Hardware machining repair welding requirements

　　 1. Defects must be thoroughly removed before welding, and the groove surface should be repaired smoothly and without sharp corners;

　　2. During surfacing welding on the surface of steel castings, the overlap between the weld beads shall not be less than one-third of the width of the weld bead, the weld meat shall be full, and the weld surface shall be free of burns, cracks and obvious nodules. The welding seam has beautiful appearance, no biting meat, slagging, pores, cracks, splashing and other defects, and the welding wave is uniform;

　　3. According to the defects of the steel castings, the defects in the welding zone shall be removed by shoveling, grinding, carbon arc gouging, gas cutting or mechanical processing;

　　4. During repair welding, the welding rod should not make excessive lateral swing;

　　5. The sticky sand, oil, water, rust and other dirt within 20mm around the groove of the welding area must be thoroughly cleaned up;

　　6. When conditions permit, perform welding work in a horizontal position as much as possible;

　　7. During the whole welding process, the temperature of the preheating zone of the steel casting shall not be lower than 350°C; v