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Fast cure hi heat silicone?......Cosmo

Cosmo_3 Member Posts: 845
Hey Wallies,

I have run into this situation before and I want a better solution. I have to disassemble the exhaust for a direct-vent boiler I had installed about ten years ago and replace it because the homeowner damaged the pipe (let's just say a home improvement project gone wrong....very wrong). The RTV sealant the boiler manufacturer supplies has a 24 hour cure time prior to operation, I don't have 24 hours. I have been in contact with GE Silicone division, and Dow Corning but still waiting for answers. Has anybody out there seen an RTV (or other) silicone that cures quickly (within an hour or two max), and handle high stack temps up to say 500 degrees F?

Looking forward to your answers/experiances

Cosmo Valavanis
Dependable PHC Inc


  • hr
    hr Member Posts: 6,106
    Try an auto parts

    store. First off, they carry small squeeze tubes, for small jobs. They also have 4 or 5 choices (and colors)in high temperature RTV's depending on the application.

    hot rod

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  • kevin coppinger_4
    kevin coppinger_4 Member Posts: 2,124
    you could use Fastenseal...

    al27c stainless w/ gaskets built in...needs no silicone... comes in 3" and 4" sizes I'm not sure what size you need....kpc

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,226
    another resource

    Hello: This is a resource you should know about!
  • H. Green
    H. Green Member Posts: 22

    Our experience indicates that, although the complete cure time is 24 hrs. The time to safe operation is substantially shorter.

    Before we introduced the Saf-T Vent EZ Seal system with the integral gasket, our seal in place recommendation on cure time was in the order of 3-8 hours, depending on the pressure in the vent. For pulse combustion appliances - you would need at least 8 hours, for more moderate manifold pressures, less than 1.5" wc, 3-4 hours is adequate.

    Most silicone sealants are tacky and no-longer water soluable by this time.

    If you can find it use GE106. It has much better life than the DOW products, though it is substantially more expensive.

    H. Green

  • oil-2-4-6-gas
    oil-2-4-6-gas Member Posts: 641

    permatex 26c red silicone usually 30 minutes for a 1/4 thick bead to cure enough for service and rated at 600 degrees i use this for sealing flue pipe,glueing gasketing, a light bead for steam valves and flanges -of course along with a gasket ,also use it on condensate pumps -to hold seals in the housing , for gasketing --
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