Sealing pipe threads

Discussion in 'Help Wanted' started by picklesquirt, May 10, 2020.

  1. picklesquirt

    picklesquirt Member

    Evening everyone,

    Having trouble sealing pipe threads for the starting air for the Blackstone. Using PTFE tape most of the threaded joints give small bubbles at 300 psi with soapy water. Although the compressor gets there it's not what I would like.
    Having Googled hemp as a sealant it suggests it swells when wet so I presume it is best suited to water service.
    Just wondered what other folk have found to be the best sealant for air at this pressure. Pipe is 1in BSP

    Many thanks
  2. campingstoveman

    campingstoveman Active Member

    When I was working we used PTFE on compressed air, only up to 10 bar and never had an issue, I was taught to wind on the tape in the opposite direction to when you were doing the thread up so that the thread didnt push the tape off and to always cover the threads, until they disapeared. According to the RS website PTFE can be used of fuel injection systems which are high bar.

  3. picklesquirt

    picklesquirt Member

    Thanks Martin,

    Your comment of , cover the threads until they disappear is interesting . I am going to strip it down and will reassemble with more generous dose of tape.

  4. hourlapa

    hourlapa Administrator Staff Member

    We use PTFE tape for pretty much everything, water, steam, air although the brush on PTFE is good as well if a little pricey. We buy tape in bulk and apply heavily, don't just stick on a couple of turns :)
  5. Dazzla

    Dazzla Member

    For anything above 1” BSP I prefer to use Bosswhite and hemp. It works well and I’ve never had any problems. It needs a bit more thought when applying than ptfe tape though.

  6. picklesquirt

    picklesquirt Member

    Thanks Gents,

    I have stripped it all down and reassembled with more PTFE tape. Can't test it at present as more pipeing is required to reconnect the compressor in a new location but will let you know the success or otherwise. I've done many trouble free joints with PTFE and normally use about 5 or 6 turns but on radiator tails and small stuff not larger steel pipe.


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