A pressure test verifies that the inner vessel, piping, valves and safety devices of a cryogenic ISO tank container remain safe to operate at their design conditions. It is part of the statutory periodic inspection every tank container must pass every 30 calendar months to stay in service.
The pressure vessel and safety relief valves (SRVs) are pneumatically pressurised to the working pressure shown on the tank’s data plate. The tank is checked for deformation and leakage and the SRV’s must open and close at the set pressure. The inspection also includes an external examination of the vessel, frame, piping and service equipment, a leak test, a functional check of all valves and fittings and, every 5 years, inspection and re-calibration of the safety relief valves.
The majority of Bofort’s tank containers are UN-type T75 portable tanks built to carry and store refrigerated liquefied gases. They are built in accordance with the ASME Code Section VIII Division 1. They follow the periodic inspection regime of IMDG and RID/ADR regulations: an initial inspection and test before entering service, followed by inspections at least every 2.5 years. For vacuum-insulated tanks, the regulations allow the internal examination and pressure test to be replaced by a leak test and a vacuum measurement, subject to the competent authority. Completed tests are dated and stamped on the tank data plate and certified by a periodical test certificate.
