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Causes and prevention of crane hook falling accidents

2025-07-30 05:43:35

crane hook detachment is a common cause of serious safety accidents, potentially resulting in casualties, equipment damage, and production disruptions. The following is an analysis of the root causes of these accidents , typical cases , and systematic prevention strategies .

1. Six main reasons for hook falling off

1.  Failure of the anti-unhooking device

  • Typical scenario : The spring lock is broken, deformed or rusted, making it impossible to close.

  • Data : Accounts for 40% of fall accidents (US OSHA statistics).

  • Case : At a construction site, the locking spring failed, causing the sling to slip and damage the truck.

2.  Sling installation error

  • Error Type :

    • The sling is not embedded in the base of the hook (hanging on the tip or side of the hook).

    • The cross-entanglement of multiple slings results in uneven force.

  • Consequences : Sling slippage or hook deformation.

3.  Overload or oblique pull

  • Mechanical influence :

    • Overload → plastic deformation of the hook → expansion of the hook mouth.

    • The horizontal component of the force causes the sling to slip (the risk increases when the angle is greater than 60°).

4.  Hook/sling wear exceeds standard

  • Scrap standards :

    • The hook width is worn more than 10% of the original size (GB 6067.1).

    • Sling diameter wear > 7% (ISO 4309).

5.  Failure of connecting components

  • Frequently Asked Questions :

    • Threaded hook nut is loose (not torqued).

    • The pin is broken (material does not meet the standards or fatigue).

6.  Human error

  • Typical behavior :

    • Lifting without checking the lock status.

    • Unclear command signals lead to erroneous operations.

2. 8 key measures to prevent shedding

1.  Mandatory use of anti-unhooking device

  • standard :

    • The anti-pullout force after the lock is closed is ≥10% of the rated load (ISO 2415).

    • Check the spring elasticity and closing status daily.

2.  Standardize the installation of slings

  • Correct operation :

    • The sling must be placed at the center of the hook base (not the hook tip).

    • The included angle of multiple slings is ≤60°, and a balance beam is used to distribute the load.

3.  Strict load management

  • Technical means :

    • Install a torque limiter (automatically cuts off power in case of overload).

    • The weight label of the hanging object is visualized (such as scanning the QR code for verification).

4.  Regular inspection and scrapping

  • Testing frequency :

    project cycle method
    Hook wear weekly Caliper measurement
    Crack inspection per month Magnetic particle testing (MT)
    Anti-unhooking function test daily Manual opening and closing 3 times

5.  Strengthening of connecting parts

  • Threaded hook :

    • Apply thread locker (such as Loctite 243).

    • Use a locknut (such as a Nord-Lock washer).

  • Pin :

    • The material is not less than 35CrMo, and the hardness is HRC 30-35.

6.  Operation training and supervision

  • Training focus :

    • The sling is correctly attached (simulated VR training).

    • Real-time identification and handling of cable-stayed/overloaded.

  • Supervision system :

    • High-risk operations require “double confirmation” (operator + commander).

7.  Environmental adaptability design

  • Corrosive environment :

    • Use 316 stainless steel hook or hot-dip galvanized (thickness ≥ 80μm).

  • Low temperature environment :

    • Material impact energy ≥ 27J (-20℃).

8.  Intelligent monitoring technology

  • IoT Solutions :

    • Strain sensors monitor load distribution in real time.

    • Camera AI identifies sling installation errors (such as Huawei Cloud EI algorithm).

III. Typical Accident Cases and Lessons

Case 1: Rusted lock caused chemical tank to fall

  • Process : The anti-unhooking lock was stuck due to acid mist corrosion and the lifting was carried out in an unclosed state.

  • Consequences : The tank fell and leaked, and production was suspended for 15 days.

  • Lesson : Corrosion-resistant locks (such as Hastelloy) must be used in chemical environments.

Case 2: The cable-stayed cable unhooked and smashed through the factory building

  • Process : The rope was not reeled in when the boom was rotating, and the sling slipped from the hook.

  • Consequences : 3 tons of steel components penetrated the roof and 1 person died.

  • Lesson : Install an “anti-sway system” + speed limit control.

4. Industry Best Practices

industry Special risks Targeted measures
port Salt spray corrosion + high frequency use Monthly replacement of locks + cathodic protection
metallurgy High temperature oxidation Heat-resistant hook + infrared temperature monitoring
Wind power Risk of falling from height Double lock design + drone inspection

V. Conclusion

Core principles of anti-falling :

  1. Reliable hardware : anti-unhooking device + regular inspection.

  2. Operation specifications : Overloading and slanting are strictly prohibited, and the equipment must be hung correctly.

  3. Technology empowerment : Intelligent monitoring replaces manual inspection of blind spots.

Warning :

"Once it falls off, it costs a lifetime!"
- The cost of all preventive measures is far less than the loss caused by accidents!

Crane hook detachment is a common cause of serious safety accidents, potentially resulting in casualties, equipment damage, and production disruptions. The following is an analysis of the root causes of these accidents , typical cases , and systematic prevention strategies .

1. Six main reasons for hook falling off

1.  Failure of the anti-unhooking device

  • Typical scenario : The spring lock is broken, deformed or rusted, making it impossible to close.

  • Data : Accounts for 40% of fall accidents (US OSHA statistics).

  • Case : At a construction site, the locking spring failed, causing the sling to slip and damage the truck.

2.  Sling installation error

  • Error Type :

    • The sling is not embedded in the base of the hook (hanging on the tip or side of the hook).

    • The cross-entanglement of multiple slings results in uneven force.

  • Consequences : Sling slippage or hook deformation.

3.  Overload or oblique pull

  • Mechanical influence :

    • Overload → plastic deformation of the hook → expansion of the hook mouth.

    • The horizontal component of the force causes the sling to slip (the risk increases when the angle is greater than 60°).

4.  Hook/sling wear exceeds standard

  • Scrap standards :

    • The hook width is worn more than 10% of the original size (GB 6067.1).

    • Sling diameter wear > 7% (ISO 4309).

5.  Failure of connecting components

  • Frequently Asked Questions :

    • Threaded hook nut is loose (not torqued).

    • The pin is broken (material does not meet the standards or fatigue).

6.  Human error

  • Typical behavior :

    • Lifting without checking the lock status.

    • Unclear command signals lead to erroneous operations.

2. 8 key measures to prevent shedding

1.  Mandatory use of anti-unhooking device

  • standard :

    • The anti-pullout force after the lock is closed is ≥10% of the rated load (ISO 2415).

    • Check the spring elasticity and closing status daily.

2.  Standardize the installation of slings

  • Correct operation :

    • The sling must be placed at the center of the hook base (not the hook tip).

    • The included angle of multiple slings is ≤60°, and a balance beam is used to distribute the load.

3.  Strict load management

  • Technical means :

    • Install a torque limiter (automatically cuts off power in case of overload).

    • The weight label of the hanging object is visualized (such as scanning the QR code for verification).

4.  Regular inspection and scrapping

  • Testing frequency :

    project cycle method
    Hook wear weekly Caliper measurement
    Crack inspection per month Magnetic particle testing (MT)
    Anti-unhooking function test daily Manual opening and closing 3 times

5.  Strengthening of connecting parts

  • Threaded hook :

    • Apply thread locker (such as Loctite 243).

    • Use a locknut (such as a Nord-Lock washer).

  • Pin :

    • The material is not less than 35CrMo, and the hardness is HRC 30-35.

6.  Operation training and supervision

  • Training focus :

    • The sling is correctly attached (simulated VR training).

    • Real-time identification and handling of cable-stayed/overloaded.

  • Supervision system :

    • High-risk operations require “double confirmation” (operator + commander).

7.  Environmental adaptability design

  • Corrosive environment :

    • Use 316 stainless steel hook or hot-dip galvanized (thickness ≥ 80μm).

  • Low temperature environment :

    • Material impact energy ≥ 27J (-20℃).

8.  Intelligent monitoring technology

  • IoT Solutions :

    • Strain sensors monitor load distribution in real time.

    • Camera AI identifies sling installation errors (such as Huawei Cloud EI algorithm).

III. Typical Accident Cases and Lessons

Case 1: Rusted lock caused chemical tank to fall

  • Process : The anti-unhooking lock was stuck due to acid mist corrosion and the lifting was carried out in an unclosed state.

  • Consequences : The tank fell and leaked, and production was suspended for 15 days.

  • Lesson : Corrosion-resistant locks (such as Hastelloy) must be used in chemical environments.

Case 2: The cable-stayed cable unhooked and smashed through the factory building

  • Process : The rope was not reeled in when the boom was rotating, and the sling slipped from the hook.

  • Consequences : 3 tons of steel components penetrated the roof and 1 person died.

  • Lesson : Install an “anti-sway system” + speed limit control.

4. Industry Best Practices

industry Special risks Targeted measures
port Salt spray corrosion + high frequency use Monthly replacement of locks + cathodic protection
metallurgy High temperature oxidation Heat-resistant hook + infrared temperature monitoring
Wind power Risk of falling from height Double lock design + drone inspection

V. Conclusion

Core principles of anti-falling :

  1. Reliable hardware : anti-unhooking device + regular inspection.

  2. Operation specifications : Overloading and slanting are strictly prohibited, and the equipment must be hung correctly.

  3. Technology empowerment : Intelligent monitoring replaces manual inspection of blind spots.

Warning :

"Once it falls off, it costs a lifetime!"
- The cost of all preventive measures is far less than the loss caused by accidents!

Crane hook detachment is a common cause of serious safety accidents, potentially resulting in casualties, equipment damage, and production disruptions. The following is an analysis of the root causes of these accidents , typical cases , and systematic prevention strategies .

1. Six main reasons for hook falling off

1.  Failure of the anti-unhooking device

  • Typical scenario : The spring lock is broken, deformed or rusted, making it impossible to close.

  • Data : Accounts for 40% of fall accidents (US OSHA statistics).

  • Case : At a construction site, the locking spring failed, causing the sling to slip and damage the truck.

2.  Sling installation error

  • Error Type :

    • The sling is not embedded in the base of the hook (hanging on the tip or side of the hook).

    • The cross-entanglement of multiple slings results in uneven force.

  • Consequences : Sling slippage or hook deformation.

3.  Overload or oblique pull

  • Mechanical influence :

    • Overload → plastic deformation of the hook → expansion of the hook mouth.

    • The horizontal component of the force causes the sling to slip (the risk increases when the angle is greater than 60°).

4.  Hook/sling wear exceeds standard

  • Scrap standards :

    • The hook width is worn more than 10% of the original size (GB 6067.1).

    • Sling diameter wear > 7% (ISO 4309).

5.  Failure of connecting components

  • Frequently Asked Questions :

    • Threaded hook nut is loose (not torqued).

    • The pin is broken (material does not meet the standards or fatigue).

6.  Human error

  • Typical behavior :

    • Lifting without checking the lock status.

    • Unclear command signals lead to erroneous operations.

2. 8 key measures to prevent shedding

1.  Mandatory use of anti-unhooking device

  • standard :

    • The anti-pullout force after the lock is closed is ≥10% of the rated load (ISO 2415).

    • Check the spring elasticity and closing status daily.

2.  Standardize the installation of slings

  • Correct operation :

    • The sling must be placed at the center of the hook base (not the hook tip).

    • The included angle of multiple slings is ≤60°, and a balance beam is used to distribute the load.

3.  Strict load management

  • Technical means :

    • Install a torque limiter (automatically cuts off power in case of overload).

    • The weight label of the hanging object is visualized (such as scanning the QR code for verification).

4.  Regular inspection and scrapping

  • Testing frequency :

    project cycle method
    Hook wear weekly Caliper measurement
    Crack inspection per month Magnetic particle testing (MT)
    Anti-unhooking function test daily Manual opening and closing 3 times

5.  Strengthening of connecting parts

  • Threaded hook :

    • Apply thread locker (such as Loctite 243).

    • Use a locknut (such as a Nord-Lock washer).

  • Pin :

    • The material is not less than 35CrMo, and the hardness is HRC 30-35.

6.  Operation training and supervision

  • Training focus :

    • The sling is correctly attached (simulated VR training).

    • Real-time identification and handling of cable-stayed/overloaded.

  • Supervision system :

    • High-risk operations require “double confirmation” (operator + commander).

7.  Environmental adaptability design

  • Corrosive environment :

    • Use 316 stainless steel hook or hot-dip galvanized (thickness ≥ 80μm).

  • Low temperature environment :

    • Material impact energy ≥ 27J (-20℃).

8.  Intelligent monitoring technology

  • IoT Solutions :

    • Strain sensors monitor load distribution in real time.

    • Camera AI identifies sling installation errors (such as Huawei Cloud EI algorithm).

III. Typical Accident Cases and Lessons

Case 1: Rusted lock caused chemical tank to fall

  • Process : The anti-unhooking lock was stuck due to acid mist corrosion and the lifting was carried out in an unclosed state.

  • Consequences : The tank fell and leaked, and production was suspended for 15 days.

  • Lesson : Corrosion-resistant locks (such as Hastelloy) must be used in chemical environments.

Case 2: The cable-stayed cable unhooked and smashed through the factory building

  • Process : The rope was not reeled in when the boom was rotating, and the sling slipped from the hook.

  • Consequences : 3 tons of steel components penetrated the roof and 1 person died.

  • Lesson : Install an “anti-sway system” + speed limit control.

4. Industry Best Practices

industry Special risks Targeted measures
port Salt spray corrosion + high frequency use Monthly replacement of locks + cathodic protection
metallurgy High temperature oxidation Heat-resistant hook + infrared temperature monitoring
Wind power Risk of falling from height Double lock design + drone inspection

V. Conclusion

Core principles of anti-falling :

  1. Reliable hardware : anti-unhooking device + regular inspection.

  2. Operation specifications : Overloading and slanting are strictly prohibited, and the equipment must be hung correctly.

  3. Technology empowerment : Intelligent monitoring replaces manual inspection of blind spots.

Warning :

"Once it falls off, it costs a lifetime!"
- The cost of all preventive measures is far less than the loss caused by accidents!

Pre: Repair solution for excessive wear of crane hook
Next: Case of accident caused by improper operation of crane hook

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