JT/T 421-2024 in English

Key points of standard update

Key technology upgrade analysis

Metal structure safety enhancement

Chapter 5 of the new standard clearly requires that the foundation flange must be connected with high-strength bolts, and its torque coefficient should be controlled in the range of 0.11~0.15. For the main load-bearing components, if the corrosion reaches 10% of the design thickness, it will be forced to be scrapped, and the safety margin is increased by 20% compared with the 2000 version.

Intelligent safety protection system

The newly added safety monitoring and management system in Chapter 9 requires real-time monitoring of 8 parameters such as lifting weight, amplitude, wind speed, etc., and the data storage period is not less than 30 working days. In case of system failure, the sound and light alarm must be triggered within 2 seconds.

Implementation Suggestions

1. Renovation of existing equipment: focus on checking the slewing bearing and brake systems to ensure compliance with the synchronous control requirements of Article 6.4
2. Acceptance of new equipment: conduct 125% static load test and 110% dynamic load test in accordance with the requirements of Chapter 11
3. Operation and maintenance management: establish a three-dimensional inspection system based on Chapter 13 (daily inspection/monthly inspection/annual inspection)

Background of standard evolution

This standard responds to the changes in the ISO 4306-2018 international standard. In view of the current situation of the increased operating intensity of fixed cranes in my country's ports (an average of 1.8 times that of the 2000 version), it has especially strengthened the following:

• Typhoon-resistant design (working wind speed increased to 20m/s)
• Steel structure fatigue life (number of cycles ≥ 2×10⁶)
• Intelligent anti-collision system (minimum detection distance 0.5m)