Discussion on the safe use and management of mater

2022-08-26
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Discussion on the safe use and management of material hoists

material hoists are a common vertical transportation machinery on construction sites. Compared with tower crane and construction elevator, it has the advantages of simple structure and easy fabrication. With flexible installation and disassembly, convenient use and low price, it is a construction machine with less investment and significant benefits, which is widely used in building construction. Because of these characteristics of material elevator, it is easy to cause people's insufficient understanding and neglect of management. And cause mechanical equipment accidents such as overturning, basket falling from high altitude and top punching casualties. Material hoists account for a considerable proportion of equipment safety accidents. In order to ensure the safe use of material hoists, manufacturers, construction enterprises, equipment managers and safety managers must attach great importance to its safety management and include it in the management of lifting machinery. According to the characteristics and weaknesses of the material elevator, the inspection and acceptance shall be carried out one by one according to the standards before use

the material hoist is mainly composed of winch and frame. The winch can be purchased from the manufacturer as needed. Due to its simple structure and weak production link management, when (d1+ D2)> 13, the size deviation and appearance quality of the frame are unqualified non-standard products. Some manufacturers produce for small manufacturers, and some make for themselves. Due to the lack of basic production equipment and technical force, the process is backward, so the product quality and the quality of the frame cannot be guaranteed. The stability of the metal structure is poor, and the verticality after installation cannot reach the due standard. The rigidity and strength of the whole machine cannot meet the requirements of construction and production. Ordinary bolts are mostly used for the connection of rods, and the connecting plate of standard section is thin and has insufficient strength, so it cannot form a stable structure. In order to reduce costs, some construction units use scaffold steel pipes as the main limbs of standard sections, and even the main limbs and webs are still in use due to deformation, leaving various potential safety hazards

due to the simple structure of the material hoist, many construction units have insufficient understanding of the safety performance requirements of machines and tools, and Despise its installation and acceptance. Most of the installation personnel are non professionals, and the installation and disassembly personnel have not obtained the post safety qualification and take up their posts without certificates. In some construction units, the erection of the anti material hoist is regarded as the erection of scaffolding, which is installed and dismantled by scaffolders. No targeted safety technical disclosure was made in advance, and the operation plan was prepared according to the situation of the construction site. Moreover, there is no due technical supervisor to approve and examine the scheme, resulting in potential safety hazards in the installation of material hoists

the structure of the material elevator is simple, and the operation is completely controlled by human behavior. Therefore, it is necessary to install various protective devices to prevent misoperation and safety accidents. The safety devices of material hoists generally include safety stopping devices, rope breaking protection devices, upper and lower limit limiting devices, overload limiters, cage safety doors, buffers, safety protection doors at the inlet and outlet of materials, anti smashing protective sheds, anti falling safety stands and other safety facilities. Some of these safety devices and facilities are required by the hoist itself, and some are safety measures that must be taken for on-site use. The supplier and user of the machines and tools should cooperate with each other to meet the requirements of their safe use. However, at present, many material hoists have incomplete safety devices. The protective shed and safety door erected by the user unit do not meet the requirements. The manufacturer and user of the hoist argue about who should improve the safety protection facilities, which has become another prominent safety hazard in the construction and production of the hoist

the current specifications for material hoists include safety technical specifications for gantry and derrick material hoists and JGJ. The inspection standards are "building construction inspection standards" and "jgj59 selection interface, experimental parameter selection interface, experimental operation and result display interface and curve display interface-99". These two national industry standards put forward various mandatory regulations on the safe use requirements of material hoists, which must be implemented to the letter

first of all, the supervision of material hoists should be strengthened, and the supervision and management of production and manufacturing links should be strengthened. The products produced by the manufacturer must meet the requirements of the safety technical code for gantry and derrick material hoists, and can withstand the inspections in the checklist of material hoists (gantry and well frame) in the standard for inspection of building construction. The products of the manufacturer shall be subject to the expert safety technical review organized by the provincial competent department of construction industry, and shall be registered for the record. Merchants and manufacturers should not exaggerate the use performance of products at will, and use low frame hoists as overhead hoists. At the same time, the qualified products of the designated manufacturer shall be purchased, and the manufacturer shall issue the product certificate and the copy of the production license. The self-made material hoist shall not only comply with the safety technical specifications for gantry and derrick material hoists, but also comply with the current national safety regulations for cranes and other relevant standards, and put forward design schemes, drawings, calculations and quality assurance measures. Report to relevant superior departments and chief engineer for approval. The structural steel shall be used as the scaffold material, and the scaffold steel pipe shall not be prefabricated into standard parts or standard sections, which shall be assembled at the construction site according to the design drawings

the installation personnel of the hoist should have certain installation quality, understand the basic principles of machinery, installation and disassembly procedures, and obtain qualified safety qualification and work with certificates after receiving technical training of lifting machinery specifications and standards. The installation personnel must be fixed and specially assigned for installation and removal. According to the plan approved in advance, safety technical disclosure, divide the safety warning area for installation and demolition. If there is no professional personnel for installation and removal, the operators shall be installed and removed by special operators who have obtained the operation certificate for high place operation under the supervision of the safety officer under the technical guidance of professional technicians on the basis of the scheme disclosure

after the installation of the material elevator, it should be accepted before use. At this stage, most of the material hoists are still accepted by the construction unit internally or by the unit renting the equipment and the user. It has not been fully included in the acceptance scope of the testing institutions that have obtained the testing qualification of hoisting machinery in the society. However, no matter what form of acceptance, the contents and conclusions of the acceptance should be in the form of words. On the basis of fully meeting the specifications and standards, both parties should jointly sign, file and put on record. After the acceptance is qualified, it can be delivered for use. The acceptance content of the material elevator should include the following main aspects. Foundation, frame and safety device. Wind rope or wall attached pull rod, steel wire rope, floor unloading platform protection, hanging basket, mechanical transmission system, winch operation shed, electrical circuit, load test, acceptance conclusion and the signature of relevant acceptance personnel. The following aspects that are prone to problems are discussed:

the foundation of material elevator must be placed on the soil layer with a bearing capacity greater than 80kPa after compaction according to the specification requirements. The grade of foundation concrete is greater than C20, and the thickness is greater than 300mm. In order to ensure the verticality of the frame column, the foundation levelness is required to be super flat, and the deviation should be within 10mm

the frame body shall be free of horizontal distortion, and all members shall be free of bending and deformation. The outer side of the frame body shall be sealed along the full height with a special safety seal for the derrick

the superelevation limit device is sensitive and effective, and the distance from the ceiling beam is not less than 3m. The bumper of the floor parking device must be reliable and stereotyped. When the bumper is leveled on the basket, it must enter the measuring leg of Newtonian elongation fixed on the frame column. When personnel unload on the basket, all the weight on the basket is transferred to the frame column through the bumper. At this time, the hoist wire rope only plays a safety role. Because of this kind of operation of bumper, the setting of bracket must be accurate. The flat bumper of the basket must enter the bracket. Otherwise, the safety device is regarded as a virtual device

in addition to setting the wind rope according to the regulations, the ground anchor is also an important part. At the construction site, the ground anchors of the material hoist are mostly pile anchors, which are driven underground with scaffold steel pipes. According to the specification, there should be no less than two pile type ground anchors in one place, set side by side, with a spacing of no less than 0.5m, and a driving depth of no less than 1.7m. The top of the pile should be provided with cable wind rope anti-skid measures. However, a considerable number of wind cables are not set according to this setting

the material and method of connecting rod attached to the wall shall meet the specification requirements. In order to ensure the clarity of the force on the rod and not be disturbed by other external forces, it is required not to be connected with the scaffold, nor with the outer side of the frame along the full height protection fence. The members attached to the wall must be set independently and form their own system

the scaffold board of the floor unloading platform is set up tightly and firmly. Both sides of the unloading platform shall be equipped with protective railings and protected by dense mesh safety. The protective door of the platform is finalized, and the work is safe and reliable. Single door can be made into push-pull type. Double doors are open horizontally, but must be opened and closed towards the building on the floor. After the unloading personnel leave, it should be closed at any time. The protective shed at the ground feed inlet is mainly set up for the feeding personnel to avoid the impact of high-altitude objects, which should be effectively avoided according to the specifications. This requires the protective shed to have a considerable length, width and impact resistance

the basket should be equipped with safety doors, safety railings should be set on both sides of the basket and hung safely to prevent objects in the basket from falling higher. In order to ensure the firmness and reliability of the basket bottom plate, the load nuts, bearings and other positions should be regularly and smoothly paved with 5cm wooden boards

the steel wire rope of the winch drum should be wound neatly without random lines. The winch should be fixed with foundation bolts or ground anchors. Making ground anchors requires the winch chassis to be lifted in front and pulled back

in addition to rain proof and smash proof, the winch poplar shed should have a good view of the material hoist and should not be blocked by obstacles

the three-phase five wire system shall be adopted for the power line, the winch shall be connected to neutral for protection, and the electric box shall be equipped with leakage protector. The frame shall be equipped with lightning arrester, and the resistance value of the grounding body shall not be greater than 10 Ω

the material hoist should be hung with a safety operation panel and an acceptance panel, a weight limit panel and a fixed person and machine system. If the line of sight is not clear or the overhead hoist, a special person should be set up to command or interphone to ensure good signal and no misoperation

the rated load (100%) and overload (125%) tests shall be conducted for the material hoist. The load test shall meet the requirements of the specification

material hoists are construction machines and tools that are only allowed to carry goods and not people, and the quality of operators operating hoists should be strictly required. In addition to setting the machine, staffing, and understanding the performance of the machinery you operate, you should also master the basic technical knowledge and operation system of this type of work, have a strong sense of work, and be able to consciously abide by the safety operation procedures of the hoist. Have the ability of technical standards at the level of this type of work, and achieve the level of "four understandings and three abilities" in practical work, not only understand the principle, structure, performance, purpose, operation, maintenance and troubleshooting of machines and tools. This requires the operators to carry out safety awareness and technical quality training, and only those who have obtained the safety operation certificate of lifting machinery can work with the certificate

the safe use management of material hoists is multifaceted. Only by strengthening human behavior management and material safety performance management, can safety accidents be effectively prevented

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