ISO 3503:2015规定了在承受弯曲时，检查机械配件和塑料压力管之间组装接头在内部压力下的密封性的方法。它定义了平均弯曲半径的计算方法以及如何进行弯曲。 根据ISO 3458中给出的方法检查内部压力下的密封性。 本试验方法不适用于熔焊接头。

ISO 3503:2015 specifies a method for checking the leak tightness under internal pressure of assembled joints between mechanical fittings and plastic pressure pipes when subjected to bending. It defines the calculation method for the average bending radius and how to perform this bending. Checking of the leak tightness under internal pressure is carried out in accordance with the method given in ISO 3458. This test method is not applicable to fusion-welded joints.