Thank you malted hops for the info.
However, I can't believe this is something that was actually used. Honestly.
"Controlled and safe release of excessive pressure reliably prevents containers bursting. That means no danger to people and no risk of collateral damage. With a +\- 145 psi error factor."
Really?
Edit:
I was gonna say it but, decided to look for it instead.....
5. Burst pressure – Stainless steel kegs are rated for an internal pressure of at least 60 to 90 PSI without deformation, with a burst pressure of at least 300 PSI. The safety factors for burst pressure is usually about three to four, so the new keg does not actually rupture until it is exposed to 1000 PSI internal pressure or more. A lot of the new kegs can be purchased with a special pressure relief-valve in the form of a burst disc, which is a small circle stamp on the bottom dome of the keg, which is designed to break out at a certain design pressure to prevent the valve from becoming the weakest point of the pressure vessel. Never intentionally pressurize the keg to more than the design pressure using compressed air, to prevent damage to the keg or worse injuring yourself or innocent bystanders. The reason for this is that while liquid is incompressible, air can be compressed to the point of becoming very dangerous, like a rocket or a torpedo. When de-denting kegs to remove volume impacting dents, it has to be done using liquid and not air, and this procedure should only be done by professional keg service companies.
Again, one would REALLY want to over pressure a keg to set one off. Your standard home air compressor only gets to 135 psi (single stage). One could hook a keg up to a bottle of gas yes......however they would need the other equipment to handle the pressure as well......that's a lot of trouble IMO.