ISO 13259:2018 specifies a test method for determining the leaktightness of elastomeric sealing ring type joints for buried thermoplastics non-pressure piping systems. Unless otherwise specified in the referring standard, the tests are carried out at the following basic test pressures: p1: internal negative air pressure (partial vacuum); p2: a low internal hydrostatic pressure; p3: a higher internal hydrostatic pressure. It also describes the following four test conditions under which the tests are performed: a) Condition A: without any additional diametric or angular deflection; b) Condition B: with diametric deflection; c) Condition C: with angular deflection; d) Condition D: with simultaneous angular and diametric deflection. The applicable selection of the test pressure(s) and the test condition(s) is specified in the referring standard.