素素猫中国微合金化技术与含铌钢发展30周-of Evolution
High Strength Microalloyed Linepipe: Half a Century of Evolution 37
Examples of the chemical compositions of X-65 sour service linepipe produced with the new technology (circa 1995) are presented in Table 12.
Table 12: Chemical Composition of API Grade X-65 for Sour Service
Evolution of Linepipe Producers & Production
As stated earlier manufacturing technologies for all HSLA steels improved rapidly from 1970 onward often due to demands from the linepipe arena. The demands occurred regionally, first in Alaska and later in the North Sea, followed by the demand for massive volumes of 56” OD X-70 (K60) linepipe from the former Soviet Union from 1970 through 1992 at which point the market collapsed.
Middle East demands from Saudi Arabia, Oman, Iran etc were for sour service X-60 and X-65 grades. In North America Canadian gas transmission companies such as TCPL and West Coast Energy led the move to higher strength levels.
For example: X-70 Nb-Mo steel was adopted by TCPL in 1970 produced at that time by IPSCO from semi-killed ingot steel [59]. Nowadays the pipe is produced from fully-killed continuously cast very low carbon (0.035%) skelp [60].
