postby Bill Shields » Thu Jun 22, 2017 6:46 am

ok...so again the question...why 400 psi.>>>?????

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Marty_Knox
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Re: Hydro Testing

Postby Marty_Knox » Thu Jun 22, 2017 7:00 am

We make the initial at twice working pressure, retests at 1 1/2 working pressure. There is no advantage to exceeding this. In fact, there are some inspectors who will condemn a boiler that sees more than twice working pressure.

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NP317
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Re: Hydro Testing

Postby NP317 » Thu Jun 22, 2017 9:23 am

Washington State Boiler Code declares that a hydro pressure test more than 200% of Maximum Allowed Working Pressure results in a damaged pressure vessel.
This causes the State to downgrade the MAWP.
Know your local Code.
~RN

jlakes85
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Re: Hydro Testing

Postby jlakes85 » Thu Jun 22, 2017 11:15 am

Hi All,

Excellent information as always. I'm glad I was just testing only the dry pipe and aux pipe to start. These are comprised of 3/8 class 3000 fittings and sch 80 threaded pipe.

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Harlock
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Re: Hydro Testing

Postby Harlock » Thu Jun 22, 2017 12:38 pm

I have been very happy with LocTite 567 High Temperature Thread Sealant with PTFE. I have not used thread tape in a very long time.
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