As per Indian Standard 8451: 2009 , it is mandatory that all the vehicle owners running their vehicles on CNG should get their CNG cylinders hydro tested every three years.

All CNG run vehicles should have compliance plate affixed at appropriate place on the vehicle and ensure their CNG cylinders hydro tested every three years with valid hydro test certificate as per Gas Cylinder Rules 2004. The date of last cylinder testing should be punched on every CNG cylinder and compliance plate.

PESO Authorized agencies where hydro testing of CNG cylinders can be done.

Non-adherence to the above may result in refusal to fill CNG at station and may render you liable for prosecution