1. Chains often used for lifting molten metal should be annealed regularly 2. The suspension chain should be used before the use of a single limit load of 2 times the static load test hanging for 10 minutes without breaking or obvious elongation of individual chain link is qualified. 3. The difference between the effective length of the longest and the shortest branches of a multi-branch chain when measured by the tensile force of a 1/5 limit working load should not exceed 6 mm when the length is less than 2 m and 3 mm per 1 m when the length is more than 2 m. Four. When working in high temperature environment, the maximum working load of the spreader should meet the requirements. 5. S (6) , T (8) class suspension chain should not be used in acidic solution, acidic steam. When the M (4) class chain is used in acid medium, the ultimate working load of the chain should not be greater than 50% of the original limit working load. 6. The chain should be checked thoroughly before use. When preparing for lifting, the chain should be straight and not twisted, knotted or bent. Seven. Before using the chain binding type, it is important to check the wear condition of the hook in the sliding area of the chain. 8 when multiple chains are connected through the load lugs, the angle between the branches should not exceed 60 ° (30 ° with the angle between the vertical line) .