A recent 'home improvement' programme on tv showed someone fitting a compression joint onto copper tube ... they put the olive on the tube first and then wrapped PTFE around the bit of tube which goes into the fitting. Is that right? I've always used it on the thread. Doesn't their way stop the olive from seating properly???
The olive is soft tempered so that it makes a good seal between the copper tube and the chamfer in the brass compression fitting. No need for PTFE tape or yesteryear's equivalent, Boss white. The PTFE tape may act as a lubricant on the screw threads but arn't necessary and the screw threads of a compression joint play no part in the seal.
Big misconception about PTFE tape - many people seem to think it is some kind of sealant. It is however a lubricant. Putting PTFE tape on the threads of any metal to metal junction will make turning it far easier with far less of risk of damage to the threads. That's where it should be used if at all on compression joints. Tango
PTFE Tape is a sealant, it is used on screwed threaded joints, it should not be used on the olive of a compression fitting
I've often wondered about that so I looked it up to prove R.P. wrong & found that everyone described it as thread sealing tape, like he said. Sorry about that Tangoman.
Couldn't agree more. Bl**dy tennis pops up unexpectedly on TV while I visit the bog, go down the garden, or when I'm busy on this PC & can't turn it off fast enough. It spreads like a virus to channels where I'm used to seeing something interestng. Sorry about that. back to PTFE tape.
I told you it was a common misconception. Of course we're really talking semantics here, since it could be argued that it is sealing the threads, however, you can fit a compression joint perfectly easily without it, and they never leak through the threads! At the end of the day it doesn't really matter what you think it does as long as you use it in the right place, and there RP and myself are in complete agreement - use it on the threads, not the olive! Tango
ps I may not have the experience in plumbing of some of the notables around here, but I do have a long background in chemical engineering, and there isn't much I don't know about PTFE, including it's chemical structure, physical properties, how it's manufactured, who discovered it.........
Pegler's advice is: 'Jointing compounds or sealants are not necessary with PRESTEX fittings; the use of these materials could impair the efficiency of the joint and may contravene local water regulations.' As for PTFE on compression threads: 'A drop of light machine oil on the threads will facilitate tightening (particularly on larger sizes).'
I'm with Tango on this one. PTFE is a low friction material. It is the material frequently used in proprietary bridge bearings that are designed to accomodate the expansion and contraction of a bridge deck. The PTFE packs in the bearing provide a low friction surface that will allow the contact surfaces to slide or rotate relative to one another thus avoiding the build up of stresses in the bridge deck that would result if it was restrained from moving.
Well for years I wrapped PTFE tape around the threads but thought little of why I was doing it other than it was a sealing agent. I saw that programme on telly where the bloke suggested wrapping the PTFE tape around the olive and I thought that that was sensible as it would enhance the joint. Now I realise that this was all cobblers and PTFE is not really necessary. People will be saying that you cannot believe anything you read in the Sun next!!! DWD
I'm an engineer by trade and use PTFE tape for the prupose of lubrication .... mostly to prevent the joint 'sticking' later on. I understand that it doesn't help to seal a compression fitting, but it does make it easier to undo at a later date. Did anyone notice the same presenter paint the wrong side of the front door
They say 'the camera never lies'. True, but it can omit details. Id be very suspicious that many of those makeover programs take shortcuts on the electrics and plumbing to save time. Isn't there a new programme covering the disasters of these lifestyle shows?
They are careful never to show close-ups of the finished article either! Sometimes you catch a glimpse of a skirting or something and it's all suddenly very obvious that preparation suffers in the name of speed. When we were house hunting a year ago we saw some hideous sights ... all inspired by make-over shows. They have a lot to answer for but I guess they keep Dulux busy.
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