Division 4.12.2

Seat leakage tests shall be conducted with the inlet of the sample valve connected to a source of gas pressure, the valve in the closed position, and with the outlet open. A positive shut-off valve and a pressure gauge having a pressure range of not less than 1,5 times and not more than twice the test pressure shall be installed in the pressure supply piping and the accuracy of the gauge shall be 1 per cent of the pressure range. The pressure gauge shall be installed between the positive shut-off valve and the sample under test. While under the applied test pressure corresponding to the Maximum Allowable Working Pressure (MAWP), observations for leakage shall be made with the open outlet submerged in water or by a flow meter installed on the inlet side of the valve under test. The flow meter shall be capable of indicating, for the test fluid employed, the maximum leakage flow rates permitted within an accuracy of +/- 1 per cent.