Applies to sockets with a primary element of copper-zinc alloy (brass) with a threaded connection on one side and a bonded socket on the other side which are connected by means of a suitable adhesive to pipes of unplasticized polyvinylchloride (rigid PVC) of pipe Series 4 of DIN 8062 or with threaded pipes of other materials and which meet the requirements of DIN 8063 Part 5.