Bulletin / Circular by Welding Research Council, Inc., 1988

The subcommittee on Pressure Vessel Steels of JPVRC published a study report in 1981 titled "Application of Controlled Rolled Steel Plates for Tank and Pressure Vessel." The data in this report were primarily obtained from line pipe steels with high strength and toughness, based on Nb or Nb-V alloy systems. While the base plate exhibited superior toughness, the toughness of the welded joints was not always sufficient for low-temperature service pressure vessels. Toughness testing was required at temperatures not lower than -20°C.

Over the past five years, low-temperature service steel plates have faced new challenges. The design and fabrication of Arctic offshore structures, icebreaking ships, and pressure vessels for liquefied gas have increased the demand for steel plates with a tensile strength of 500 MPa. These steels needed high toughness not only in the base plate but also in the welded joints, along with compatibility for high heat input welding and preheating-free welding. During this period, both Japanese steel manufacturers and fabricators developed new processes. The steelmakers introduced the Thermo-Mechanical Control Process (TMCP), incorporating accelerated cooling techniques in plate rolling. They have also developed new low-temperature steels meeting these demands. Fabricators, on the other hand, have implemented highly efficient welding technologies. Extensive collaboration between these groups has resulted in a wealth of valuable data on the practical use of these steels and welding methods.

Currently, TMCP has been approved for structural steel production by major ship classification societies, JIS, and ASTM. JIS G 3115 and G 3126 define standard specifications for steel plates used in pressure vessels for intermediate and low-temperature service. ASTM A 841 is the standard for TMCP-produced pressure vessel steel plates and is under discussion as API standard 2W. The specifications and requirements of JIS and ASTM standards are summarized in Table 1.

The new initiative of the JPVRC Pressure Vessel Steels Subcommittee aims to review TMCP and provide unified insights on TMCP steels for structural applications in low-temperature environments. This report compiles the latest data from Japanese steel manufacturers and fabricators on TMCP steels.

#PressureVesselSteels | #TMCP | #LowTemperatureSteels | #WeldingTechnology | #StructuralSteels

For a detailed review, you can access the study here.