Pressure barrels, what's going on?

[terrym]

Wouldn't the PB bulge like the one below long before exploding?

Bulging pressure barrel thread - https://www.thehomebrewforum.co.uk/threads/pressure-barrel-bulging.65299/

You might be right. All mine used to bulge and I never overprimed, the opposite in fact.
But every time the PB goes through a pressure cycle it get slightly weaker. Thats why they ultimately fail as I have found out with pinhole leaks or cracks in the body seam. I've even had a cap crack and then leak.
However that's incidental to my point which is modifying a PB or hooking up a compressor to a PB is not safe practice, as is testing with air alone, especially on old or second hand PBs of unknown history. The rubber bands that protect these items are crude and should only be designed to lift and discharge at a rate in line with a slow fermentation process not cope with the flow from a compressor.
Anyway I've said my bit now, and more besides.
Others can take heed or ignore what I have said, its up to them.

 

[Chippy_Tea]

Anyway I've said my bit now, and more besides.
Others can take heed or ignore what I have said, its up to them.

Thanks for explaining as it may save someone having a nasty accident.

I only asked the question above because i remembered seeing a picture of a bulging PB so searched the forum, obviously they are not meant to bulge so damage is being done when they are at that pressure.

 

[terrym]

....they are not meant to bulge so damage is being done when they are at that pressure.

I think they inevitably do bulge under pressure, and its expected, after all they are manufactured from HDPE which does have a little 'stretchiness', but this in itself isnt unsafe since the design should take this into account (hopefully ). If they were proven to be unsafe through 'normal' use they would not be sold. However its the cycling that slowly weakens them as I said and that will probably lead to their ultimate failure. The build quality on the ones I used was not very good and that leads to a lottery on when they do fail. Some might be lucky and get years, others months.

 

[Roger Wilko]

I have had 2 pressure barrels, one a cheap budget job and the more expensive rotakeg. Both have been a complete pain, chasing leaks, ok for a couple of brews then leaking again. Finally gave in and bought a cornie keg last month, why I wasted all that money on plastic kegs when for the money I have spent on them I should of bought a cornie straight away. I’m so impressed and no need to secondary prime .