| 摘要 |
The present invention describes a seamless steel tube for work-over risers comprising in weight per cent, carbon 0.23-0.29, manganese 0.45-0.65, silicon 0.15-0.35, chromium 0.90-1.20, molybdenum 0.70- 0.90, nickel 0.20 max, nitrogen 0.010 max, boron 0.0010-0.0030, aluminum 0.010-0.045, sulfur 0.005 max, phosphorus 0.015 max, titanium 0.005-0.030, niobium 0.020-0.035, copper 0.15 max, arsenic 0.020 max, calcium 0.0040 max, tin 0.020 max, hydrogen 2.4 ppm max, the rest are iron and inevitable impurities, consisting of a geometry in which ends of the tube have an increased wall thickness and outer diameter and having a yield strength of at least of 620 MPa (90 ksi) throughout the whole length of a tube body and in tube ends. The present invention also describes methods for manufacturing a seamless steel tube for work-over risers having a yield strength at least of 620 MPa (90ksi) both in a tube body and in tube ends. |
