What are the standards for scrapping crane hooks?
The scrapping standard of crane hooks is an important basis for ensuring operational safety and must be strictly implemented in accordance with national and industry standards (such as GB/T 10051 "crane hooks" , ISO 2415 or FEM 1.001 ). The following are the main scrapping conditions:
1. Appearance defects
-
Cracks : Any cracks visible to the naked eye
(confirmed by magnetic particle or penetrant testing) in any part (hook body, thread, neck) must be scrapped immediately. -
Plastic deformation :
The hook mouth (such as the opening exceeds 10% of the original size ) or the hook body is permanently bent or twisted (such as the hook tip twists more than 10° ). -
Wear :
-
The dangerous section of the hook mouth (such as the AA section shown in the figure) is worn to 5% (high-risk occasions) or 10% (general occasions) of the original size.
-
The anti-unhooking device (such as spring lock plate) is worn, fails or deformed.
-
2. Hook handle and thread damage
-
Thread damage :
Thread slippage and rust lead to excessive fit clearance, or insufficient effective screwing length (such as less than 80% of the design value ). -
Hook handle deformation :
The hook handle (the part connected to the sling) is bent, flattened or corroded and thinned by more than 5% .
3. Deterioration of material properties
-
Overload history :
The hook has been subjected to an impact load exceeding 110% of the rated load (need to check for hidden damage). -
Heat treatment failure : material annealing (hardness decreases by more than 15% ) or metallographic structure deterioration (such as grain coarsening)
due to high temperature operation .
4. Corrosion and rust
-
Uniform corrosion : The cross-sectional area of the dangerous section is reduced by more than 10%
due to rust . -
Pitting or stress corrosion :
Corrosion depth exceeds 1mm (especially in high humidity and chemical environments).
5. Other failure characteristics
-
Hook tail bearing wear :
The bearing clearance of the rotating hook is too large, causing shaking and affecting positioning accuracy. -
Welding repair traces : Welding repair is prohibited
for the hook . If any traces of repair welding or thermal cutting are found, the hook shall be scrapped directly. -
Aging :
If the product is used for more than 15 years (or the life span specified by the manufacturer), it is mandatory to inspect it. Even if there are no visible defects, it may fail due to fatigue.
Detection Methods
-
Magnetic particle testing (MT) : detects surface cracks.
-
Ultrasonic thickness testing (UT) : assesses corrosion thinning.
-
Hardness test : Verify whether the material has degraded.
Precautions
-
Regular inspection : daily inspection (visual) + annual professional inspection (including non-destructive testing).
-
Record retention : Scrapped hooks should be destroyed (such as cutting) to avoid misuse.
For example : The original hook width of a certain hook is 50mm, but after actual wear it reaches 55mm (more than 10%), or the diameter of the dangerous section wears from 30mm to 27mm (a decrease of 10%), both of which need to be scrapped.
Safety Tips: Even if the vehicle does not meet the scrap standards, it should be stopped and inspected if there are safety hazards (such as abnormal noises or jamming).
The scrapping standard of crane hooks is an important basis for ensuring operational safety and must be strictly implemented in accordance with national and industry standards (such as GB/T 10051 "Crane Hooks" , ISO 2415 or FEM 1.001 ). The following are the main scrapping conditions:
1. Appearance defects
-
Cracks : Any cracks visible to the naked eye
(confirmed by magnetic particle or penetrant testing) in any part (hook body, thread, neck) must be scrapped immediately. -
Plastic deformation :
The hook mouth (such as the opening exceeds 10% of the original size ) or the hook body is permanently bent or twisted (such as the hook tip twists more than 10° ). -
Wear :
-
The dangerous section of the hook mouth (such as the AA section shown in the figure) is worn to 5% (high-risk occasions) or 10% (general occasions) of the original size.
-
The anti-unhooking device (such as spring lock plate) is worn, fails or deformed.
-
2. Hook handle and thread damage
-
Thread damage :
Thread slippage and rust lead to excessive fit clearance, or insufficient effective screwing length (such as less than 80% of the design value ). -
Hook handle deformation :
The hook handle (the part connected to the sling) is bent, flattened or corroded and thinned by more than 5% .
3. Deterioration of material properties
-
Overload history :
The hook has been subjected to an impact load exceeding 110% of the rated load (need to check for hidden damage). -
Heat treatment failure : material annealing (hardness decreases by more than 15% ) or metallographic structure deterioration (such as grain coarsening)
due to high temperature operation .
4. Corrosion and rust
-
Uniform corrosion : The cross-sectional area of the dangerous section is reduced by more than 10%
due to rust . -
Pitting or stress corrosion :
Corrosion depth exceeds 1mm (especially in high humidity and chemical environments).
5. Other failure characteristics
-
Hook tail bearing wear :
The bearing clearance of the rotating hook is too large, causing shaking and affecting positioning accuracy. -
Welding repair traces : Welding repair is prohibited
for the hook . If any traces of repair welding or thermal cutting are found, the hook shall be scrapped directly. -
Aging :
If the product is used for more than 15 years (or the life span specified by the manufacturer), it is mandatory to inspect it. Even if there are no visible defects, it may fail due to fatigue.
Detection Methods
-
Magnetic particle testing (MT) : detects surface cracks.
-
Ultrasonic thickness testing (UT) : assesses corrosion thinning.
-
Hardness test : Verify whether the material has degraded.
Precautions
-
Regular inspection : daily inspection (visual) + annual professional inspection (including non-destructive testing).
-
Record retention : Scrapped hooks should be destroyed (such as cutting) to avoid misuse.
For example : The original hook width of a certain hook is 50mm, but after actual wear it reaches 55mm (more than 10%), or the diameter of the dangerous section wears from 30mm to 27mm (a decrease of 10%), both of which need to be scrapped.
Safety Tips: Even if the vehicle does not meet the scrap standards, it should be stopped and inspected if there are safety hazards (such as abnormal noises or jamming).
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