What are the differences between metallurgical cranes and ordinary cranes

Metallurgical cranes refer to bridge cranes used in metallurgy, casting and other places where molten metal is lifted. It can be divided into metallurgical single-beam cranes and metallurgical double-beam cranes. Part 5 of the Safety Regulations for Lifting Machinery (Bridge and Gantry Cranes) specifies the safety rules for bridge cranes. In addition to meeting the various requirements of ordinary cranes, metallurgical cranes should also meet the following requirements:

1. Anti-radiation heat device and fireproof board

• 1.1. The bottom of the driver's cab directly exposed to heat radiation of the crane that lifts molten metal or hot objects should be equipped with a heat radiation protection plate.
• 1.2. Cranes for lifting molten metals or hot objects (except cranes with the following flanges as running rails) directly exposed to radiant heat should be installed at the bottom of the main beams and lifting beams to prevent radiant heat.
• 1.3. For cranes that use the following flange as the running track and lift molten metal or hot objects, a heat-radiating device should be provided at the bottom of the drafting trolley.
• 1.4. The anti-heat radiation board should be equipped with reliable anti-falling measures.
• 1.5. For cranes directly affected by flames (such as steel mill feeding span casting cranes), it is advisable to install fire-proof panels on the main structure where the flames directly burn.
• 1.6. Insulation layer should be provided at the wiring part of the channel and platform where the crane lifting molten metal or hot objects is directly exposed to radiant heat.
• 1.7. For cranes that lift molten metal or hot objects, protective measures should be taken for electrical equipment directly exposed to radiant heat.

2. Cranes that lift molten metals or hot objects should use a closed driver's cab. An effective thermal insulation layer shall be provided, and the thermal insulation layer shall be made of flame-retardant material.

3. Requirements for metallurgical crane mechanism:

• 3.1. The main hoisting mechanism of the crane for lifting molten metal (except electric hoist} The drive chain should meet the following conditions~,
  • a) The main hoisting mechanism is equipped with two sets of driving devices, which are rigidly connected to the output shaft;
  • b) The main hoisting mechanism is equipped with two sets of driving devices. When there is no rigidity continuous on the output shaft or when the main hoisting mechanism is equipped with a set of driving devices, a safety brake shall be set on the wire rope coil;
  • Note: Two sets of driving devices refer to two motors, two sets of deceleration systems, one or more sets of winding devices and four sets of brakes.
  • c) For cranes with a rated lifting capacity not greater than 16t, the working level of the hoisting mechanism should be at least 2 levels higher than that required by the actual operating conditions, and the minimum working level should not be lower than M5.
• 3.2. For cranes for lifting molten metal, the steel wire of the main hoisting mechanism shall meet the following regulations:
  • a) A four-wire rope winding system shall be adopted for double lifting points;
  • b) At least two steel wire rope winding systems shall be used for single lifting point;
  • c) The safety factor should comply with the relevant regulations in GB/T 3811, for cranes with a rated lifting capacity of not more than 16t. Its safety factor should not be less than 5.6.
• 3.3. For cranes that lift molten metal, the steel wire rope winding system of the main hoisting mechanism should not use balance pulleys.
• 3.4. For cranes for lifting molten metal, when the rated lifting capacity is not more than 16t, electric hoist can be used as the lifting mechanism. In addition to the requirements of JB/T 9008 (all parts), the electric hoist should also meet the following requirements:
  • a) When the rated lifting capacity is greater than 5t, the electric hoist should be equipped with a safety brake in addition to a working brake. The safety brake is set on the low-speed level of the electric hoist. When the working brake fails or the transmission component is broken, it can reliably support the rated load.
  • b) When the rated lifting capacity is less than or equal to 5t, in addition to a working brake, the electric hoist should also be equipped with a safety brake at the low speed level, otherwise the electric hoist should be designed at 1.5 times the rated lifting capacity.
  • c) Use electric hoist with high temperature insulation function.
  • d) The working level of the electric hoist should not be lower than M6.
• 3.5 Crane for lifting vertical and throwing heat treatment process workpieces. The brake of the hoisting mechanism shall be equipped with an emergency release device.
• 3.6 The objects lifted by the forging crane are placed on the supporting surface. Withstand regular impact loads and produce vertical displacement. The corresponding lifting mechanism should be equipped with a buffer device and a brake release mechanism.

4. Parts requirements:

4.1, wire rope

• 4.1.1. The crane for lifting molten metal or hot objects should use high temperature resistant steel wire rope with a performance not lower than the metal rope core or metal strand core specified in GB 8918.
• 4.1.2. Crane for lifting molten metal. The safety factor should comply with the relevant regulations in Table 44 in GB/T 3811-2008. For cranes with a rated lifting capacity not greater than 16t, the safety factor should not be less than 5.6.

4.2 Pulley

• 4.2.1. Gray cast iron pulleys should not be used for lifting and transporting molten metal.
• 4.2.2. Rolling pulleys are recommended for metallurgical cranes. When using cast wheel, it should meet the requirements of GB/T 27546.

4.3 Spreader

• 4.3.1. For the welding fork of a crane for lifting molten metal, its force direction should be consistent with the direction of the fiber extension of the steel plate, and the mechanical properties of the steel plate should not be lower than the Q345B steel plate in Table 1 of GB/T 1591-2008 .
• 4.3.2. There should be no butt weld on the lower flange plate of the lifting beam of the crane for lifting molten metal.
• 4.3.3. The main load-bearing parts of the lifting beam towel of the crane for lifting and transporting molten metal, such as the side plate of the pulley block, the lug plate, etc., when the plate thickness exceeds 0.04m. Ultrasonic testing should be carried out before blanking, and it should reach the level I quality specified in Table 4 of GB/T 2970-2004.
• 4.3.4. For cranes that lift molten metal, measures should be taken to protect the wire ropes from the direct influence of radiant heat at the hook group and lifting beams, and to prevent molten metal from splashing onto the wire ropes.
• 4.3.5. When the hot objects and workpieces lifted by the crane need to enter the liquid medium, measures should be taken to prevent liquid splashing at the moving pulley block of the hook.
• 4.3.6. A rough material crane used for handling and stacking rod-shaped billets during continuous casting and rolling in steel mills. The coarse teeth of the material target should be made of Q345 steel whose material properties are not lower than those in GB/T 1591-2008 Table 1, and the butt joint of the rake teeth; that is, the seam should be well known, and the post-weld annealing treatment should reach GB/T 3323 by radiographic inspection. The quality requirements for welded joints of Grade BII in the standard; ultrasonic testing should meet the quality requirements of Grade 1 in JB/T 10559.

5. Lifting mechanism for lifting molten metal and other dangerous goods. The brake control should take measures to prevent control failure due to damage or adhesion of a contactor.

6. The cables directly exposed to heat radiation on cranes that lift molten metals and hot objects should use flame-retardant and high-temperature resistant cables or take thermal insulation measures for the cables.

7. The crane for lifting molten basic metal or hot objects should adopt the operation method far away from the heat source such as the driver's cab, remote control or non-following type, and ensure the operating vision of the operator. The crane adopting remote control or non-following operation mode should be provided with safe passage for operators.

8. For cranes that lift molten metals and other dangerous goods, the lifting mechanism should be equipped with overspeed protection, except for electric hoists with a rated lifting capacity of not more than 5t.

9. For cranes that lift molten metal, the main lifting mechanism should be equipped with different forms of dual secondary protection devices at the rising limit position, and can control different circuit breakers. When the lifting height is not greater than 20 m, the falling limit should also be set Position limiter.

10. For cranes for lifting molten metal, when the main hoisting mechanism (except electric hoist) is equipped with two sets of driving mechanisms and the output shaft is not rigidly connected or when a set of driving mechanism is set, safety brakes should be set on the steel wire rope drum. For cranes that lift molten metal with a rated lifting capacity of not more than 16t and greater than 5t, in addition to a working brake, the electric hoist should also be equipped with a safety brake on the low-speed level of the electric hoist. If the rated lifting capacity is not more than 5t, the electric hoist shall not In addition to setting a working brake, a safety brake should also be set on the low-speed level of the electric hoist, otherwise the electric hoist should be designed at 1.5 times the rated lifting capacity.

The use of metallurgical cranes is a kind of equipment that is more dangerous than ordinary cranes. The relevant units should purchase products through manufacturers with production qualifications and accept inspections by special inspection departments.

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