Factors such as lease price may also be comprehensively considered during specific implementation.
Requirements for tower crane structural parts: the tower crane structural parts shall be free from cracking, welding and serious deformation.
on October 31, a tower crane toppled at the construction site of a project under construction at Linqing intersection of Pingliang Road.
The design of torque limiter has defects and poor sensitivity; Unreasonable stress of steel structure design, design defects of hydraulic system and so on.
Quality problem of moment limiter element and material problem of steel used for steel structure; Quality problems of hydraulic system components, etc.
If the performance of the tower crane moment limiter is not understood enough, and it is not clear whether it really works, the accident will be caused by mistaking it for normal operation in the case of its failure.
Manufacturing problem 3.1 steel structure welding fails to meet the requirements.
If the main components and parts of the equipment have no production signs or paint the signs without authorization, they will be regarded as unqualified equipment and directly returned.
The inspection of the general contractor’s machinery management personnel is to recheck and supervise the inspection of the leasing unit.
It is required to check and maintain once a month (the contract will stipulate that there will be corresponding punishment measures for lack of).
Tower crane collapse accidents occur frequently.
The steel wire rope shall be free of broken wire, strand, burr, etc.
After entering the site, it shall be accepted and confirmed again.
The monthly inspection of many projects is to fill in materials and go through the motions, which is seriously irresponsible! During the monthly inspection, the special inspection of the leasing unit shall be carried out separately from the monthly inspection of the general contractor.
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2、 Causes of accidents caused by problems in use 1.
Picture Xinmin Evening News summarizes the causes of tower crane collapse accidents all over the country all year round.
Installation can be carried out only after it is qualified, and installation acceptance shall be carried out after installation.
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It is strictly prohibited to temporarily assemble installation and disassembly personnel.
Subcontracting selection and equipment control 1) large scale units shall formulate the company’s excellent leasing subcontractor selection method and assessment system, and determine the excellent subcontractor team of the unit through comprehensive assessment from the perspectives of enterprise scale, equipment quantity, registered capital and maintenance team personnel construction.
The operator’s daily inspection and maintenance of the equipment are not enough, resulting in potential mechanical safety hazards of the tower crane.
3.2 the geometric dimension of steel structure is inconsistent with the requirements.
Many units have only achieved pre job training, ignoring the continuous training and improvement of operators in operation skills and safety awareness, and ignoring the continuous training of commanders.
In this way, the mobilization and demobilization of defective equipment are easy to avoid.
Construction media ID: jianzhong001 Shanghai Yangpu District Government informed that at 7:22 a.m.
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The problem of factory certificate and operation manual, without factory certificate, is a fake and shoddy product.
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The process management equipment will not have major problems after careful pre mobilization acceptance and installation acceptance.
The blanking is not in accordance with the requirements, and the steel section size cannot meet the provisions of the national standard.
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However, in the process of use, new hidden dangers will be generated due to environmental changes.
Operators and commanders operate and command against rules.
Maintenance capacity: the general fault of tower crane shall be solved within 4 hours and the major fault shall be solved within 2 days.
It is easy to figure and imagination.
Violation of disassembly and assembly procedures during installation and disassembly.
The standard section of tower crane shall not be mixed.
III.
There is no scheme for installation and disassembly and no safety technical disclosure, based on experience.
Design problems.
Electrical limit requirements of tower crane: the electrical circuit of tower crane shall be free of aging and cracking, the PE line shall be connected, and the limit cover shall be complete, sensitive and effective (especially the rope breaking protection device shall not be deformed).
At present, one tower crane driver was killed and two passers-by were slightly injured.
Tower crane structural parts shall not be welded or altered without permission.
Operators and commanders work without certificates.
All bolts used on site shall be free of serious corrosion, deformation, shrinkage and wear.
3.
The use unit and disassembly unit of the tower crane did not handle the disassembly application and acceptance procedures according to the regulations, and lost the opportunity to be checked by the competent government department.
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How to prevent them in 2021? Please refer to these three aspects.
First, adhere to the management of equipment service life, select famous brand products, and focus on avoiding the safety risks caused by the use of old equipment.
All standard section bolts shall be opened (including in the frame), and the rust shall be cut off.
At this time, monthly maintenance and inspection are particularly important.
The installation and disassembly team is unqualified and undertakes disassembly and assembly tasks without certificates.
2.
Ignoring human factors, such as what range and how much can be suspended, and having no bottom or unclear in mind.
If there is any infringement, please contact to delete!) long press the QR code to follow us ▶▶▶。.
Once mobilized and installed, it is difficult to rectify.
The height of the weld is not enough, and there are defects such as pores, slag inclusion and even false welding.
For the equipment that has been used in the unit and the maintenance ability of the leasing unit is strong, the service life can be appropriately relaxed.
Do not handle the disassembly application and acceptance procedures.
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After mobilization, the installation can be started only after it is accepted again.
Spare parts.
3) Contents of inspection and acceptance before equipment mobilization: 1.
All pin shaft cotter pins are complete, three wires of bolts and nuts are exposed, and bolts, gaskets, spring washers, nuts or gaskets and double nuts.
The leasing unit is required to have a permanent workplace (to be inspected), and all leased tower cranes have their own property rights without attachment.
(source: integrated on the Internet, the picture and copyright belong to the original author.
The scene of the accident is being cleaned up, and the specific cause is still under investigation.
2) Before the equipment enters the site, the machine manager or machinery management personnel shall conduct on-site inspection, select qualified equipment and take photos for filing before entering the site.
3、 Causes of accidents caused by quality problems of tower crane products 1.
All parts of a single brand tower crane shall be consistent and purchased from the original factory.
Self management status: Leasing unit with manufacturer background is preferred.
Old equipment shall be maintained before entering the construction site.
Note: the above three articles are drawn up from the perspective of the user, which may infringe on the interests of the leasing unit.
There are no more than three aspects: first, the installation and disassembly of tower crane, second, the use of tower crane, and third, the quality of tower crane itself.
The unit has perfect management system and technical support capacity (tower crane foundation construction, wall attached position embedding and other nodes).
1) The leased tower crane shall use the equipment within 5 years as much as possible, and the leased construction elevator, material elevator and electric hanging basket shall use the equipment within 3 years as much as possible.
There is no batch description, and the changes to the original design are not indicated.
In particular, there are welding quality problems at important connecting parts on tower cap, boom, balance arm and other components.
Many hidden dangers actually occur before mobilization.
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2) QTZ40 and below tower cranes are not used.
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Tower crane collapse II.
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The disassembly and assembly unit did not prepare the disassembly and assembly plan, did not carry out safety technical disclosure, and acted recklessly in violation of rules and regulations based on experience, which was the direct cause of the accident.
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Requirements for installation and disassembly capacity: it is preferred to have a fixed and own installation and disassembly personnel team, and the enterprise also has installation and disassembly qualification.
In the process of disassembly and assembly, the disassembly and assembly unit does not carry out disassembly and assembly according to the sequence of disassembly and assembly in the tower crane operation manual, and does not operate according to the disassembly and assembly scheme and the requirements of safety technical disclosure.
However, the ultimate goal is to prevent some hidden dangers that cannot be rectified on site from entering the site with diseases by selecting famous brands and equipment with short service life.
Insufficient education and training for operators and commanders.
The personnel, equipment and technology of the installation and disassembly unit do not meet the requirements, which is an important cause of the accident.
The tower crane driver and commander did not receive professional training and obtain qualification certificate as required, and did not have corresponding professional skills and knowledge.
1、 Reasons for accidents caused by problems in installation and disassembly 1.
For example, overload hoisting, inclined hoisting, hanging the concrete pump delivery pipe with a tower crane at the construction site, beating concrete and rotating at will, etc.
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