1. The application scope of the new standard is clearer.
The new standard mainly stipulates the safety technical requirements that should be observed in the design, manufacture, installation, use, maintenance and inspection of tower cranes. It is suitable for building tower cranes and can also be used as a reference for other tower cranes. This standard does not apply to mobile cranes.
2. The abbreviation of tower crane is more accurate.
The new standard calls tower crane: tower crane. In the old standard, tower crane was called crane for short. According to the Regulation on Supervision and Inspection of Hoisting Machinery (No.296 [2002] of China Quality Inspection Pot), the general scope of cranes includes: bridge cranes, portal cranes, tower cranes and mobile cranes. Obviously, the abbreviation of the old standard is very vague, and the new standard corrects the dislocation relationship between broad concept and narrow concept, which is more accurate.
3. The new standard emphasizes the integration with international standards.
In order to enhance the ability of our country's tower crane products to participate in the international market competition, the new standard emphasizes international integration and adopts the relevant contents of ISO international standard. On the basis of referring to American ASME standard, British BS standard, German DIN standard and Japanese JIS standard, the new standard directly adopts ISO 7752-3: 1993, ISO1660-1:1999 and ISO16599. For example, in Articles 4.3 and 4.4 of (1), the strength and height of platforms, ladders and treadboards are selected from ISO11660-1:1999. (2) ISO11660-3:1999 is selected for the content and schematic diagram in Article 4.4. (3) In the seventh operating system, the contents of ISO 7752-3: 1993, the layout of the control system and the recommended operating force are selected. This move provides technical support for the export of tower crane products in China.
4. There is a difference between mandatory standards and recommended standards.
The new standard supplements and adjusts the contents of the old standard in many places, and the standard clauses are distinguished strictly according to mandatory standards and recommended standards. According to the "Several Provisions on Implementing Compulsory Standards" issued by the State Bureau of Quality and Technical Supervision, the new standard lists the clause 1 13 for protecting personal health and property safety as a mandatory clause, and adds and adjusts the clause 3 1 as a recommended clause. There are 144 items in the new standard, which is 15 items more than the old standard.
5. New regulations have been made for the random technical documents of manufacturers' products.
In view of the non-uniform and non-standard technical documents of manufacturers, users lack basis in tower crane management and operation. In the new standard, the requirements for operating instructions are added in Article 3.6, which stipulates that "the operating instructions for tower cranes shall not only comply with the provisions of 7.2.6 in Technical Conditions for Tower Cranes GB/T9462- 1999, but also include the following eight contents: (1) The tower crane shall be based on the low-temperature mechanical properties and the mechanical properties of the materials used for the main load-bearing structural parts of the tower crane. (3) The tower crane with counterweight installed before installing the boom shall be marked with the quantity, specification and position of counterweight; (4) After the boom is assembled, the inspection items and inspection methods of pin shaft, installation positioning plate and other connectors; (5) Safety operation steps, balance measures, inspection parts and inspection items in the process of adding and descending tower sections; (6) Type, specification and length of wire rope used; (7) Pre-tightening force or torque required for high-strength bolts and inspection points; (8) The center of gravity of each combination length of the boom and the balance arm and the position of the lifting point for disassembly and assembly.
6. Increase the safety reserve conditions from the aspects of design and manufacture.
In order to improve the safety of installation and disassembly of key parts of tower crane, and prevent the tower collapse caused by the falling of boom, the standard increases the reserve requirements for design and manufacture to improve safety, such as Article 6. 1 1: "Jack-up tower crane should have the function of preventing the boom from falling off the tower support during normal insertion and descent operations." Article 3.3 stipulates: "When the jack-up tower crane is engaged in the joint-adding operation, even if the piston rod of the jack-up cylinder extends all the time in any jack-up cycle, the upper end face of the tower body should be at least 60mm higher than the center line of the guide wheel (or sliding sleeve) on the jack-up jacket."
7. Improve the man-machine working environment from the perspective of humanization.
In order to improve the safety and applicability of drivers, the new standard has been revised and supplemented a lot, which has improved the man-machine working environment and increased environmental conditions. Among them, six new requirements have been added to the design and manufacture of cab. According to Article 6 of 4.6.2-4.6.7; Tempered glass or laminated glass shall be used for cab door and window glass. The front glass of the cab shall be equipped with wipers. The mobile cab shall be equipped with locking device. The driver's cab should be equipped with fire extinguishers that meet the fire protection requirements. For the console placed at the lower part of the tower crane, there should be a ceiling above it, and the ceiling pressure test should comply with the provisions of 4.2 in JG/T54- 1999. Cab should be ventilated, warm and rainproof; The inner wall shall be made of fireproof materials; The floor should be insulated. When the indoor temperature of the cab is lower than 5℃, a non-naked heating device should be installed; When the indoor temperature of the driver is higher than 35℃, a heatstroke prevention ventilation device should be installed. The floor-to-ceiling windows of the cab shall be equipped with protective railings.
8. Completely solve the driver's right to know about safe operation.
Due to the high mobility of drivers of tower crane users, some drivers have accidents due to improper distribution of instructions without knowing the lifting performance and main parameters of tower crane. In order to avoid this situation, Article 3.5 is added to the new standard, "Signs or display screens of common operation data should be installed in the cab of tower crane where it is easy to observe. The contents of the signboard or display screen shall include amplitude load table, main performance parameters, lifting weight of each lifting speed gear, etc. Signs or display screens should be firm, reliable, clear and eye-catching. At the same time, in article 1 1.2, it is required that a complete operation and maintenance manual must be kept in the cab of the tower crane driver.
9. Increase the requirement that subsequent supplementary load-bearing structural members must be consistent.
In order to prevent the main load-bearing structural parts of tower crane from failing to meet the performance requirements of the original tower crane, the new standard stipulates that the performance must be consistent before and after. In Articles 4.8, 4.9. 1, 4.9.2 and 4.9.3, it is required that the structural components of tower cranes, such as standard joints, boom joints, tie rods and tower caps, should have permanent marks that can trace the factory date. The standard sections of different specifications of the same tower crane should have permanent distinguishing marks. After the jack-up tower crane leaves the factory, the subsequent structural parts (standard section of tower body, embedded section, foundation connector, etc.). ) should not reduce the bearing capacity of the original tower crane, can't increase the structural deformation of tower crane. During jack-up operation, the accuracy of clearance between rollers (slideways), contact coincidence of rollers (slideways) and the accuracy of step position of the original tower crane shall not be reduced. For installation and disassembly, the installation accuracy of the original tower crane connecting pin hole and connecting bolt hole shall not be reduced.
10. Added the key points to avoid safety risks in tower crane installation.
In order to prevent serious accidents caused by falling off the connecting pin of the boom and welding the baffle at the pin end, the new standard puts forward four requirements that must be avoided in view of various safety risks existing in the installation process of tower crane. (1) Clause 4.2.2 stipulates that "the positioning structure of the connecting pin of the crane boom shall meet the safety and reliability requirements under the condition of frequent disassembly". (2) Article 10. 1.2 stipulates that "before installing or adding the standard section of the tower body, the tower crane shall inspect the structural members and high-strength bolts. If the following problems are found, they should be repaired or replaced before installation: 1) visible structural cracks and welding cracks; 2) The shaft and hole of the connector are seriously worn; 3) The parent metal of structural parts is seriously corroded; 4) Plastic deformation of the whole or part of the structural member and plastic deformation of the pin hole. (3) Article 10. 1.3 stipulates that "before the jib is assembled and ready for hoisting, check whether the connecting pin shaft of the jib is firmly and reliably connected with the installation positioning plate. When the shaft end of the boom connecting pin shaft adopts welded baffle, after hammering the pin shaft, check whether the weld of the shaft end baffle is normal. (4) Article 10.2 stipulates that "when installing, disassembling, adding nodes or reducing nodes, the wind speed at the maximum installation height of tower crane shall not be greater than 13m/s (equivalent to level 4 wind). When there are special requirements, it should be implemented according to the agreement between the user and the manufacturer. " Compared with the original standard (equivalent to 6 winds), the safety requirements are improved.
1 1. improves the requirements for the reliability of parts.
In order to improve the reliability of the connection of parts of tower crane, the new standard requires that the design and manufacture should not only consider the structural stress, but also fully consider the unfavorable factors of frequent installation and disassembly of tower crane on the connection of parts, and add the 4.2.2.3 clause "The connecting pin of the lower chord of the trolley horn of jack-up tower crane should not be in the form of bolted shaft end baffle." When the shaft end of the connecting pin shaft is welded with a baffle, the thickness of the baffle and the welding seam should have sufficient strength, and the baffle and the pin shaft should have sufficient overlapping area to prevent the pin shaft from being adversely affected by hammering force and rotation during installation and work. "
12. The conditions for safe use of wire ropes are more stringent.
The new standard clearly stipulates the safe use conditions of wire rope from three aspects. First, in order to prevent the high-altitude pulley wire rope from breaking due to the excessive gap between the ropes and damaging the wire rope system, it is required that the hoisting wire rope and the hook should be equipped with anti-falling devices. It is stipulated in Article 6.6 that "the pulley, hoisting drum and luffing drum of the boom shall be equipped with a wire rope anti-falling device, and the clearance between the device and the outermost edge of the pulley or drum side plate shall not exceed 20% of the diameter of the wire rope. The hook shall be equipped with a wire rope anti-dropping device ". Second, the car is required to be equipped with a broken rope protection device to increase the emergency defense capability. In Article 6.5, it is stipulated that "the tower crane with variable amplitude trolley shall be equipped with a broken shaft protection device for variable amplitude trolley, so that the trolley will not fall even if its shaft is broken". Three, lifting wire rope should use non-rotating wire rope or anti-torsion device. In order to prevent the wire rope from rotating in the air, it will cause unnecessary trouble in the lifting process. In article 5.2.4, it is stipulated that "the hoisting wire rope of tower crane should use non-rotating wire rope. When the non-rotating wire rope is not used, the rope end should be provided with an anti-torsion device. "
13. The safety tips for the height of rail top of tower crane are given.
In order to prevent the tower crane on gravel foundation from being pushed out of the track because the height of the rail top in the middle of the track is higher than that at both ends, and the tower crane may be pushed out of the track in case of a strong typhoon, or the tower crane landslide derailment accident may be accidentally caused, a recommendation clause has been added in the new standard, that is, the article 10.8e "The height of the rail top at both ends of the track stroke should not be lower than the height of the highest point in other parts".
14. The electrical system of tower crane was supplemented and adjusted.
The new standard adopts TN-S neutral protection system specified in Technical Specification for Temporary Electricity Safety in Construction Site (JGJ46-2005), and adds 8. 1.7 and 8. 1.8 "The insulation resistance of main circuit and control circuit to ground should not be less than 0.5MΩ". The neutral wire and the grounding wire must be separated, and it is forbidden to use the grounding wire as a current-carrying circuit.
15. Improve the requirements for tower crane maintenance conditions.
In order to improve the working conditions of maintenance workers and ensure the safety of operation, the new standard is more thoughtful and specific than the old standard. Ladders, handrails, guardrails and boom walkways are supplemented and modified from seven aspects, and the safety guarantee coefficient is increased.
16. Obviously, the safety braking device should not be replaced by other devices.
In view of the customary understanding and practice that some designers and manufacturers regard the worm gear reducer as "a device with the same braking function", it is clearly stipulated that the self-locking device of the worm gear reducer cannot replace the brake. Clause 5.5. 1 of the new standard retains the first half sentence of the original clause "the hoisting, slewing, luffing and traveling mechanism of tower crane should be equipped with brakes", and deletes the provision of "or devices with equivalent functions" in the original clause. It has solved the important problems of different concepts and different equipment safety performance for a long time. Avoid safety accidents caused by defects in safety devices.
In a word, compared with the old standard, the new standard has higher safety and quality reliability, wider coverage and better operability, which plays an important technical guidance and constraint role in improving the safety and quality of tower crane design, manufacture, installation, use, maintenance and inspection.
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