Filter tube for placing in a borehole and method for manufacturing the filter tube

摘要

A filter pipe for inserting into a borehole comprises a support pipe (10) with liquid openings (12) and a porous filter layer (11) arranged on the outer side. The filter layer is made of a sintered plastic material whose pore diameter is smaller on the outer side of the filter layer than on the inner side bordering the support pipe. An Independent claim is also included for the production of the filter pipe comprising melting a lose charge of a sinterable granulate-like or powder-like plastic material to form a filter layer sintered to the support tube in a heating device and cooling after reaching a porous melt or sinter composite. Short term temperature elevation occurs at the end of the heat treatment to heat the outer surface layer of the plastic material.