Patent ID: 6282933
Filing Date: 2001-09-04
Classification: C21D,F16L

Abstract:
A method of manufacturing a metal carcass for use in a flexible pipe or umbilical, which pipe or umbilical includes a pressure vault outward of the carcass, the method comprising:shaping a metal strip and then helically winding the strip to form a metal carcass, wherein the metal strip would have a given strength, if the metal strip were in a cardioid mode while inside the pressure vault and without work-hardening of the strip;the method further comprising work-hardening the metal strip, prior to shaping the strip and prior to winding the strip to form a carcass, for giving the strip elongation at rupture of at least 15% and such that the metal carcass formed by helically winding the work-hardened metal strip has in cardioid mode and while inside the pressure vault a collapse strength which is at least 15% higher than the given collapse strength.