-
公开(公告)号:US06720048B2
公开(公告)日:2004-04-13
申请号:US10049621
申请日:2002-02-22
IPC分类号: F16L912
CPC分类号: F16L9/127 , F16L11/06 , Y10S138/07 , Y10T428/1352 , Y10T428/1386 , Y10T428/139
摘要: The pipe of the present invention comprises an ethylene base polymer comprising ethylene and an &agr;-olefin having 3 to 20 carbon atoms, wherein (A) a maximum value of the residual stress is 0.13 MPa or less; (B) the crystallinity is 0.630 to 0.850; (C) a gradient of the crystallinity against a thickness of the pipe is 0.465 or less; and (D) the pipe has a thickness of 5 to 50 mm. It is excellent in a durability, a rigidity and an impact resistance and suited to uses for large diameter pipes receiving a high internal pressure.