MANUFACTURE AND PROPERTIES OF 9 Cr STEEL LARGE DIAMETER PIPE.

9 Cr ferritic steels have been studied as an alternative material for high-pressure parts in fossil-fuel fired power plants. These parts include main steam pipe and header applications, for which 2. 25 Cr-1 Mo steel is currently being used. The increased chromium content of 9 Cr steels produces higher oxidation resistance than 2. 25 Cr-1 Mo steel, and the elevated temperature strengths of these steels are also high. Furthermore, these steels, compared with austenitic stainless steels, provide advantages in terms of cost reduction and reduction of the thermal stresses generated during field operation. This work confirmed that 9 Cr steels are applicable to large diameter heavy walled pipe. Effective procedures for manufacturing this pipe have also been established.