When polypropylene hot-water pipes are die drawn, they gain spectacular increases in hydrostatic pressure resistance and impact strength.
When polypropylene hot-water pipes are die drawn, they gain spectacular increases in hydrostatic pressure resistance and impact strength. This was demonstrated through R&D by Leeds University in England in cooperation with SABIC and DSM Resolve in the Netherlands. They reported the results at the SPE ANTEC meeting in Boston in May. The researchers stretched thick tubular billets with an initial ID of 6 mm and OD of 26 mm into biaxially oriented pipe with final dimensions of 28 mm ID and 32 mm OD. Oriented tube samples survived 16 MPa (2320 psi) of hydrostatic pressure at 68 F for more than 2000 hr, whereas unoriented pipes last 20 to 50 hr under those conditions. At 3.5 MPa (508 psi) and 203 F, the oriented pipe’s lifetime went up to 2300 hr, whereas the industry requirement is only 100 hr. Tel: +44 (113) 343 3808 • e-mail: i.m.ward@leeds.ac.uk