中国微合金化技术与含铌钢发展30周-of Evolution(14)

中国微合金化技术与含铌钢发展30周-of Evolution

34 中国含铌钢技术发展30周年国际研讨会论文集

The steels used for production of large diameter DSAW linepipe are processed on conventional plate mills [30, 47, 48], Steckel mill facilities [49], or heavy strip mills (for 24 inch diameter spiral seam linepipe), whereas skelp for HFERW linepipe is produced either on conventional hot strip mills or increasingly by direct conversion of thin (50-125 mm) slabs. Typical steel compositions for Grade X-80 linepipe produced on a conventional hot strip mill are presented in Table 8 [45-46].

Table 8: Chemical compositions of API Grade X-80 ERW linepipe.

Seamless product for use in linepipe and oil and gas riser systems is becoming available in strengths up to the 90-100 ksi level and is invariably produced by quenching and tempering. In recent years carbon contents have been reduced to below 0.10 percent to improve field weldability, to improve weld heat affected zone (HAZ) toughness and fatigue resistance, and to reduce HAZ hardness so as to improve SSC resistance.

Examples of the chemical compositions of seamless linepipe are presented Table 9 below

[52-54]:

Table 9:Chemical composition of API Grade X-80 Seamless linepipe. The aforementioned examples of linepipe steel compositions mainly relate to product required for low temperature or sweet (i.e. treated non-corrosive) gas service. However, many developments have occurred in regions producing gas containing H2S, CO2 and chlorides. Depending on the concentrations of each of the above, the moisture content and ease and feasibility of inhibition, the end user may elect to use either carbon steels or more highly alloyed corrosion resistant grades. Examples of modern sour service carbon steels used for production of DSAW linepipe for the Black Sea Pipeline are presented in Table 10 below

[56].