Singlelayer and multilayer polyolefin foam pipes

Pipes for transporting crude oil or gas products, or for district heating applications, which are steel pipes coated with a single layer of a polyolefin foam, for insulation purposes, and for use in non- or low-pressure applications;

• or are multilayer polyolefin pipes for the transportation of hot or cold fluids, wherein at least one layer thereof is a polyolefin foam, the polyolefin foam layer of said pipes being produced by one of a coextrusion, injection molding, and blow molding process, wherein the polyolefin foam layer has a density of from 50 to 850 kg/m3, and the polyolefin of the polyolefin foam layer is a mixture of
• A) 5 to 80% by weight of a compound A, which is selected from the group consisting of modified propylene polymers with a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg, the modified propylene polymers having strain hardening behavior, and mixtures of these modified propylene polymers, and
• B) 20 to 95% by weight of a compound B which is selected from the group consisting of propylene homopolymers with a stereospecifity index >98% and a melt index of 0.05 to 10 g/10 min at 230° C./2.16 kg and copolymers from 80.0 to 99.9% by weight of propylene and 0.1 to 20.0% by weight of ethylene or α-olefins with 4 to 18 carbon atoms with a stereospecifity index of the propylene homopolymer matrix of >96% and a melt index of 0.1 to 10 g/10 min at 230° C./2.16 kg, and mixtures of said propylene homopolymers and/or copolymers,
• wherein the melt of the mixture of compounds A and B in the coextrusion or injection molding or blow molding foam process contains up to 12% by weight, based on the mixture of compounds A and B, of chemical blowing agents that split off gas, or hydrocarbons, halogenated hydrocarbons and/or gases as blowing agents.