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Crane troubleshooting (metal structure part)

Update time : 2020-09-17 Publisher:Dotrum

1. Fatigue cracks in the main beam web or cover
Failure reason: long-term overload use
Elimination method: If the crack is not larger than 0.1mm, it can be flattened with a grinding wheel. For larger cracks, small holes larger than φ8mm can be drilled at both ends of the crack, and then 60° grooves are made along both ends of the crack for welding repair . Reinforcement plate repair welding should be applied to the important stressed components to ensure their strength
2. Dewelding of each splicing weld of the main beam or welding of truss nodes
Causes of failure: (1) The original welding quality is poor, with welding defects (2) Long-term overload use (3) Improper welding process, resulting in excessive welding residual stress
Elimination methods: (1) Repair welding with high-quality welding rods (2) Overload use is strictly prohibited (3) Use reasonable welding processes
3. The main beam web has wave deformation
Causes of the failure: (1) Welding process is improper, and internal welding stress is generated. (2) Overloaded use makes the web partially unstable
Elimination methods: (1) Use flame correction to eliminate deformation and beat to eliminate internal stress (2) Overload use is strictly prohibited
4. Side bending deformation of main beam
Reasons for failure: (1) Improper welding process during manufacturing, caused by the superposition of internal welding stress and working stress (2) Improper transportation and storage
Elimination method: (1) Use flame correction method to heat the convex side of the main beam, and appropriately use top tools and pull tools
5. The main beam sinks and deforms
Causes of failure: (1) Structural stress of the main beam (2) Wave deformation of the web (3) Overload use (4) The influence of thermal effects (5) Improper storage, transportation and others
Elimination methods: (1) Use flame correction method, and use channel steel reinforcement along the lower cover of the main girder (2) Use prestress correction method, and the reinforcement method is prestressed tie rods.
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