Load test shall be carried out for new hook, and the measured opening of hook mouth shall not exceed 0.25% of the original opening. During use, the hooks shall be frequently checked for cracks, serious deformation, corrosion and wear. The hook shall be tested once a year. During the test, the static test shall be carried out with 1.25 times of the allowable working load for 10min. The magnifier or other methods shall be used to check that there shall be no cracks, cracks and residual deformation.

The hook shall be free of defects that may affect the safe use performance; The hook defects shall not be repaired by welding; The surface of the hook shall be smooth and free of cracks, folds, acute angles, burrs, peeling, burning and other defects. Two suitable positions can be selected at the shortest distance of the hook opening to print signs that are not easy to wear, and the distance of the signs can be measured as the basis for detecting whether the opening degree changes during use.