SA387 GR.22 steel plate is one kind Chromium-Molybdenum alloy used for welded pressure vessels and boilers designed for elevated temperature service in specification ASME SA 387/SA 387M.SA387 GR.22 cl1 steel plate and SA387 GR.22 cl2 steel plate owned the same chemical composition as Chromium 2.0 to 2.5 % and Molybdenum 0.9 to 1.1 % in heat analysis,the main different between these two classes,SA387 GR.22 cl1 steel plate requires minimum yield strenth 205 Mpa and tensile strength within 415-585 Mpa,however SA387 GR.22 cl2 steel plate requires minimum yield strenth 310 Mpa and tensile strength within 515-690 Mpa.So SA387GR22CL2 is better when used in high strength surroudings.

SA387 GR.22 cl1 steel plate and SA387 GR.22 cl2 steel plate shall be thermally treated either by annealing, normalizing and tempering,or,when permitted by the purchaser,accelerated cooling from the austenitizing temperature by air blasting or liquid quenching, followed by tempering.and minimum tempering temperature shall be above 675 degree centigrade.