Hello, Quick question about compression joints. I did a few of these years ago when we moved into our house, all are still fine. But need to replace a washing machine valve, so was refreshing myself on compression joints by looking on the internet. It seems that most people recommend using PTFE tape and/or "grease" (not sure of the right word for the stuff). But I never used anything before and they have never leaked. So is it really necessary? Actually it's got me very confused and I've lost confidence in doing it myself now. Must be age! So what gives? Do I need PTFE and "grease", or can i get away without it? Thanks, Adam
You can do them up dry but using a smear of paste helps with lubrication and seal.do not use PTFE tape as that is a bit of a bodge. https://www.screwfix.com/p/fernox-jointing-compound-400g/21548 Remember when using a compound on water pipes that it is suitable for potable water.
This always seems to set off a lot of arguments. I'm not a plumber. What I do, provided it's somewhere accessible (which I would always want a compression joint to be). Do it up, don't over tighten. If it weeps, keep nipping it up bit by bit until it stops. If it's still not having it, take it off, bit of jointing compound or PTFE on the olive, reassemble. In principle shouldn't need jointing etc, but I guess the quality of these things varies. My plumber always uses jointing compound - I guess because it's insurance, you do it up, you can walk away without worrying about it weeping, no callbacks.
In essence... A compression joint seals by having the olive "grip" on both it's inside and outside... The inside of the olive grips the pipe, and the outside of the olive is "pushed" against the fitting and the nut. The seal is made by the compression/deformation of the olive against the corresponding bits, the pipe and the fitting, (the the deformation is only slight) Using PTFE tape around the olive is basically introducing a barrier to that seal. Using something else more "fluid", such as Fernox FSX, (which is like silicon sealer designed for compression joints), can help. It doesn't impede the compression joint, but can act as a "micro filler" meaning the olive doesn't have to compresses quite as much, and doesn't need tightening as might, (though it still needs to be tight). If all part are clean however, just dry is fine for a compression joint. On a taper thread joint, where there is no olive, and the seal is made by the thread tightening up on the taper, is where PTFE should be used. The tape does act as an actual sealer in this instance, because the surfaces of the threads aren't precision enough to create a good seal. At least, speaking as a DIYer, that's my understanding... and it's always worked for me. Good luck, Regards, Cando
you should set an olive in a fitting designed for it torque it up to the correct setting for the material size etc then remove and fit it in the fitting no one dose put in through nut and olive tighten up a bit open up if leaks tighten up bit more or ptfe olive or plummers mate the olive or both or change the olive for a soft one if using old fittings soft one being a copper not a brass one if overtighten the nut will split but you prob want see it until it leaks
Plumbers Mait is for Sanitary Ware not compression fittings, PTFE screams of a diy job and not something a time served Plumber would do on a new fitting.
Know what you mean dog giving the full picture As for full time plumber no one has mentioned how to put a fitting on correctly And no one has said the correct thing is to re new it so tell everyone Not only a plumber but sparky and gas fitter roofer fitted windows doors you name
I put tiny dab of vasiline on the thread. Tiny bit.. So easy to do up and judge the force vs dry and it grinds and binds.. No PTFE tape... On a side note.. The more people you ask the more different options you will get so I guess its whatever works for you.. Over tightening as that is the biggest problem imo. Just a gentle nip up and make sure pipe is clean
When I was training 45 years ago on day release plus one evening every week for 4 years it was instructed: Make sure every mating part is clean then do it up finger tight plus half a turn with a spanner to nip it up.
agree and that will give the correct torque for that type of fitting others will be different s/s is a turn and a qurter and all should be set in a former and tested with a torque spanner but as you know they never are
Hi I’ve actually retired now, but I’m still involved in my company, we use press fittings now . It’s more economical would you believe ! Because we work in schools and public buildings, not using flames or hot work, the insurance is a lot less than the cost of fittings. And as you all know, trying to solder a pipe with a bit of water in it is a pain ! So, with the press fitting, is a lot quicker. Regards Peter
How many plumbers carry a pump and remove water from pipe? Only ever seen one use a pump and I thought brilliant... Was a pump that is used with oil change on car instead of removing sump plug. Cheap enough and worked a treat removing water from pipe
Some brass compression fittings and olives vary. The threads can be a bit tight, or slightly flawed and ‘feel’ as if joint is compressed. Some olives are very heavy metal, or a harder type of metal and hard olives can be near impossible to compress. Personally I would say each type of fitting can require different force to compress the olive and it is best done using paste as a fine sealant and helps lubricate the joint. Also I prefer to undo the joint to check olive is compressed and full on.
They certainly do, expecially comparing brass and copper olives. Ease of compression is the main reason copper olives are specified when using compression fittings of plastic.
Yes, the soft copper olives mould to the soft plastic pipes. Although quality brass olives are better on metal pipes on heating systems as heat won’t cause movement and risk of slight weeps through time
Yes I agree fittings have always have varied, teaching technique was as a rule of thumb, experience and knowledge follows later.