The surface of the groove shall not have defects such as cracks, delamination and inclusions. The surface of the groove with a lower tensile strength >540 MPa and the surface of the Cr-Mo low alloy steel plate is flame-polished, smoothed with a grinding wheel, and subjected to magnetic powder or permeation detection on the machined surface. Oxide, oil, slag, dust, iron powder and other harmful impurities in the range of 20 mm on both sides of the groove and its parent metal shall be removed before welding. The amount of misalignment b of the opposite side of the panel shall not be greater than 10% of the thickness δ of the steel, and not more than 1.5 mm. The amount of misalignment b of the spliced composite steel plate is not more than 30% of the thickness of the composite layer of the steel sheet, and is not more than 1.0 mm. The welding procedure qualification before tailor welding shall be carried out in accordance with JB 4708-2000.

The welding process qualification lecture, welding procedure specification, welding record and welder's identification mark retention period shall be in accordance with the relevant delimitation of GB 150-1998 or JB 4732-1995 according to the design scale adopted by the head.

The welded surface of the inner surface of the disc-shaped and spherical crown-shaped head formed by the first panel and the outer surface of the spherical-shaped head are welded together, and the surplus height of seam should be polished to be flush with the base material before forming. Before the forming of the conical head, the weld height of the inner and outer surfaces of the transition department shall be polished to be flush with the base material. The surplus height of seam without grinding shall be in accordance with the relevant specifications of GB150-1998 or JB 4732-1995 according to the actual scale adopted by the head. The surface of the joint shall not have cracks, undercuts, pores, craters and Splash. The repair of the spliced welded joints shall be in accordance with the relevant design of GB 150-1998 or JB 4732-1995 according to the design scale adopted by the head. After the blank is cut, the defects affecting the forming quality of the head shall be polished.

Jiuzhou head mainly produces head, which can be pressed as a whole or divided into pieces to complete various materials of head for boiler and pressure vessel.