Capping Stubs

[bobloes]

I did the plumbing in my daughter's bathroom in October last year after she had knocked a wall down between the bathroom and an adjacent toilet. It involved the removal of a toilet system and moving the sink three feet to the left. The previous plumbing used PB barrier pipe and what I can only describe as metal plumbfit connectors. I decided to cap the pipes which were no longer required and I used 'quick fit' caps. I have used these before in my own house and have had no problems in the last eight years. One difference is that her complete system is mains pressure, mine is low pressure.
One of the capped stubs came off with a hell of bang on Sunday. Fortunately we were in the house and reacted quickly to minimise the water damage. I will now replace the pipe and remove all of the stubs.
Two questions. Would professionals not cap stubs except for a very short usage time? Is this 'blowing off of a cap' an uncommon occurence or has she just been unlucky?
I cannot be 100% sure that I used an insert with every connection and I accept that it may be my incompetence with fitting that could be the reason. Thanks.

 

[PrenticeBoyofDerry]

The caps should work better under pressure providing fitted correctly.
I do prefer copper fitting though and even on the occasions I have worked with plastic pipes still use copper compression rather than speed fit.
Be aware that you don't have any dead legs when capping off. Try to have the leg of pipe that is capped, no longer than one metre in length.

 

[bobloes]

Roger that. The legs (stubs?) are only about 10 cm max. I agree re the compression joints, generally what I have used as well as I have never worked with plastic until now.

 

[doitall]

Did you use an insert and the same brand as the pipe fittings

 

[bobloes]

Cannot be certain, I thought the inserts would not be 'brand' specific.