Sealing BSPP fittings

18 Jan 2008
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United Kingdom
I have a radiator with BSP parallel threads. I want to fit BSP-male to 15mm couplers and use a shaped piece of 15mm pipe to connect to the radiator valves rather than using standard tails. I've bought some straight couplers from Screwfix (item 67110). I expected these to some with rubber or fibre seals but they didn't. The bleed valve and plug came with the radiator and have rubber O-rings to seal them. I presume I need the same to seal the couplers.

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You need to wrap PTFE tape around the thread.

Approx 8 turns clockwise, viewed from the open threaded end. Or, you could put some liquid PTFE on the thread instead.

You don't need PTFE on the thread for the compression nut, but a smear of jointing compound (eg. Boss White) on the olive will help the seal. ;)[/url]
I thought PTFE is for tapered threads, not parallel ones. OK, I could bung it up with PTFE, but is that really the proper way to do it?
PTFE isn't a bodge. It's an effective way of sealing threads, and the successor to messy hemp and paste.

OK for parallel as well.

See video on my previous post's link.
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I thought PTFE is for tapered threads,
Female bsp threads are always parallel; male can be tapered or parallel.
Tapered needs teflon tape, parallel male needs washer or o-ring depending on design.
PTFE is OK, Loctite 55 (floss type stuff) is better. You can use it wound round the threads , or it'll make a very effective washer under the flange of the fittings you have.
parallel male needs washer or o-ring

That's my understanding. I can see that PTFE / Loctite 55 may work, but I don't think it works by design.

So, going with the washer approach (apologies to all the PTFE promoters for now - I may be back with you when the washer leaks!) what sort of washer or seal do I want? I've seen a few fibre washers advertised as suitable for 1/2 BSP tap connectors, but they're too small.
Hemp and paste will stop any leak - because the hemp expands with the moisture - if it was good enough for Nelson`s Navy it`s good enough for me - but not the Thought Police and their poxy bureaucracy- fill in a Risk Assesment and submit it to the local Building Control :rolleyes: In Triplicate

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