Division 4.2.15.2 Procedure and Requirement

The container shall be pressurised to ≥ 1,5 times nominal working pressure. Under no circumstance may the pressure exceed the auto-frettage pressure;

The pressure shall be maintained for at least 30 seconds to ensure complete expansion. If the pressure cannot be maintained due to failure of the test apparatus, it is permissible to repeat the test at a pressure increased by 0,7 MPa. Not more than two such repeat tests are permitted;

For type 1, 2 or 3 containers, the manufacturer shall define the appropriate limit of permanent volumetric expansion for the test pressure used, but in no case shall the permanent expansion exceed 5 per cent of the total volumetric expansion measured under the test pressure. Permanent expansion is defined as the residual volumetric expansion after the pressure has been released;

For type 4 containers, the manufacturer shall define the appropriate limit of elastic expansion for the test pressure used, but in no case shall the elastic expansion of any container exceed the average batch value by more than 10 per cent. Elastic expansion is defined as the total expansion less the permanent expansion (see point (c));

Any container that does not meet the defined expansion limit shall be rejected, but may still be used for batch test purposes.