I've got 2 composite 10kg/22lb gas tanks which have both expired in 2017. I got them from my father some years ago, he told me they couldn't be recertified because they were discontinued or something. I figured I could use them as air tanks for my pneumatic projects so I purged them, making sure there was no propane left in them.
About 2 years ago I noticed the rings around the necks of the tanks said: country of origin - some numbers - PH 30BAR - 12.0L. So the test pressure of these tanks is 30 bar. For some reason I then decided to pressure test them using a HVAC scroll compressor. I took the entire setup to a safe place and filled them to 30 bar. After leaving the tanks for a while I stored them in a shed, still filled. Some months later while cleaning up the shed I emptied them. I didn't check the pressure of the tanks, but there seemed to be a reasonable amount of air in them.
I haven't used the tanks since, until today. While filling one of the tanks to 4 bar I noticed it was leaking at the neck. I filled the other tank to 7 bar and it seems to be fine. I was kind of surprised as they seemed to have survived 30 bar of pressure and are meant for propane, which of course, shouldn't be leaking out of a tank.
Does anyone know what might've caused the tank to leak?
Factors which may've had influence:
Storing them at 30 bar
Possible temperature changes while storing
Small amount of oil in the tank from the HVAC compressor
About 2 years ago I noticed the rings around the necks of the tanks said: country of origin - some numbers - PH 30BAR - 12.0L. So the test pressure of these tanks is 30 bar. For some reason I then decided to pressure test them using a HVAC scroll compressor. I took the entire setup to a safe place and filled them to 30 bar. After leaving the tanks for a while I stored them in a shed, still filled. Some months later while cleaning up the shed I emptied them. I didn't check the pressure of the tanks, but there seemed to be a reasonable amount of air in them.
I haven't used the tanks since, until today. While filling one of the tanks to 4 bar I noticed it was leaking at the neck. I filled the other tank to 7 bar and it seems to be fine. I was kind of surprised as they seemed to have survived 30 bar of pressure and are meant for propane, which of course, shouldn't be leaking out of a tank.
Does anyone know what might've caused the tank to leak?
Factors which may've had influence:
Storing them at 30 bar
Possible temperature changes while storing
Small amount of oil in the tank from the HVAC compressor
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