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Steam Pipes and Owens Foamular 150 XPS Foam

Marc_J Member Posts: 12
We have a 1922 home with a one-pipe steam system. We are in the process of insulating the concrete walls in our basement. There are several locations where a steam pipe riser is making contact with the Owens Foamular 150. Owens is saying that their product should not be in contact with surfaces where the sustained surface temp exceeds 150degreesF. I suspect that the exterior surface of a steam pipe may exceed this but having trouble confirming it. Anyone have experience with this? I can leave a gap around the pipe and fill it with Great Stuff (good up to 240degreesF) but would prefer to avoid the extra work if it's not necessary.


  • Brewbeer
    Brewbeer Member Posts: 616
    The outside of a steam pipe riser supplying steam to radiators will easily exceed 150 F, but the best way to be sure is to measure it. You can check the actual temp with an IR gun if you have one. you can also use a lb thermometer or a candy thermometer.
    Hydronics inspired homeowner with self-designed high efficiency low temperature baseboard system and professionally installed mod-con boiler with indirect DHW. My system design thread:
    System Photo:
  • Jamie Hall
    Jamie Hall Member Posts: 15,856
    The outer surface of a steam carrying pipe will be at, or very close to, 212 F. Great Stuff or products like that will survive, but they will degrade very quickly. It would be much better to insulate the steam pipe with an inch of fibreglass insulation made for the purpose, and then bring your foam up against that.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    EBEBRATT-Ed Member Posts: 9,012
    what @Jamie Hall said
  • Chris_L
    Chris_L Member Posts: 206

    Great Stuff or products like that will survive, but they will degrade very quickly.

    This hasn't been my experience. I used Great Stuff to seal between all of my radiator risers and the floor. After at least 10 years, the foam has discolored, but there is no obvious degradation.

    I've also used it to fill the gaps in my less-than-expert miters of fiberglass pipe insulation around fittings. While this was only a year ago, I haven't noticed any degradation there, either.
  • BobC
    BobC Member Posts: 5,190
    The heat may discolor or even deform the foam sheet but the effects will be cosmetic.

    Smith G8-3 with EZ Gas @ 90,000 BTU, Single pipe steam
    Vaporstat with a 12oz cut-out and 4oz cut-in
    3PSI gauge
  • Marc_J
    Marc_J Member Posts: 12
    Thanks for the info folks!
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