The invention relates to a polypropylene composition comprising a propylene homopolymer or propylene-ethylene copolymer having an ethylene content of at most (1.0) wt % based on the propylene-ethylene copolymer, wherein the amount of propylene homopolymer or propylene-ethylene copolymer is at least (98) wt %, for example at least (98.5) wt %, preferably at least (99) wt %, more preferably at least (99.5), for example at least (99.75) wt % based on the polypropylene composition, wherein the polypropylene composition has a melt flow rate in the range of (0.10) to less than (0.70) dg/min as measured according to ISO1133 (2.16 kg/230° C.), an Mw/Mn in the range from (7.0) to (13.0), wherein Mw stands for the weight average molecular weight and Mn stands for the number average weight, an Mz/Mn is in the range from (20) to (50), wherein Mz stands for the z-average molecular weight and wherein Mw, Mn and Mz are measured according to ASTM (D6474-12).