philmac fittings blowing off.

[jonny1977]

hi folks, I have a problem with a fairly new housing project. I have philmac pipe 25mm connected below sinks onto a philmac union and they keep blowing off, I have had scottish water to the properties who have tested the pressure which is sitting at 5 bar, pipework does not have any clips below sink and we have sent a fitting that blew off to get pressure tested which came back ok. pipework to pipe up the sinks is john guest. 1 is blowing off every 3 months. any help would be much appreciated.

 

[oz-plumber]

Can you post a pic of the fitting?

The only ones I have ever had blow off are the pushfit type.
If you don't push the pipe all the way in, you are at risk of the pipe coming out.
With the 25mm pushfit fitting, you could see the pipe slide out of the fitting 10mm or more before the pipe held its place in the grooved olive.

Did you de burr the inside of the pipe and chamfer the outside of the pipe before putting into the fitting?

The ones that you screw the outer nut to connect / tighten the fitting - never had a problem with.