The subcommittee on Pressure Vessel Steels of JPVRC summarized a study report, entitled Application of Controlled Rolled Steel Plates for Tank and Pressure Vessel in 1981.The data included in the report was primarily obtained from line pipe steel with high strength and high toughness whose alloy system was Nb or Nb-V.In contrast to its superior toughness in the base plate, the toughness in weldment was not always satisfactory for a low-temperature service pressure vessel.The toughness testing was required at a temperature not lower than -20C.Moreover, steel plate itself was not as heavy as used for many pressure vessel applications.