News

1. Analysis of typical overload accident cases

Case 1: A major accident at a shipyard in 2022

• Accident : A 50t-class hook was used to lift a 68t section (36% overload), and the hook neck broke, resulting in 3 deaths.

• Direct loss : Equipment damage of RMB 2.8 million, production suspension for 45 days

• Technical Analysis :

  • The actual stress reaches 689MPa (34CrMo material yield strength 630MPa)

  • The safety factor dropped from 4.0 to 1.85

Case 2: Wind turbine tower installation accident

• Features : Dynamic overload (impact coefficient reaches 1.8 during rapid acceleration)

• Consequence : hook opening deformed 12mm (exceeding 10% scrap standard)

2. Six key issues exposed by the accident

1. Design flaws

   • No multiple protection system (only single torque limiter)

   • Insufficient safety factor margin (EU standard requires ≥5)

2. Managing vulnerabilities

   • The overload approval process is ineffective (82% of accidents involve illegal approval)

   • Missing lifting equipment files (35% of accident hooks have no inspection records)

3. Technical shortcomings

   • The error of traditional mechanical torquer is >±8%

   • Lack of real-time stress monitoring methods

4. Human Factors

   • Signal command misjudgment accounts for 67%

   • The coverage rate of emergency operation training is only 41%.

5. Environmental risks

   • Operations continued even when wind speed was >12m/s (accounting for 93% of wind disasters)

   • -20℃ low temperature without switching material

6. Regulatory failure

   • Third-party testing is a formality (23% of reports are falsified)

3. Technical Improvement Plan (2023 New Version)

1. Triple protection system upgrade

2. Intelligent monitoring system

• 5G+Fiber Optic Sensor Network :

  • Real-time display of hook stress cloud map (refresh rate 50Hz)

  • Automatically trigger three-level braking when overloaded:

    python

    if stress > 0.8σy: # Yield strength 80% warning
        alert()
        reduce_speed(50%)
    elif stress > σy: # super yield strength
        emergency_stop()

3. Material Upgrade Path

• Traditional material: 34CrMo (σy=630MPa)

• New materials:

  • Ultra-high strength steel: MSB-900 (σy=900MPa, cost +35%)

  • Composite materials: carbon fiber reinforced aluminum matrix (40% weight reduction)

IV. Management Improvement Measures

1. Full life cycle management system

2. Personnel Capability Matrix

3. Digital Twin Preview

• Simulation before lifting:

  • Dynamic loads at different wind speeds

  • Stress analysis of emergency braking conditions

5. Cost-Benefit Analysis

VI. Suggestions for Improving Industry Standards

1. Load spectrum normalization :

   • Add dynamic impact coefficient (not covered by current GB/T 3811)

   • Clarify the correction formula for composite working conditions:

     text

     F_dynamic = K1·K2·F_static
     (K1: acceleration coefficient, K2: wind load coefficient)

2. Mandatory requirements for testing technology :

   • Hooks above 100t must be equipped with online monitoring

   • Annual inspections must include TOFD testing

Conclusion

Overload accident prevention and control requires the construction of a "technology-management-standard" trinity system:

1. Short term (6 months): Complete the protection system transformation

2. Medium term (2 years): Achieve digital twin coverage across all industries

3. Long-term : Promote smart hooks to become legal standards

A bitter lesson : Every 1 yuan invested in prevention can avoid 87 yuan in accident losses (calculated based on the LEC method)