In addition to the wear of the outer layer of steel wire, the lifting sling is mainly broken due to metal fatigue caused by repeated bending when bypassing the hook and the object to be lifted. Therefore, the ratio of the diameter of the hook or the object to be lifted to the diameter of the lifting sling is an important factor in determining the service life of the lifting sling. factor.
When one of the following situations occurs, the lifting sling should be stopped or repaired, replaced, or scrapped.
1. Irregular distribution of damage: within the length of 6 times the diameter of the lifting sling, the total number of broken wires is more than 5% of the total number of lifting sling wires;
2. Broken wires can be seen locally in the lifting sling: there are more than three broken wires gathered together;
3. There is a collection of broken wires on the surface of the cable eye, or the broken wires are concentrated in the metal sleeve, near the splicing point, and in the splicing connection strands;
4. The lifting sling is severely worn: the diameter of the lifting sling is measured at any position, and the size is less than 90% of the original nominal diameter;
5. The lifting sling is severely corroded: the flexibility is reduced, and the surface is rough. The diameter of the lifting sling is measured at the corroded part, and the size has not reached 93% of the original nominal diameter;
5. Lifting sling distortion, crushing, core damage or lifting sling flattening exceeds 20% of the original nominal diameter due to knotting, twisting, and extrusion;
6. Thermal damage of lifting sling: The strength of the lifting sling is reduced due to the burning of the lifting sling, the scalding of the molten metal caused by the electrified arc, or the long-term exposure and high-temperature environment;
7. The plug joint is severely squeezed, worn, or damaged by the metal sleeve (such as cracks, severe deformation, corrosion), or the diameter is reduced to 95% of the original nominal diameter;
8. The metal sleeve or the plug-in part of the fixed connection of the rope end slides out.