Steel Structure Reinforcement --the Order of Using Welding to Repair Cracks
1. Clean the surface of the crack on both sides of the crack from 80mm, till the metal surface exposes fairly clear;
2. Use carbon arc gouging, air shovel or grinding wheel to machine the crack edge out of the slope, straight to the end of the hole, the form of the groove should be according to the plate thickness and construction conditions, it is selected according to the requirements of the current "Basic Types and Dimensions of Weld Bevels for Gas Welding, Manual Arc Welding and Gas Protection";
3. Preheat the sides and end metal of the crack to 100 °C - 150 °C, and maintain this temperature during the welding process;
4. Welding with low hydrogen type electrode or ultra low hydrogen type electrode matched with steel;
5. As far as possible, use small direct welding rods to perform stepwise layered reverse welding and welding. After each welding line is welded, it is necessary to perform hammering;
6. Check the weld quality according to the design requirements;
7. For components subjected to dynamic loads, the surface of the components subjected to plugging shall be polished to be flush with the surface of the original component, and the line of grinding marks shall be substantially perpendicular to the direction of the tangential direction of the crack;
