Compression joints and tapoured male /parrallel female joints

[saltyrob]

Hi Folks,

Will be doing some plumbing and any advise /tips on making sure connections are done correctly would be much appreciated.


Many thanks

Rob

 

[Seajet]

Use PTFE tape wrapped around a few times, in the direction where tightening the nut will go along with it rather than ruffle it up.

Fernox LSX in a tube is good, but can be a bit messey - and a tad pricey but probably worth it if you are not too sure.

Do dry runs of all joints first to ensure threads are clean, before applying tape or LSX.

If unhappy don't just keep going, if at all possible stop then sleep on it, all will be clear in the morning !

 

[sipsiwn]

Many moons ago, having set about a major pipe wrestling session to get radiators into the new 'rooms in the roof' just completed, the best advice I had was, make sure any cut ends on copper pipe are cut square, any burr is removed, then clean the pipe end with fine emery cloth/paper to make it shiney before putting it into the compression fitting. Amazingly nothing leaked and the kids no longer went blue in the winter..

 

[RichardS]

Use PTFE tape wrapped around a few times, in the direction where tightening the nut will go along with it rather than ruffle it up.

I don't know whether you are doing water or gas pipes but it's best to use the thicker impermeable stuff for gas work. You can use the thicker stuff for water but don't put too many turns on.

Unlike the plumbers who built our house, I never use PTFE on compression fittings but it's surprisingly common as a "belt and braces measure". I reckon it's bad practice!

Richard

 

[David2452]

A little liquid PTFE on BSPT, nothing on compression joints, use a pie cutter not a saw and only apply a little pressure on the screw down cutter at a time, though I prefer a diameter specific spring pressure cutter, they will both make a nice curled end without external burrs, deburr the internal with the tool usually on the cutter. Use half hard copper tube, don't go mad with tightening the compression nut, 3/4 to a full turn should do it from snug. Or just use Tectite fittings, much nicer especially if visible.

 

[VicS]

Hi Folks,

Will be doing some plumbing and any advise /tips on making sure connections are done correctly would be much appreciated.


Many thanks

Rob

PTFE tape and jointing compounds are not necessary and should not be used on compression fittings. Do not overtighten them either. If you start to distort the pipe it will probably leak. ( as David says 3/4 turn usually sufficient)


Parallel threaded joints should tighten onto a joint washer


Tapered threaded joints will require tape or jointing compound. Dont over do the tape you only need enough to seal the threads

A common plumbing bodge is to use a tapered male into a parallel female. Tape will be required. You'd not get away with it for hydraulics, high pressures or in aeronautical engineering.

 

[ffiill]

Compressions are just that and if made properly do not need anything else.
BSP tapers are better than parallels but you do not have any room for adjustment.
If you are without PTFE tape then Duct tape works as well.

 

[nigelmercier]

If you are without PTFE tape then Duct tape works as well.

Surely you jest.

 

[Iliade]

use a pie cutter

A man after my own heart!

 

[Seajet]

I worked as an emergency plumber for 5 years, and while compound like LSX was sneered at, I can assure people like Vic-S that PTFE is definitely to use on compression fittings.

I have never heard of duct tape being used and don't fancy it, much too thick.

I have never heard of a tapered male into a straight female, that's a real bodge.

My initial engineering training was in aviation.

Saltyrob,

I'm sure you won't need this, but remember as an emergency measure if it all goes horribly wrong, kinking a pipe by bending or even hammering will stop flow !

No I've never done that but it's as well to be aware of Plan Z...

 

[RichardS]

I worked as an emergency plumber for 5 years, and while compound like LSX was sneered at, I can assure people like Vic-S that PTFE is definitely to use on compression fittings.

As I mentioned above, that fits with my experience having taken out and refitted a fair number of domestic bathrooms and heating systems but I'm very surprised that it is a recommended procedure. I personally have never used PTFE with compression fittings as I instinctively feel that it is likely to increase the chance of a leak rather than stop it. Perhaps I am wrong?

Richard

 

[Seajet]

Richard,

the PTFE gives something to ' bite ' on; if you tried joining super-smooth shiny stainless pipes you'd find they can be a right pain !

Obviously one needs to use enough to have an effect but not too much to create a lump, about 3 turns seems to do it.

 

[VicS]

I can assure people like Vic-S that PTFE is definitely to use on compression fittings.

.

Oh no you can't!

 

[Seajet]

I can't ?

I'd better tell my ex-boss and all my colleagues then who also use PTFE.

Standard practice on household plumbing; not for stainless.

How much professional plumbing work have you done, BTW ?

 

[bedouin]

For compression joints PTFE is not necessary - the water tightness does not depend on sealing that thread. Don't over tighten the joint - do it to finger tight then about half a turn with the wrench

 

[VicS]

Hi Folks,

Will be doing some plumbing and any advise /tips on making sure connections are done correctly would be much appreciated.


Many thanks

Rob

For copper tube soldered joints possibly a better choice than compression fittings, unless its stuff you will want to undo periodically. There is a choice of solder ring fittings which already contain the solder or end feed fittings where you feed the solder in yourself. Use lead free solder for drinking water.

Push on fittings are useful too esp in difficult to get at, or dangerous to solder with a flame, places

 

[VicS]

For compression joints PTFE is not necessary - the water tightness does not depend on sealing that thread. Don't over tighten the joint - do it to finger tight then about half a turn with the wrench

The bodgers wrap the tape round the olive! The absolute max to consider is a light smear of compound ( eg Boss white) on the end of the pipe, after fitting the olive, where it goes into the body of the fitting

 

[Seajet]

Funny how an hobby amateur calls using PTFE a ' bodger's ' practice, when I was taught it at college, and the lifelong plumbers I worked with use it.

Yes soldered joints are better, but the OP's question was re compression joints, and doesn't seem very confident; so instead of pontificating from on high I have given the hints he needs to actually get a result.

I have never bodged anything in my life and and at Kingston college attained merits in both papers and practical work, also the highest mark ever attained at that college and time.

When I did work in this field, it usually involved high status hones and businesses; a combination of health and wish to follow a lifelong ambition means I stopped doing paid plumbing a few years ago.

As some people on here are obviously born plumbers and know what it actually involves, I'd be happy to give you details of the company I used to work for before going self employed.

 

[gordmac]

Although it is used to seal, I was under the impression the primary function of PTFE tape was as a lubricant.

 

[RichardS]

Although it is used to seal, I was under the impression the primary function of PTFE tape was as a lubricant.

That can't be the primary function with tapered fittings. If you put oil, silicone or graphite lubricant on a tapered fluid or gas joint I'm 100% sure that it will still leak.

Richard