National Standards For Metallurgical Bridge Cranes

National Standards for Metallurgical Bridge Cranes
 

1.  For the use of general-purpose bridge cranes to lift molten metal, casting cranes that meet the requirements of JB/T7688.15-1999 "Technical Conditions of Metallurgical Cranes for Foundry Cranes" shall be used. In addition to meeting the regulations and standards of general bridge cranes, the following basic technical requirements must be met:
 

(1) Use a special motor for metallurgical lifting. When the ambient temperature exceeds 40 ° C, a motor with H-class insulation should be selected;
 

(2) Equipped with two sets of independently acting brakes (double brakes);
 

(3) Lifting capacity limiter must be installed;
 

(4) Equipped with double limiters (double limiters) of different forms (generally hammer type and rotary type combined), and should control different circuit breakers. For cranes with a lifting height greater than 20m, also The lower limit position limiter should be installed according to the need;
 

(5) Use thyristor stator voltage regulation, eddy current brake, energy consumption brake, thyristor power supply, DC unit power supply speed regulation and other hoisting mechanisms that may cause overspeed due to speed regulation and general-purpose equipment for lifting molten metal above 20t Overhead cranes must have overspeed protection;
 

(6) The hoisting mechanism should have a forward and reverse contactor fault protection function to prevent the motor from being de-energized while the brake is still energized, resulting in a stall;
 

(7) The protection level of all electrical equipment should meet the requirements of relevant standards;
 

(8) Hoisting machinery that has been working in a high temperature environment for a long time needs to take protective measures for its electronic control equipment;
 

(9) Choose a wire rope that is suitable for high temperature occasions and has a sufficient safety factor;
 

(10) Do not use cast iron pulleys;
 

(11) Cranes whose working level is lower than A6 (excluding A6) should be used with a reduced load, and the reduction should be determined according to the actual working conditions, but the specified lifting capacity after the load reduction shall not exceed 80% of the original rated lifting capacity.
 

2. For all kinds of hoisting machinery with a rated lifting capacity greater than 10t and using an electric hoist as a hoisting mechanism, it is not allowed to lift molten metal.

3. For all types of hoisting machinery with a rated lifting capacity less than or equal to 10t and using metallurgical electric hoists as the hoisting mechanism to lift molten metal, the original crane must be replaced or modified to meet the following basic technical requirements:

(1) Do not use ordinary electric hoist as lifting mechanism;
 

(2) With support brake and safety brake;
 

(3) There are different types of rising double stoppers (cranes with a lifting height greater than 20m should also be equipped with a lowering limit position stopper);
 

(4) With weight limiter;
 

(5) Electric hoist with high temperature and heat insulation protection function;
 

(6) It has a sufficient safety factor for the working condition of lifting molten metal, and the working level must reach M5 level (including M5 level);
 

(7) Choose a wire rope that is suitable for high temperature occasions and has a sufficient safety factor;
 

(8) Use remote control and other manipulation methods far away from heat sources as far as possible, otherwise a safe passage for operators must be provided.
 

4. The regular inspection cycle of cranes for lifting molten metal is shortened from 2 years to 1 year.