Bridge crane equipment, as an important part of the pipeline operation of iron and steel enterprises, belongs to special equipment, which is related to whether the production can be carried out in a normal and orderly manner. Bridge cranes are all working at high altitudes, and some metallurgical bridge cranes are dangerous to lift liquid metal during the working process. The state has clear requirements for the production, inspection, and scrapping of such equipment. For the replacement of some main parts of the crane, the basis for judgment is mainly based on the scrap standard. Therefore, in order to better maintain and use these equipment and avoid equipment accidents and safety problems, the following bridge crane scrap standards are specifically cited. I hope bridge crane maintenance personnel can strictly follow these standards to perform daily maintenance inspections.
The crane has been overhauled many times, and the main girder is severely depressed or cracked after being repaired twice, which marks the end of the safe service life. After being appraised by the competent authority and the safety technology department, you can apply for scrapping and updating the entire vehicle.
Deflection and cracks in the main girder of a well-designed and manufactured bridge crane are fatigue damage, which is a linear cumulative damage that is gradually formed by the partial cyclic slip and yield of the material structure under the action of alternating stress. Therefore, repeated severe deflection or multiple cracks mark the end of the safe service life of the main beam.
In general, the safe service life of the heaviest clamp cranes, grab cranes , cần cẩu điện từ, etc. is about 20 years; loading cranes, rake cranes, etc. are about 25 years; forging cranes and casting cranes are more than 30 years, universal Bridge cranes are 40-50 years old. The actual service life depends on the specific operating conditions, and may be longer or shorter.
1. When the gear wear on the first shaft of the hoisting mechanism reducer reaches 10% of the original thickness, when the gears on the remaining shafts reach 20% of the original tooth thickness
1) The wear of the gear on the first axis of the reducer of the large vehicle (trolley) operating mechanism exceeds 15% of the original gear thickness, and the wear of the gears on the remaining shafts exceeds 25% of the original gear thickness;
2) The wear of the initial gear is greater than 30% of the original tooth thickness;
3) The gears on cranes for lifting red hot or molten metals, acid solutions, explosives, flammable and toxic materials, etc. shall be reduced by half according to the above standards.
2. The working surface area of the gear damaged due to pitting corrosion on the tooth surface is greater than 30% and the depth exceeds 10% of the tooth thickness.
3. There is one or several fatigue cracks or broken teeth on the tooth root. ～40%; (3) The pitting area of the tooth surface should not exceed 60% of the tooth height and width.
The wheel should be scrapped when one of the following conditions occurs:
(1) There are cracks.
(2) The thickness of the wheel flange wears up to 50% of the original thickness.
(3) The tread thickness wears up to 15% of the original thickness.
(4) When the running speed is lower than 50m/min, the line profile can reach 1mm; or when the running speed is higher than 50m/min, the line profile can reach 0.5mm.
(5) There are pitting on the tread. When the wheel diameter is less than 500mm, the pitting diameter is greater than 1mm; or the wheel diameter is greater than 500mm, the pitting diameter is greater than 1.5mm, and the depth is greater than 3mm, and the number is more than 5.
When the hook has the following defects, it should be scrapped and replaced:
(1) Those with cracks, cracks or cracks on the surface shall be scrapped;
(2) The wear of the dangerous section exceeds 10% of the original size and should be scrapped;
(3) The dangerous section and the neck of the hook have plastic deformation and should be scrapped;
(4) The opening degree is increased by 15% compared to the original size and should be scrapped;
(5) The torsional deformation of the tip of the hook exceeds 10. The above should be scrapped;
The scrap standards for forged hooks are:
(1) There are cracks and ruptures on the hook surface. If cracks and ruptures are found, they should be replaced immediately. Repair welding is not allowed.
(2) When the height wear of the working section of the hook (at the lanyard) reaches 10% of the original height, it should be scrapped.
(3) When the hook mouth, hook neck and dangerous section of the hook are permanently deformed, they shall be scrapped; the hook mouth shall be scrapped if the opening degree exceeds 15% of the original size.
(4) The hook tail and thread transition section should be scrapped when there are knife marks or cracks.
1) The wall thickness of the pulley rope groove wears up to 20% of the original thickness;
2) The radial wear at the bottom of the pulley rope groove exceeds 50% of the wire rope diameter or the uneven wear exceeds 3mm;
3) Serious cracks were found in cast iron pulleys;
4) The rim of the pulley is seriously damaged.
The reel is used to wind the wire rope, transmit power, and convert the rotary motion into linear motion. The reel is usually cylindrical, and there are two types of single-layer winding and multi-layer winding. Gray cast iron is generally used, and large reels can be welded by steel plates. When the reel
1. Cracks or broken edges. One small horizontal crack is allowed, and two small vertical cracks are allowed (small holes should be drilled at both ends of the crack, and spot welding should be used to repair it). If it exceeds this limit, it should be scrapped;
2. The wall wear of the reel reaches 20% of the original wall thickness and should be scrapped.
3. The diameter of blisters and stomata should be no more than 8 mm, the depth should not exceed 25% of the wall thickness, and no more than 1 point per 100 mm. The blisters and stomata should be welded and polished.
(1) When there are defects or cracks on the working surface of the brake wheel, it should be scrapped and replaced;
(2) The unevenness of the wheel surface reaches 1mm or the depth of wheel friction damage reaches 2mm;
(3) The brake wheel flange of the hoisting mechanism wears up to 40% of the original thickness;
(4) The brake wheel of the operating mechanism wears up to 50% of the original thickness.
1. The number of broken wires in a hoisting machinery wire rope within a lay pitch reaches 10% of the total wire rope. For example, the rope 6×19=114 wire should be scrapped and updated when the number of broken wires reaches 12 wires. For example, the rope 6×37=222 wire should be scrapped and updated when the number of broken wires reaches 22 wires. For steel wire ropes composed of thick and thin wires, the number of broken wires is calculated as one thin wire and 1.7 thick wires.
2. If the radial wear or corrosion of the steel wire exceeds 40% of the original diameter, it should be scrapped. When it is less than 40%, the number of broken wires can be scrapped as required.
3. The number of scrapped wires of steel wire ropes used by hoisting machinery for lifting hot metal or dangerous goods shall be half of the scrap standard of steel wire ropes for general cranes.
4. For structural steel wire ropes that meet the requirements of the ISO2408 (General Purpose Wire Rope Characteristics" standard, the number of broken wires scrapped should be in accordance with the number specified in GB5972-86.
5. The whole strand should be scrapped if it breaks.
6. When the diameter of the wire rope is reduced by 7% or more relative to the nominal diameter, the wire rope should be scrapped even if no broken wires are found.
7. The exposed hemp core should be scrapped.
8. The steel wire rope has obvious corrosion and should be scrapped.
9. The elongation of the local outer steel wire in a cage-like state should be scrapped
10. Compare with the typical examples of steel wire ropes in GB5972-86, the ones with the same damage as in the picture should be scrapped.
For bridge cranes, which carry heavy objects, repetitive motion will naturally cause a lot of damage to its parts. Therefore, we need to understand the scrap standards of various parts in detail and replace parts in time to make the crane more Work safely and efficiently.
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