Air testing stacks

[stings27]

Evening all.

I work on new build and have been informed by NHBC that all stacks are now to be air tested (polypipe ring seal)
The company I work for have supplied all the relevant equipment (all new) and was advised by a work colleague to use plenty of silicone grease on all joints and also on bags and bungs.
The first 2 stacks I tested have failed ( even tho there was no problem on a wet test) and after using a complete tin of LDF, couldn't find one leak :90:.
Any advice? Been told its easier to test solvent weld opposed to ring seal which can be a pain in the Rs to resolve.

Thanks :cool4:

 

[chris watkins]

Access doors on each floor to break down the testing so you can narrow down the area leaking but it is nearly always access caps / doors & testing equipment itself so alway go for these first.

Always used S/W or cast so don't know the difference between push fit but never had a problem with under ground.

 

[tamz]

Don't use grease on bungs or bags. If you are using canvas bags soak them before you use them but they are still a pita. Pvc or rubber bags are much better.

 

[mfgs]

Nearly always the test bungs, the cheap ones leak from the middle around the thread. Bags are much better to use where possible.