What went wrong with my compression fitting?

[kasser]

I had closed the isolation valve to my outdoor tap a few weeks ago because of the freezing weather and re-opened it today. The compression fitting burst open.

I used a Speedfit pipe with an insert to connect to the isolation valve. The pipe just slipped out of the compression nut, leaving olive and insert inside.

I tried to fit the olive back on the pipe to redo the fitting but the olive was too small. Wouldn't that mean the olive was sufficiently compressed originally?

The same thing happened previously with another isolation valve nearby but in that case, it had been a plumber who had fitted it. At that time I thought he had not inserted the pipe deep enough and tightened it sufficiently, which is why I was careful to do so myself later.

Why would the pipe come off? The connection is close to the main water feed, so pressure would be quite high but I don't see why a compression fitting can't handle it.

Are copper pipes a better choice for a compression fitting? How to ensure the same thing doesn't happen again, especially when I'm not around?

 

[ShaunCorbs]

Did you use the super seal insert as that one you cant use with compression fittings and the pipe normally pops out

 

[kasser]

Yes, I always use superseal throughout for everything, you can see the blue seal on the left in the pic.
Are you saying for compression fittings never use it but the cheaper looking all plastic insert instead?

Also with the superseal I've noticed the pipe doesn't go all the way in because the superseal is quite thick at the front, so if the fitting is not deep enough, the olive ends up tightening up around the insert rather than the pipe.

 

[ShaunCorbs]

Use this type

JG Speedfit TSM15NP Inserts 15mm 10 Pack

And please respond to my pm

 

[kasser]

Not seeing any pm from you?

 

[Scott_D]

Wrong insert as above
It does say somewhere in the instructions

 

[Christopher buzzard]

Happens with copper pipe also. Had it afew times. It's just the expansion in the water when the pipe freezes. No where to go so the pipe pulls out of the valve. You will need to use a new olive when reconnecting.

 

[johnduffell]

Agreed with the above wrong insert, however that's not really your fundamental issue that just made it the weakest point.

if you isolate pipework at risk of freezing, that just stops a flood when the pipe is damaged by freezing. If you want to prevent the damage, you must drain the pipework too.

 

[ShaunCorbs]

Agreed with the above wrong insert, however that's not really your fundamental issue that just made it the weakest point.

if you isolate pipework at risk of freezing, that just stops a flood when the pipe is damaged by freezing. If you want to prevent the damage, you must drain the pipework too.

Or leave the outside tap open if its supplying one

 

[Best]

The power of the expansion when water turns into ice is very strong and can damage iron pipes, so the hydraulic action of the ice will pull the pipe through the olive.
Copper pipe will just split open when frozen if it can't come off a fitting

 

[davhill]

Just a little something from experience. I have a 13-tread fire escape with rectangular section steel tube handrails. One of these got water stuck inside and it froze. The bottom 3 feet went piggy bank shaped and I had to weld in new metal. All parts with closed ends now have a drain hole.