Why ptfe tape on compression fitting threads

[fredyflame]

Could you tell me why I keep seeing tape round the threads of compression fittings all over the place where professionals must have fitted them?

Surely the seal is on the olive and if you tape up the thread you are working against that seal as the thread should never need to be water tight, or am I missing something?

As a DIYer I lightly paste the olive, never had a problem that a nip with the spanner didn't cure

Cheers

 

[PlumbBobBob]

you shouldn't have any sort of tape on the threads at all as you correctly state the seal is on the olive. probably not professionals who went before, did you find any lost horse shoes?

 

[ecowarm]

Normally a sign of a diy'er imo, but with the influx of "plumbers" serving just a few weeks "time" at the multitude of training schools around the country this trade is being diluted to a handyman or diy occupation

Am I bitter? to right

 

[tamz]

^^ 100% agree with Eco. No "plumber" in the true sense of the word would do that. Pay your money take your chance or people need to get to know your local genuine tradesman which may be hard in a society where most don't know their next door neighbour

 

[SimonJohns]

Just makes me giggle.

 

[Barry98]

waste of money imho , not much but over a year ----

 

[kay-jay]

Water board round here are chronic serial offenders. Every joint on meter connections wrapped. Also every bg customer that's had a magnetic filter installed seems to be taped too

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[scotty plumber]

You normally see ptfe wrapped on the olive not on the thread, i only EVER do this if i am connecting a compression coupling on to poly-ork pipe or occasionally when i use a green ring on to very old copper pipe

 

[Barry98]

i put on the thread on a magna clean , never ever liked meatl fittings going onto plastic , but that might just be me lol

 

[Hardy1]

there is no need to put PTFE tape on a olive as it is the olive which causes the fitting to be sealed Tight.

 

[Dannypipe]

I've had to do it myself in the past, where someone before you has over compressed an olive, to such a point that they've compressed the copper pipe.

It isn't good practise. Then we've discussed putting jointing paste on olives, and the jury was split on that.

 

[mountainman]

I vote for a sliver of paste on a gas olive and a turn of PTFE on water.

 

[kay-jay]

Jet blue on all. No need ever for ptfe unless re-using an existing compression connection

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[Dannypipe]

Oh blimey, we're going to have this conversation again!! :yes:

Ha. I used to use a bit of Jet Blue on everything. However after the last thread on this subject I have been a bit braver and done some 'dry' joints. Not had any issues.

Years of habit though, and hard to break. If a bit of jointing compound flies down the pipe, it could knacker a new tap/ ruin a gas valve.

As I said in the last thread, to avoid this I would compress the fitting, undo it and paste the olive then re-insert. More time consuming but no danger of paste in the pipe work. If it's not vital to keep clean then I will just paste the bevel on the fitting and fit it.

 

[zzzjim]

Deja vu (Compression-thread), stripping joint is a bit like quality control

 

[REDSAW]

when you tape the thread it stops any seepage dripping down the thread, then diverts it up hill so it comes out of the pipe end depending which way you want the water to drip out of.

if neither, then a thumb full of lsx wiped all around the fitting will stop it coming out altogether.
it worked for the guy who installed a boiler i took out the other week, maybe if all the 5 fittings including the gas were more than finger tight he may not have needed it?.

 

[PlumbBobBob]

perhaps he was working to a rule of thumb? thumb size glob of lsx seals anything.

 

[Gray0689]

I've had to do it myself in the past, where someone before you has over compressed an olive, to such a point that they've compressed the copper pipe.

It isn't good practise. Then we've discussed putting jointing paste on olives, and the jury was split on that.

Totally agree Danny
And I use paste on olives

 

[Howsie]

Only used when necessary. Always try to stick to MI when fitting new, anything to make it work on second hand.

 

[leelister6]

Copper olives generally don't need anything on em but the brass ones always get a smear of paste after initial tightening. Based on bitter experience!

 

[thomas donovan]

amen to that leelister6 have had a brass olive on 28mm zone valve start to weep after months while owner was on holiday always wrap a bit of ptfe on olives now, belt and braces

 

[mactatty]

I only use paste on old copper tube (which might have a roughened surface) and never PTFE. PlumBlue or JetBlue is what I use, but B&Q do JetLube for £9.50 for 300g, Screwfix No Nonsense Jointing Compound £8 for 250g. Dear but a tub lasts a long time. Definitely not Boss Green - too lumpy and doesn't stick to pipework, you can't smear it on.

 

[aligorgon]

Shouldnt need ptfe or paste on a compression fitting unless its 28mm or above then i nip the joint loosen and put a dab of jet blue or boss white (heating only) on the olive and re-tighten.

Ptfe may be necessary on a old comp joint or over tightened one.

Only exception is chrome pipe i always use a dab of jet blue on comp chrome fittings.

Generally i try to avoid compression joints cos lets face they arent as reliable as sweated or even tectite fittings.

 

[ne1ls0n]

whats the big deal about ptfe'ing olives? if i dont like the connection it gets ptfe tape round the olive, peace of mind. surely its better to do it than not?

 

[barronbathrooms]

I jet blue every compression fitting/valve just habit I guess but very really get one passing. I hate boss green used to work for a firm that would supply Only boss green as a j/c could never get to grips with it! Alway ptfe magnaclean as well!

 

[SimonG]

As Dannypipe said a fortnight ago, it's one of those you'll never get agreement on. I paste olives and use a twist of ptfe and paste if remaking an old compression joint.

At the end of the day it's all about what works for you to get the job done. For me it works and I'm happy.

 

[glenno1]

I use our lass,nothing gets past her lol

 

[RPG 80]

there is no need to put PTFE tape on a olive as it is the olive which causes the fitting to be sealed Tight.

I find a wrap of ptfe round a olive going onto hep or speed fit plastic, helps prevents the fitting weeping.

 

[Howsie]

I wonder if NASA use PTFE on the o-rings on their shuttle boosters. Maybe they could learn a thing or two from this thread. :lol:

 

[Mike Jackson]

Probably used Boss white and hemp.

 

[wheeto]

I wonder if NASA use PTFE on the o-rings on their shuttle boosters. Maybe they could learn a thing or two from this thread. :lol:

Any idea on the freezing temp of PTFE?

 

[Howsie]

-232 degrees Celsius

 

[ggman]

This debate looks like that we are trying to establish the genderof the Angels: are they male or female?
The compression jointare a strong mechanical union, I personally won't use anything on the olive but I would only using the betterquality joint, expensive but won't gowrong at later date, maybe we have problem when trying to rush the job. Pipes in good condition, nice and clean,copper olives on copper pipes, pipes well aligned fully pushed in and one thingvery important is lubrication of the thread and nut with light oil.
I am a retired electronic engineer, did few years ofplumbing years ago worked a lot on refrigeration
Now you will call me DIYer.
Regards

 

[Mickyplumb]

Been using ptfe on compression olives for 10 years, can't remember ever having a leak ! My train of thought s why take the chance ? Imaging fitting a new heating system, flushing, refilling, adding inhibitor and then finding you've got a weep on on a rad valve ? What a waste of time and inhibitor !!!!

 

[Bernie2]

Hmm!

The original idea of using anything on a compression fitting was because the mating surfaces of both the olive (ring) and the fitting where not always a true smooth machined face and microscopic fault lines that let water pass where said to exist. The UK made fittings claim their machining is so good no jointing paste or tape to fill the imperfections is required. I always use paste however, because its easier to put on than PTFE. Saying that of course you have to go careful how you apply and none goes down the pipe.

 

[adam84]

Ive only used ptfe when the fitting just want stop weeping, as a mechanical fitting it shouldnt need additional ptfe or any other compound if it is installed properly, having said that i got some 22mm compression elbows from a back of beyond of merchants once and none of them would stop leaking without ptfe.

 

[Mickyplumb]

I worked with a lovely old guy about a month ago on an install. He uses boss white and hemp on compression fittings.....I guess old habits die hard !! Still, imagine being the home owner and getting the occasional mouth full of horses tail in your cup of tea!!!! Yuk
Are the new generation of equine critters WRAS approved these days !!!!!!!!???????

 

[WHPES]

Boss White and hemp must not be used for potable systems under water regs as its organic and can support microbial growth. Slic Tite or Hawk Blue are acceptable.

I use Boss White on all non-potable compression fittings and ptfe on potable.

 

[Mickyplumb]

Boss White and hemp must not be used for potable systems under water regs as its organic and can support microbial growth. Slic Tite or Hawk Blue are acceptable.

I use Boss White on all non-potable compression fittings and ptfe on potable.

Yep, i must admit i knew that it can't be used on drinking water, he was using it in an airing cupboard to fit a cylinder, etc.

Having said that, the customer now walks on all fours, has a thick mane of black hair down her neck....only answers to the name of Shergar !

 

[Phil]

Anybody had trouble with Danfoss TRV's lately?

Very shallow fitting depth and a very hard brass olive has resulted in the dreaded wet finger the day after around the pipe.

I always have to PTFE these olives now as three in a row leaking is a right pain.

 

[Koogatubac]

As a apprentice for some strange reason i used PTFE on olives and i used to get the odd weap

When i turned a engineer, i started using jet blue and very very rarely get leaks!
Would be lost without jet blue! Best stuff ever!

 

[RPG 80]

As a apprentice for some strange reason i used PTFE on olives and i used to get the odd weap

When i turned a engineer, i started using jet blue and very very rarely get leaks!
Would be lost without jet blue! Best stuff ever!

perhaps you've got stronger wrists now


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[Phil]

I'll have to get some of this jetblue.

JetBlue | Airline Tickets, Flights, and Airfare

 

[Mike Jackson]

As far as I'm concerned the only time you need any extra sealant is if you are going onto old pipe or re using an old fitting. The last 4 jobs I've done have had no extra sealant used except for the rad valves that I've changed on the old pipework. 2 of these were unvented with no sealant used on any of the compression fittings and no tape used on threaded fittings, just a smear of loctite 577.

 

[ally]

tape on rad valves don't need any on olives unless using old fittings, works for me

 

[adam84]

Anybody had trouble with Danfoss TRV's lately?

Very shallow fitting depth and a very hard brass olive has resulted in the dreaded wet finger the day after around the pipe.

I always have to PTFE these olives now as three in a row leaking is a right pain.

The danfoss are my TRV of choice but agree competely with what your saying, i change the olives but the thread on the valve is so shallow i spend ages trying to dig out a deeper olive. :nonod:

 

[Mickyplumb]

Why ever take the chance of a leak ? How long does it take to run a couple of rounds over an olive.

 

[Best]

Conex olives are a bit deeper, so are good if you wanted to change the Danfoss olives. The olives supplied with Danfoss valves do need you to use a bit of force, but are okay if you use paste & anyhow, paste helps you tighten as it lubricates. Ptfe tape is not as good as paste for sealing olives.
My argument with anyone saying they don't use paste & have no leaks, is - what are all the joints without paste like in a few months & then a few years? Microscopic leaks I think, especially with poor quality fittings or olives.
Never use those olives that are flat, except having a very small tapered edge. Bin them, but if you do use them, use paste, or they leak a bit.

 

[tamz]

Never had a problem with any compressions other than the cheap Italian shyte.
If it is not leaking when you leave it, it won't be leaking next year.

 

[Best]

Never had a problem with any compressions other than the cheap Italian shyte.
If it is not leaking when you leave it, it won't be leaking next year.

What I meant was, you can run your finger around a joint, or a piece of tissue, & it will be dry, but the joint could be leaking very very slightly. So slightly it virtually evaporates I guess. Then you get the white corrosion on lots of the nuts & rest of fittings in a few months/years. Looks terrible & the nuts are seized when you need to do a simple job.
Must admit, cheap Italian brass fittings are the worst for this, but will happen to some degree with others.