dougg
Well-Known Member
Ive got to change a 50mm sea cock.
What do the memberes think to using PTFE on the threads? or is this a no no?
What do the memberes think to using PTFE on the threads? or is this a no no?
PTFE ?
- Thread starter dougg
- Start date
Contest1
Well-Known Member
PTFE tape, properly applied, will make an improved thread seal and prevent water ingress, widley used as a thread sealant in high pressure steam and chemical pipe work.
It is available in paste form for use with gasket and flange seals., also prevents gauling on dissasembly of threaded joints.
It is available in paste form for use with gasket and flange seals., also prevents gauling on dissasembly of threaded joints.
GrumpyOldGit
Well-Known Member
+1 for ptfe, even use it on the sump plug in my old pickup to keep hot oil inside the engine, works a treat on seacocks too !
vyv_cox
Well-Known Member
The paste version is superb but not usually available through 'normal' outlets. It can be the answer to many difficult sealing problems.
johnphilip
Well-Known Member
Lighter distraction
This always remind me of a work collegue who was nicknamed Teflon. Asking why Teflon I learnt that what ever he was told absolutely nothing stuck!
I find the useful thing about PTFE is that it does not seize up like a plumbing paste so you should always be able to remove it.
This always remind me of a work collegue who was nicknamed Teflon. Asking why Teflon I learnt that what ever he was told absolutely nothing stuck!
nigelmercier
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I got this: http://www.amazon.co.uk/exec/obidos/ASIN/B0082AL3ZQ/dolcetto-21
They also do a smaller pack, but not good value: http://www.amazon.co.uk/exec/obidos/ASIN/B0082AL3L0/dolcetto-21
vyv_cox
Well-Known Member
The one I have was bought in Mallorca. It's in a concertina-type plastic bottle, very convenient to use. Only problem is that it is quite elderly now and the stuff smells terrible.
davidfox
Well-Known Member
Plumbers mate is more robust possibly than PTFE and alledgedly doesnt set/seize up as above
Zagato
Well-Known Member
I did some pipe fitting at the Toyota factory in Burnaston whilst on hols from Uni and we used hessian rope to wrap into the threads with some sort of grease! (big pipes!) Great fun, hungover from the night before, drink at lunchtime, couple of pints after work then back out on the lash in the evening to start all over again! I had to regularly get back to my house by 5.00 am from the bosses girl friends house as he used to pick me up at 5.30 am 
prv
Well-Known Member
We moved Ariam round the corner from the Hamble to the Itchen on Monday, and before leaving had to seal a temporarily unused through-hull fitting above the waterline. The yard let us furtle through their cast-off plumbing box to lash up a set of adaptors and fittings that would work, and the joints were sealed with hemp or hessian string and grease
For real work I use PTFE though
Pete
Zagato
Well-Known Member
Yes could have been hemp, I was always to drunk and knackered to remember, nice girl 
puddock
Well-Known Member
PTFE : Fine for using correctly (NOTE: It is actually described as a lubricant rather than a sealant). We use it all the time offshore on Subsea Wellhead tooling and Production Trees to pressures up to 15,000 psi (The exception being in closed hydraulic circuits where strands of tape can get into the hydraulic circuit)
prv
Well-Known Member
Yep - the reason I like it is it lets me do up fittings tighter than I could without it. They just slide that bit further round.
I'm sure the bulk of it does provide a bit of sealing as well though.
Pete
puddock
Well-Known Member
Of course, we use it purely for its lubricating qualities as opposed to trying to get a good pressure test
Mistroma
Well-Known Member
I had trouble deciding what to use when replacing some ball valves. They were all parallel thread and only one had enough spare thread for a locking nut. I couldn't find anything to seal the large gap at bottom of 2" valve when it was correctly aligned and to stop it coming undone.
I finally settled on Rocol Oilseal as the manufacturers said that it was hard setting but remained flexible and could be dismantled with moderate force. It also has excellent vibration resistance. Being paranoid, I also smeared some Sikaflex (can't remember which one) around the outside of the joint. i.e. Just gripping visible thread and end of valve so that it could be cut free if needed.
No problems with leaks or movement in valves. They all seem rock solid and I'd use it again.
http://www.bes.co.uk/products/213.asp
I finally settled on Rocol Oilseal as the manufacturers said that it was hard setting but remained flexible and could be dismantled with moderate force. It also has excellent vibration resistance. Being paranoid, I also smeared some Sikaflex (can't remember which one) around the outside of the joint. i.e. Just gripping visible thread and end of valve so that it could be cut free if needed.
No problems with leaks or movement in valves. They all seem rock solid and I'd use it again.
http://www.bes.co.uk/products/213.asp
Jamesuk
Well-Known Member
Yes it is good stuff, you can get PTFE thread which was advised for "High Pressure" such as in the Water maker system that I work with
boaterbaz
Well-Known Member
PTFE=Plastic tape for engineers. Technical term
PCUK
Well-Known Member
Sikaflex on the threads will also lock it into place while still being removeable with spanners.
CJ13
Well-Known Member
I'm replacing my Seacocks etc later this year- why shouldn't I use Sikaflex to seal the threads, rather than PTFE tape?
John
John
Mistroma
Well-Known Member
All depends on what you want to achieve. My valves & tails were parallel thread, so would not lock by simply screwing together. I needed something to grip the parts in a particular position and not enough space for a locking nut. I couldn't find 2" fibre washers (or similar) to pack the gap either. I used Rocol Oilseal as it filled the gap between tail & valve plus a few threads as well. I also put some on last few threads when tightening and the whole assembly was solid and leakproof.
I could have used Sikaflex on the threads but I wanted to ensure easy removal if required and the valves are difficult to reach. I did use Sikaflex on the external part of the joint (belt & braces) but that can be cut away when dismantling.
I assumed that Sikaflex on the whole thread would make dismantling very difficult. So, use Sikaflex if you aren't worried about problems next time you want to dismantle the fittings. Otherwise, use something like Rocol Oilseal or other methods suggestioned. I only avoided PTFE because I needed to lock a large fitting in a particular position. I'd have been happy to use it on smaller valves and tighten the valve end against a fibre washer or similar.
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