Study on Key Process Parameters of the Local Post Weld Heat Treatment by Electric Heating for the Large Thick-Walled Pressure Vessel Cylinder Butt Weld

Abstract

The local post weld heat treatment for pressure vessel cylinder butt circumferential weld performed by resistance heating a shielded band around the entire circumference. The width of heated band must be large enough to ensure that the temperature of the weld, heat-effect zone and a portion of base metal adjacent to the weld should meet the requirement given in the standards. When the diameter of pressure vessel cylinder is enough large to allow the installation of heater and thermal insulation on the inner surface of wall, the circumferential butt weld heated simultaneously on interior and exterior surface of cylinder wall is more energy economical. However, GB/T 30583-2014 don’t provide the recommended width of heated band for the local post weld heat treatment performed by heating simultaneously on the inner and outer surface of cylindrical wall when the wall thickness is large than 50mm. So numerical simulation was carried out to study the effect of the width of heated band on the soak band temperature distribution when the local post weld heat treatment for cylinder pressure vessel with the thickness rang of 60mm∼100mm performed by heating simultaneously on interior and exterior surface in this paper. The results show that the widths of heated band should be not less than six times thickness when post weld heat treatment for cylinder pressure vessel butt welds whose thickness is 60mm∼70mm with a diameter of 2000 mm performed by heating simultaneously on interior and exterior surface and the widths of heated band should be not less than five times thickness when post weld heat treatment for cylinder pressure vessel butt welds whose thickness is 70mm∼100mm.