Abstract: A method is disclosed for the production of extruded plastic products by using an extruder (1) which has an extruder hopper (2) which is supplied with a hot mixture obtained by discontinuous mixing of PVC powder and aditives in a hot mixing zone, with the supply of frictional heat, wherein a first amount of PVC powder is mixed with an excess of additives with the supply of frictional heat, after which the mixture thus obtained is homogenised in the same mixing zone with a supplementary amount of PVC powder, in such a way that the final mixture has the desired concentration of additives, after which the hot mixture obtained after homogenisation is fed directly to the extruder hopper (2). An installation for the production of plastic products by extrusion, comprising a discontinuously operating hot mixer is also disclosed, as well as said hot mixer (3).

Abstract: Electroweldable pipe sockets and fittings by forming a first tube being internally sized and cooled and on the outer side provided with a groove, having preferably a raised edge part, winding an electrical conductor in the groove, and the outer side of the first tube with electrical conductor is coated with plastics thereby maintaining the internal size of the first tube by internal cooling and sizing. In this continuous process the speeds of the first tube and of the continuous tube leaving the coating extrusion stage are equal. In the coating extrusion stage a negative pressure is maintained between the first tube and the coating to be applied.