Martensitic stainless steel seamless pipe for linepipe

A martensitic stainless steel seamless pipe for linepipe application, KL-HP12CR, has been developed with good weldability, mechanical properties and corrosion resistance. Weldability is improved by the reduction of both C and N content. C reduction is also effective to the improvement of CO2 corrosion resistance achieving the corrosion rate less than 0.127 mm/y under the CO2 environment at 160°C and 2.0 MPa. It can be applied under the H2S environment at pH4.0 and 0.001 MPa, since the resistance to sulfide stress cracking (SSC) is improved by Mo addition. The pipe has X80-grade strength and sufficient low temperature toughness for the practical use as a linepipe. Post weld heat treatment (PWHT) in a few minutes, the reduction of C content and addition of Ti are effective to prevent intergranular stress corrosion cracking (IGSCC) at the heat affected zone. Further application of the pipe is expected for the transportation of product fluid with corrosive gas such as CO2, as an economical material with low life cycle cost.