Screwfix compression fittings

[timegoesby]

I recently used some of these and used Loctite sealant on the olives to ensure a seal. Out of 20 fittings 4 leaked and had to be tightened up until creaking. Two where on plastic Speedfit pipe and the olives were wrapped in PTFE as per the Speedfit instructions. Previously I used mainly Conex fittings and never once had a problem. Has anyone else had problems with these fittings? Are they cheap made in China rubbish? Anyone have any recommendations of what and not to use? And who to buy from and not to buy from.

TIA.

[Grunff]

I used a whole load of 15mm and 22mm a few weeks back with no problems.

Are you aware that almost every single item you buy from Screwfix, and most other places, is made in China?

Yes, don't use anything on the olive, no PTFE and no Loctite. Compression fittings form a metal-metal seal, by compressing the olive against the pipe and the fitting. Using anything that might interfere with that can cause problems, and is unnecessary.

[Doctor Drivel]

Put Loctite 575 on the olive. I know of "no" professional who does not use sealant on compression joints, except on plastic pipe where PTFE is to be used. Metal to metal is fine in theory if using high quality fittings and pipe which Screwfix scrap is not. I only ever use Kutelite or Conex compression joints and Typek at a push, the rest are bad news. I have never used Screwfix compression joints as I have never had the guts to try and suffer the wetness. Also use Hep2o pipe not Speedfit, again this stuff can be bad news. Hep2o have "metal" interts while Speedfit have plastic.

May others can give horror stories about Screwfix pipe fittings. The end feed joints look super cheap and nasty too.

[Owain]

But not every item from China is cheap rubbish. Some of it's not cheap, and some of it's not rubbish.

Owain

[Doctor Drivel]

Not sure if this is true. I was told the cheap compression joints have slack tolerances. The fitting bodies are made for Continental 16mm and UK 15mm pipes, just putting in a 15mm or 16mm olive in for the relevant country. That means the UK fitting are slack and the pipes can be skewed a little when the fitting is tightened up. They are relying entirely on the olive to maintain straightness and make the seal.

[daddyfreddy]

I've used PTFE tape on olives and never had any problems. Personally, I'd recommend it to save a lot of hassle.

[Dave Plowman (News)]

I've always used PTFE round the olive and never had problems. At worst it does no harm and at best may help a seal if there is slight marking to the olive or fitting. Of course it won't help if the pipe is damaged etc.

[Andrew Gabriel]

As Grunff said, you do not use anything on the sealing surfaces of compression fittings, or they aren't sealing as designed.

You can use a lubricant on the non sealing surfaces, which are all the surfaces the nut is in contact with. This can help with tighening up the joint first time, and reduce the chance of straining it and distorting something incorrectly. One or two turns of thin (non-gas) PTFE tape makes a good lubricant, but keep it away from the sealing surfaces or you can damage them. Don't do this with gas pipework or you will fail an inspection, as it will be impossible to prove the PTFE hasn't got onto the sealing surfaces.

One other tip -- use the right tools to do up the compression fitting. I've seen adjustable spanners cause the nut to distort very slightly, which will then never seal no matter how much you tighten it up.

[Doctor Drivel]

I know of no pro who does them up cry.

[Heliotrope Smith]

It brings tears to my eyes when I forget the lube and they screech!

[Andy Hall]

I bet that you cried when you had your hacksaw "event" :-)

[Dave Baker]

As the thread has proven you're going to get varying opinions on whether to use sealant or PTFE tape so the conclusion has to be there is no definitive answer. Personally I don't use anything. I think PTFE is a bad thing to use because you don't want anything solidish interfering with the contact between the olive and the nuts. PTFE tape is for sealing threads not olives IMO. If anything a very thin smear of a liquid type sealant can help seal an imperfection on a surface. Loctite is definitely not a good idea. You don't want anything that sets hard and then interferes with the seal if the nuts need tightening a bit more.

What I do is clean the pipe lightly first with fine wire wool making sure not to do this so as to make scratches along the length of the pipe through which water could creep. Instead wrap the wool round the pipe with one hand and twist the pipe with the other so any marking on the pipe is radial. I also do the same with the conical flanges/nuts, especially if they're being re-used, to make sure there are no burrs or water deposits on the sealing surfaces. Finally I check the internal edges of the olive for burrs. One way is to slide the olive onto a spare bit of pipe and run it up and down fast a few times to polish the inside. If it leaves noticeable scratches on the pipe then there's a burr somewhere but that should be gone by the time you take it off again.

Finally don't overtighten. Use a proper sized spanner rather than an adjustable one if possible and mole grips or similar to apply counter pressure to the fitting so you don't strain any other joints coming out of it. Nip up reasonably firmly (which I know is a meaningless description) and then tighten more only if you have to because the fitting weeps. In extremis if a joint just refuses to play ball I use a very thin smear of ordinary clear silicone sealant on the olive and then leave it for a few hours to go off before turning the water back on. Heating it gently with a gas flame for a few seconds to 100c or so will help it set quicker.

[Doctor Drivel]

Some Loctite sealants stay soft.

[Doctor Drivel]

There is. PTFE is useless. Look at a fitting and it achieves nothing. A smear of liquid non-setting sealant is the way. Every pro does that.

The OP has a point, cheapo fittings are waste of time, as are plastic inserts on plastic pipe, so precluding Speedfit and others. The makers of plastic pipes say wrap olives with PTFE tape. Again I can't see what this achieves.

[The Medway Handyman]

Indeed it does, much easier to get the fitting done up properly.

I use one of these

Stanley Locking Adjustable Wrench. Sort of a cross between an adjustable & mole grips, been a godsend on plumbing jobs.

[Dave Plowman (News)]

PTFE under pressure acts sort of like a thick liquid - so really no different from your idea.

IMHO the best sealant these days (although not needed on a compression fitting) is Fernox LS-X. Far better than the traditional ones, but expensive.

[Andrew Gabriel]

Speedfit instructions on the web don't say this at all. They do say you must use copper olives and not brass ones, and you must use pipe insert and ensure the olive lines up with it, and the pipe must be fully inserted into the fitting.

[Doctor Drivel]

to come by.

[Doctor Drivel]

Loctite 575 is far better

[Doctor Drivel]

> a Stanley Locking Adjustable Wrench. Sort of a cross between an

An essential tool, especially two of them. I have seen them for £10 on tool stalls.