Removable lifting device- a device connecting the load to the crane. The removable load-handling device is easily removed from the lifting device and disconnected from the load.
Load-handling devices must be manufactured in accordance with the Rules, state standards, projects, technical specifications and other regulatory documents.
The manufacture of load-handling devices and containers must be carried out in accordance with regulatory documents and technological maps. If welding is used, the design documentation must contain instructions for its implementation and quality control.
Load-handling devices (slings, chains, traverses, grips, etc.) after manufacture are subject to testing at the manufacturer, and after repair (except for slings) - at the enterprise where they were repaired. Slings cannot be repaired.
Load-handling devices must be inspected and tested with a load 25% greater than their rated load-carrying capacity.
Information about manufactured load-handling devices must be entered into the Load-Gripping Devices Logbook, which must indicate the name of the device, the passport lifting capacity, the number of the regulatory document (technological map), the certificate number for the material used, the results of welding quality control, and the test results of the load-handling device, if any. were carried out.
Load-handling devices must be equipped with a brand or a firmly attached metal tag indicating the name of the manufacturer (accessory) or its trademark, number, rated load capacity and test date. Load-handling devices, in addition to the brand (tag), must be equipped with a passport, subject to manufacture for another consumer.
During the operation of removable load-handling devices and containers, the owner must periodically inspect them within the following periods:
traverse, tongs and other grips and containers - every month;
slings (except for rarely used ones) - every 10 days;
rarely used removable lifting devices - before putting them into operation.
Inspection of removable load-handling devices and containers must be carried out according to instructions developed by a specialized organization and defining the procedure and methods of inspection, and rejection indicators. Damaged removable load-handling devices identified during the inspection must be removed from work.
The results of the inspection of removable load-handling devices and containers are recorded in the inspection log of load-handling devices.
8.4 Noise in workplaces, its norms and permissible values. Basic measures to reduce noise levels and prevent its harmful effects (SN 2.2.4/2.1.8.562-96, introduced by the Russian State Inspectorate dated May 28, 1998 No. 418).
From a physiological point of view noise is any unwanted, unpleasant sound for human perception.
As a physical phenomenon noise is a wave oscillation of an elastic medium.
Noise levels are usually measured in relative units called decibels.
Noise has an adverse effect on the human body, causing mental and physiological disorders that reduce performance and create preconditions for general and occupational diseases and industrial injuries.
The immediate result of the negative effects of noise is hearing damage and hearing loss. However, noise affects not only the hearing organs. Through the fibers of the auditory nerves, irritation from noise is transmitted to the central and autonomic nervous systems, which leads to serious changes in the internal organs of a person and affects his mental state, causing feelings of anxiety and irritation. Secondary exposure to noise and vibration leads to changes in the cardiovascular system, to functional disorders of the nervous system and, as a result, to irritability, insomnia, and hypertension (deterioration of blood supply to the heart and vasospasm).
In shipbuilding and ship repair, many technological operations are accompanied by intense noise: work using mechanized impact and rotary tools, machine processing of rolled products and parts. Forging and pressing equipment, metal and woodworking machines, fans, compressors, electric and pneumatic machines, and welding converters are noisy. Noise of significant intensity occurs when cutting metal, especially when cutting and cleaning welds in closed ship compartments and rooms.
Whenever the stationary state of a continuous medium is violated at some point in space, disturbances appear that propagate from this point and are called waves. In air, wave motion consists of longitudinal waves diverging in different directions.
There are:
airborne noise, spreading in the air from the place of origin to the place of observation;
structural noise, emitted by the surfaces of oscillating structures of walls, ceilings, partitions and buildings.
Based on their time characteristics, noise is divided into:
permanent, the sound level of which over an 8-hour working day (work shift) changes over time by no more than 5 dBA when measured on the time characteristic of a “slow” sound level meter according to GOST 17187;
non-constant, the sound level of which during an 8-hour working day (work shift) changes over time by more than 5 dBA when measured on the time characteristic of a “slow” sound level meter according to GOST 17187.
Under the influence of a noise source, pressure fluctuations in the air occur. The difference between the instantaneous value of the total pressure in the medium and the average pressure, which is observed in the absence of sound waves, is called sound pressure.
The human ear is capable of assessing not an absolute, but a relative change in sound pressure, therefore the characteristic of constant noise is sound pressure level– relative value, measured in decibels (dB).
The ear of a person with normal hearing distinguishes sound vibrations with a frequency from 16 Hz to 20 kHz. Frequencies below 16 Hz are called infrasonic; above 20 kHz – ultrasonic.
1 Hz– this is one vibration per second.
If the maximum sound pressure level is in the frequency range up to 300 Hz, then noise called low frequency; if in the range 300 ... 800 Hz – mid-frequency, and at a frequency greater than 800 Hz – high frequency.
For the relative logarithmic scale, indicators characterizing minimum threshold for sound perception human ear at frequency 1000 Hz.
Area of greatest sensitivity human ear is located at the frequency 4100 Hz. This vibration frequency is the most unpleasant to the ear; the sound is screeching or grinding, creaking.
Noise frequency more than 500 Hz disturbs workers more than noise of a lower frequency.
Intermittent noise more harmful than permanent.
Sudden intense noise has a negative effect on human performance and nervous system.
Loud noise causes difficulties in assessing distance and time, in recognizing color signals, reduces visual acuity, impairs the perception of visual information, visual reaction at night. This leads to a decrease in labor productivity, as well as an increase in the degree of danger to humans at work.
Another result of noise exposure– masking quieter sounds while the human ear simultaneously perceives two or more sounds of different volumes. Occupational noise can mask audible warning signals of dangerous situations, and the louder the disturbing sound, the more the sensitivity of the human ear changes.
The maximum permissible level (MAL) of noise is the level of a factor that, during daily (except weekends) work, but not more than 40 hours a week during the entire working period, should not cause diseases or health problems detected by modern research methods in in the process of work or in the long term of the life of the present and subsequent generations. Compliance with noise limits does not exclude health problems in hypersensitive individuals.
The permissible noise level is a level that does not cause significant disturbance to a person and does not cause significant changes in the functional state of systems and analyzers that are sensitive to noise.
Infrasound:
permissible sound pressure levels in octave bands with geometric mean frequencies 2, 4, 8 and 16 Hz - according to sanitary standards ( no more than 105 dB); and in the band with a frequency of 31.5 Hz – 102 dB.
Ultrasound:
permissible sound pressure levels at the geometric mean frequency of the one-third octave band equal to 12.5 kHz - should not exceed 80 dB; at a frequency of 16 kHz – 90 dB; 20 kHz – 100 dB; 25 kHz – 105 dB; and in the frequency range 31.5 ... 100.0 kHz - 110 dB.
Permissible levels of ultrasound in areas of contact of the hands and other parts of the operator’s body with the working parts of instruments and installations should not exceed 110 dB.
Noise protection:
When developing technological processes, designing, manufacturing and operating machines, industrial buildings and structures, as well as when organizing a workplace, all necessary measures should be taken to reduce noise affecting people in the workplace to values not exceeding the permissible values indicated in the table:
development of noise-proof equipment;
use of means and methods of collective protection in accordance with GOST 12.1.029;
use of personal protective equipment (PPE) in accordance with GOST 12.4.051.
Areas with sound levels above 80 dB A must be marked with safety signs in accordance with GOST 12.4.026. The administration is obliged to provide workers in these zones with personal protective equipment (PPE) in accordance with GOST 12.4.051.
The enterprise must monitor noise levels in the workplace at least once a year.
7.2. The engineering and technical worker for supervision of the safe operation of lifting machines is obliged to supervise the technical condition and safe operation of lifting machines, removable lifting devices, production containers and take measures to prevent violations of safety rules.
7.3. The engineering and technical worker responsible for maintaining lifting machines in good condition is obliged to ensure:
· maintaining removable lifting devices and production containers in good condition (if maintaining them in good condition is not entrusted to other services);
· Carrying out periodic inspections, maintenance and repairs within the time limits established by the schedule;
· systematic monitoring of the correct maintenance of the inspection log and timely elimination of identified faults;
· personal inspection of lifting devices and containers within the established time limits.
7.4. An engineer and technical worker responsible for the safe performance of work with cranes, pipe-laying cranes, manipulator cranes and other lifting machines is obliged to prevent the use of unmarked, faulty or inappropriate removable lifting devices and production containers in terms of the load capacity and nature of the load.
7.5. Owners of lifting machines and operating organizations must develop methods for correct slinging and hooking loads (Appendix 5 to this Technical Standard), which slingers must be trained to use. A graphic representation of slinging and hooking methods should be handed out to slingers and crane operators or posted at work sites.
7.6. The owner of lifting machines or a specialized organization must develop methods for tying parts and assemblies of machines moved by lifting machines during their installation, dismantling and repair, indicating the devices used, as well as methods for safely tilting loads when such an operation is performed using a lifting machine .
7.7. Lifting machines, removable lifting devices and containers that have not passed inspection and technical certification are to be put to worknot allowed. Faulty load-handling devices, as well as devices that do not have tags (stamps), should not be located in the work areas.FORBIDDENpresence of unmarked and damaged containers at work sites.
7.8. Loading and unloading operations and storage of cargo at bases, warehouses, sites must be carried out according to technological maps, which provide a list of used load-handling devices and graphic images (diagrams) of cargo slinging.
7.9. Loads must be slinged in accordance with slinging diagrams. To sling a load intended for lifting, slings must be used that correspond to the weight and nature of the load being lifted, taking into account the number of branches and their angle of inclination. General purpose slings should be selected so that the angle between their branches does not exceed 90°.
7.10. The connections between the hook of the lifting machine and the suspensions, loops and thimbles of the slings must be reliable. The sling suspension must be secured with a hook latch. The mounting loop must be secured with a latch in the hook link of the sling.
7.11. In order to prevent loads from falling during lifting and moving them by cranes, the following slinging rules should be observed:
· When tying a load, the slings must be applied without knots or twists.
· It is necessary to place shims under sharp corners of metal weights (channels, angles, I-beams). In this case, it is necessary to take into account the location of the center of gravity of the load.
· The sling should be placed under the load in such a way as to prevent it from slipping while lifting the load.
· The load must be tied in such a way that during its movement, the fall of its individual parts is prevented and a stable position of the load is ensured during movement. To do this, slinging of long loads (poles, logs, pipes) must be done in at least two places.
· The ends of a multi-leg sling that are not used for hooking must be strengthened so that when moving the load by crane, the possibility of these ends touching objects encountered along the way is excluded.
layout-grid-mode:line">7.12. The movement of small-piece cargo must be carried out in containers specially designed for this purpose, and the possibility of individual cargo falling out must be excluded.
7.13. When moving a load, load-handling device or container horizontally, it should first be lifted 500 mm above equipment, building structures and other objects encountered along the way.
8. The procedure for inspection and rejection of lifting devices and containers and sling markings
8.1. Engineering and technical workers responsible for maintaining lifting machines in good condition, and persons responsible for the safe performance of work with cranes, cranes and pipe layers, manipulator cranes and other lifting machines, must inspect lifting devices within the following periods:
· slings (except for rarely used ones) - every 10 days;
· traverse, grips and containers - every month;
· rarely used removable lifting devices - before releasing them to work.
8.2. When inspecting rope slings, it is necessary to pay attention to the condition of the ropes, thimbles, hooks, hangers, locking devices, clips, carabiners and their attachment points.
8.3. To assess the safety of using ropes, the following criteria are used (Appendix 7 to this Technical Standard ) :
· the nature and number of wire breaks, including the presence of wire breaks at the end seals, places where wire breaks are concentrated, the intensity of the increase in the number of wire breaks;
· strand break;
· surface and internal wear;
· surface and internal corrosion;
· local reduction in rope diameter, including core rupture;
· deformation in the form of waviness, basket-like shape, extrusion of wires and strands, crushing of strands, creases, etc.;
· damage due to temperature effects or electrical arcing.
8.4. Rejection of sling parts (rings, loops and hooks) must be carried out (Appendix 7 to this Technical Standard):
· in the presence of cracks;
· when the surface of elements wears out or local dents lead to a decrease in cross-sectional area by 10%;
· in the presence of residual deformations leading to a change in the original size of the element by more than 5%.
8.5. The following slings are not allowed for use:
· having the defects specified in paragraphs. 8.3.-8.4.;
· if the marking tag is missing or damaged;
· with deformed thimbles or their wear with a reduction in cross-section by more than 15%;
· having cracks on pressed bushings or when their size changes by more than 10% from the original;
· with signs of rope displacement in the braid or bushings;
· with damaged or missing braids or other protective elements in the presence of protruding ends of the wire at the braiding point;
· with hooks without safety locks.
8.6. The chain sling is subject to rejection if the following defects are found:
· link breakage;
· bending or wear of the hook in the link is more than 10% of the original size; chain link elongation of more than 3% of the original size;
· reduction in the cross-sectional diameter of a chain link due to wear of more than 10%.
8.7. When inspecting grippers, it is necessary to check the condition of the working surfaces in contact with the load. If they have a notch, then blunting or chipping of the teeth is not allowed. The gripper must be rejected if bends, breaks in the arms or wear and damage to the connecting links are detected. Metal traverses consisting of beams, struts, frames and other elements are subject to rejection if deformations with a deflection of more than 2 mm per 1 m of length are detected, cracks in places of sharp bends or changes in the cross-section of welded elements, as well as damage to fastening and connecting links.
8.8. When inspecting containers, you must especially carefully check:
· the appearance of cracks in gripping devices for slinging;
· serviceability of actual devices and lid locking devices;
· absence of defects in welded joints, integrity of markings.
8.9. The container is rejected in the following cases:
· the container is not marked;
· the purpose of the container is not indicated;
· there are faulty sling units;
· the sides are dented or torn;
· there are cracks and other defects in welded joints.
8.10. The results of inspection of removable lifting devices and containers must be recorded in a special journal.
8.11. At all sites where the Company's work is carried out, by decision of the site management, the method of color coding slings can be used. This method provides a more accurate accounting of the operating life of the slings before the next monitoring of their condition. Encoding is carried out in accordance with the following rules:
· All slings must be inspected one week prior to the color code change date.
· Slings that are not color coded are not allowed to be used at TNK-BP work sites.
· Slings that successfully pass periodic inspection receive the appropriate color coding and are put into operation.
· On usable slings, the color coding must be changed within one week prior to the color coding change date.
Changing the color coding without first inspecting the slings and discarding unsuitable ones can lead to extremely serious consequences. Such actions are unacceptable and may result in severe disciplinary action.
· The previous color coding must be completely removed or painted over. Lifting devices that have too many visible residual marks from previous color codes must be taken out of service until this requirement is met.
· Posters indicating the current color coding must be displayed in prominent places at all work sites/facilities.
· The validity period of each color coding of lifting devices is determined at 6 months and the change date is set at February 14 and August 14 of each year;
· The total reuse time for each marking color is 18 months.
· The color coating should be applied to the slings by painting them in those places that are always visible and where the color is least likely to wear off.
· Marking soft/fabric slings by dyeing the fibers is not allowed, since dyeing may lead to damage to the integrity of the fibers. Soft/fabric slings are marked by tying tags of the corresponding color to those sections of the slings that are least susceptible to deformation/damage
The choice of encoding color should be made using the following table
Year | Jan. | Feb. | March | Apr | May | June | July | Aug. | Sep. | Oct. | Nov. | Dec |
2008 | 14 |
Figure 1.1 – Steel rope design
The wires are intertwined with each other and form a strand. Several strands, also intertwined with each other and located on the central core, form the rope itself. To protect against corrosion, ropes are lubricated during the manufacturing process with rope lubricants Elascon, Torsiol, Nirasten, etc.
The rope core, made in most cases from hemp, gives it greater elasticity and serves as a lubricant accumulator. Ropes intended for work in hot shops have a core in the form of an asbestos cord or strands of steel wires. The core serves as an internal support and shock absorber for the strands and the rope itself as a whole. It must resist the radial pressure of the strands when the rope is loaded, preventing its transverse deformation. The manufactured ropes are lubricated on the outside with an anti-corrosion protective lubricant and wound onto drums or laid in coils.
Classification of steel ropes
Steel ropes have a large number of types and designs and differ in purpose, type of strand laying, and combination of laying directions. Not all ropes produced by industry can be used on cranes. As research and operating experience show, the number of crane rope designs can be limited to 8-10. Special treatment of rope wire ensures its high mechanical properties. Thus, the marking group (temporary tensile strength) of the wires varies in a wide range of 1372...2352 MPa. Depending on the number of wires in a strand, strands in a rope, their design and shape, the combination of lay directions of rope elements, the presence and type of core and other factors, a variety of structural forms of steel wire ropes () are possible.
Table 1.1 – Classification of steel ropes
| Signs by which ropes are divided | Designation |
|---|---|
| 1. By purpose: | |
| cargo-human | GL |
| freight | G |
| 2. According to the brevity of the lay: | |
| single - the rope is made of a central wire, around which the wire is wound along a helix in several layers | |
| double - made from single lay strands twisted around a core | |
| triple - made from double lay strands twisted around a core | |
| 3. By core type: | |
| hemp | |
| asbestos | |
| steel (used at high temperatures, to increase breaking strength - strand or double lay rope) | |
| 4. According to the mechanical properties of wires: | |
| highest grade - for GL type ropes | IN |
| first grade - for all ropes | I |
| second brand (with consumer consent) | II |
| 5. According to the type of wire surface coating: | |
| made of light-colored uncoated wire – for light working conditions | – |
| made of galvanized wire for aggressive working conditions | WITH |
| made of galvanized wire for harsh aggressive working conditions | AND |
| made of galvanized wire for particularly harsh aggressive operating conditions (corrosion-resistant, but more expensive) | coolant |
| 6. In the direction of curl of the strands: | |
| right – preferential (lay from right to left down) | – |
| left - left to right down | L |
| 7. According to the combination of laying directions of wires in strands and rope strands: | |
| cross - mainly used: the laying directions of wires in strands and strands are different, they do not unwind | – |
| one-sided - the laying directions of wires in strands and strands are the same, more flexible | ABOUT |
| 8. According to the laying method: | |
| non-unwinding – with strand compression | N |
| unwinding | R |
| 9. By type of lay: | |
| with point contact of wires of the same diameter - the winding angles of the wires in different layers are not the same, which increases the pressure between the wires and increases their wear, but they do not unwind under load | TK |
| with linear contact of wires - the winding angles of wires in different layers are the same, more flexible, durable, service life is 30-40% higher than TC | OK |
| with linear contact of wires of the same diameters in the upper layer of the strand | LK-O |
| with linear contact of wires of different diameters in the upper layer of the strand - have better cross-section filling | LK-R |
| with linear contact of wires of different and identical diameters along individual layers of the strand | LK-RO |
| with point and linear contact of wires in strands | TLC |
Only double lay, six-strand, and cross ropes are used at the PMG. Externally, a cross lay rope differs in that the wires on its surface are located parallel to the axis of the rope. The wires of a one-way lay rope are located at an angle to its axis.
Rope markings
The following structural diagram of the symbol for steel ropes has been established:
Where:
- Product name.
- Rope diameter, mm.
- Designation of the purpose of the rope (GL, G).
- Designation of the brand (mechanical properties) of wires (B, I, II).
- Designation of the type of wire surface coating.
- Designation of the direction of laying of strands (-, L).
- Designation of the combination of laying directions of rope elements (-, O).
- Designations for the rope laying method (H, P).
- Marking group, MPa.
- Designation of the standard for the selected type of rope.
If there is no designation of any feature of the rope, then in the record of the rope characteristics the symbol of this feature is omitted.
In addition, ropes differ in rope diameter, marking group (1372, 1470, 1568, 1666, 1764, 1862, 1960, 2156, 2254, 2352 MPa), the number of wires in the strands and the number of strands in the rope.
An example of the designation and characteristics of a steel rope with a diameter of 11.5 mm, cargo, made of grade I material with a light-colored surface of the wires, with right-hand lay of strands, cross lay of rope elements, non-unwinding, from wires of the marking group 1568 MPa, according to GOST 3077-80:
Rope 11.5-G-I-N-1568 GOST 3077-80
In this entry, indications that the surface of the wires is light, the lay of the strands is right-handed, and the combination of the lay of the wires in the strands is cross-shaped are omitted as not having a designation. This means that the rope is ordered from light wire, right-hand cross lay.
Methods for fastening rope ends
The loop at the end of the rope when attaching it to the crane, as well as the loop of the sling associated with rings, hooks or other parts, must be made:
Figure 1.3 – Methods for making a loop at the end of a rope: a – braiding the free end; b – use of a wedge bushing; c – installation of screw clamps; d – filling in the conical bushing; 1 – thimble; 2 – wedge; 3 – wedge bushing; 4 – screw clamp; 5 – working branch; 6 – bracket; 7 – bar; 8 – nut
Housings, bushings and wedges should not have sharp edges on which the rope can rub. The wedge bushing and wedge must be marked according to the diameter of the rope.
The number of rope punctures with each strand during braiding must correspond to those indicated in Table 1.2.
Table 1.2 – Number of rope punctures by strands during braiding
The last puncture of each strand should be made with half the number of its wires (half the cross-section of the strand). It is allowed to make the last puncture with half the number of strands of rope.
The design of the clamps must comply with regulatory documents.
The number of clamps is determined during design taking into account the diameter of the rope, but must be at least three. The spacing of the clamps and the length of the free end of the rope behind the last clamp must be at least six rope diameters. The clamping brackets must be installed on the side of the free end of the rope.
2. Round link load chains
For the manufacture of removable load-handling devices, round-link load chains are used.
They are made from structural steel grades StZ and steel 20 by forge-forge or resistance welding.
To splice chains, welding or special connecting links are used. The chain is characterized by the diameter of the bar d, from which it is made and the chain pitch R ().
Figure 2.1 – Load chain: P – step; d – diameter; b – outer width
3. General information about lifting devices
Removable (hinged) load-handling devices(GU) are used to connect the transported cargo with the load body of the crane. They are not an accessory of the faucet and are an independent reusable product; such GIs are called inventory.
The technological operation of connecting a load with a crane hook is called slinging cargo, and its inverse operation is slinging.
Modern removable GIs must satisfy the following basic requirements:
- simplicity of design with high operational reliability;
- high manufacturability and practical application;
- high strength with small dimensions and weight;
- strict compliance with the parameters of the transported cargo;
- low cost;
- convenience and speed of cargo slinging.
Slings They are among the simplest lifting devices in design and are flexible elements with end fastenings and gripping elements of various designs.
Slings come in the following types (Figure 3.1):
- rope, made from steel ropes;
- chain, made from round link chains;
- textile, made from synthetic ropes and tapes.
All of these slings have their advantages and disadvantages.
Currently in Russia rope slings- the most common. For the manufacture of rope slings, double lay, cross lay ropes with an organic core (OC) of the following structures are used: 6×19(1+6+6/6)+1 OS LK-R, 6×36(1+7+7/7+14)+1 OS LK-RO.
To move loads with temperatures up to 400 °C, ropes with a steel core are used.
Advantages of rope slings:
- high strength;
- ease of manufacture, low cost;
- ease of operation;
- are not destroyed instantly;
- are not afraid of dynamic load.
- if slinging is incorrect, the surface of the load can be damaged; it is necessary to install chocks under the sharp edges or ribs of the load;
- with a large rope diameter, the slings are relatively rigid, have quite a lot of weight and, as a result, are inconvenient to use;
- ropes are lubricated and may contaminate the cargo;
- broken ends of the wires damage your hands.
Figure 3.2 – Disadvantages of rope slings
Steel thimbles must be installed in the loops of rope slings ( thimble– round or oval steel cage with a groove on the outer surface) (Figure 3.3).
They produce single- and multi-branch rope slings equipped with hanging and load-handling links. The hanging links are used to hang the sling on the crane hook, and the load-handling links are used to attach the slings to the load.
Based on the number of branches, slings are divided into rope slings:
- single-branch (1SC);
- two-branch (2SC);
- three-branch (ZSC);
- four-branched (4SC).
There are universal rope slings: straight, type USK1, and closed(ring) type USK2, which do not have gripping devices and are used, as a rule, for slinging loads that are not equipped with special gripping devices (loops, brackets, eyes, eye bolts, bosses on the body, etc.) (). In these cases, slinging of the load is performed in a girth or “boa constrictor” manner. These slings are classified as lightweight, so thimbles are not placed in rope loops.
Table 3.1 – Types of rope slings
| Name | Designation | Appearance |
|---|---|---|
| USK1 |  |
|
| USK2 |  |
|
| SK1 | ||
| SK2 | ||
| Three-legged rope sling | SK3 | |
| SK4 |  |
The designation of the sling indicates its type, load capacity and length. For example, 2SK-1.6/1000 stands for two-branch rope sling with a lifting capacity of 1.6 tons and a length of 1000 mm.
Chain slings are made from chains and chain components of strength class 8. It is possible to manufacture chain slings with various end elements (hooks, staples, etc.).
Area of application: metallurgical and chemical enterprises, when transshipping dangerous goods and on portal cranes.
Advantages of chain slings:
- workable at high temperatures;
- are not afraid of sharp edges of the load;
- compact, easy to fold;
- durable;
- performance in aggressive environments.
Essential disadvantages of steel chains are:
- large mass;
- the possibility of sudden rupture due to the rapid opening of formed cracks;
- the need for careful daily monitoring of the condition (wear) of chain links.
- do not allow the application of dynamic loads;
- Defects in the metal of chain links are difficult to detect.
Similar to rope slings, there are single-branch chain slings (1SC), two-branch (2SC), three-branch (ZSC), four-branch (4SC) and universal (USC) ().
Table 3.2 – Types of chain slings
| Name | Designation | Appearance |
|---|---|---|
| 1SC | ||
| Double chain sling | 2SC |  |
| Three-legged chain sling | 3SC | |
| 4SC |  |
|
| USC |
Textile slings there are ():
- branch:
- 1ST;
- universal:
- STP (textile loop sling);
- STK (textile ring sling);
- STKk (round-strand textile ring sling).
Table 3.3 – Types of textile slings
| Name | Designation | Appearance |
|---|---|---|
| STP |  |
|
| STK |  |
|
| 1ST | ||
| 2ST |  |
|
| Three-branch textile sling (ribbon) | 3ST | |
| 4ST |  |
|
| STS |
Synthetic materials are used to make textile slings: polyester, nylon, polypropylene. Textile tape slings are sewn from flat woven tape. Round strand slings STKk consist of many endless circular polymer fibers enclosed in a protective casing (sleeve). In addition to the most common types listed, textile slings and other structures are produced.
Advantages of textile slings:
- textile slings are much lighter than metal slings of similar load capacity;
- flexibility and absence of deformation;
- personnel safety when working with textile slings;
- high wear resistance;
- compactness, ease of storage and use;
- ease of operation;
- due to the fact that textiles are much softer than metal, it guarantees complete safety of the goods being moved without the use of special protective devices (at the same time, round-strand textile slings make it possible to move loads not only of large load-bearing capacity, but also quite fragile ones).
Disadvantages of textile slings:
- cannot be used in open fire;
- without a special coating, they are not suitable in alkaline and acidic environments;
- cannot be exposed to ultraviolet radiation (open sun) for a long time, since artificial fibers lose their qualities (therefore, textile slings should be stored in a room protected from light).
Multi-leg slings used for lifting and moving building parts and structures that have two, three or four attachment points. They are widely used for slinging building elements (panels, blocks, trusses, etc.) equipped with loops or eyes. When using a multi-leg sling, the load must be transferred to all branches evenly, which is ensured by auxiliary connections.
Universal slings used when lifting loads that cannot be tied with conventional slings (pipes, boards, rolled metal, apparatus, etc.).
Used for the manufacture of slings hanging links following types ():
- RT (detachable triangular);
- T (triangular);
- O (ovoid);
- Ov (oval).
Figure 3.4 – Sling links: a) RT type; b) type T; c) type O; d) Ov type; e) hooks; e) carabiner; g) bracket: 1 – lock; 2 – pin
Hooks are usually used as grips, but staples, carabiners and other products can be used. Sling hooks must have a safety lock that prevents the hook from falling out of the loop when hooking a load. The bracket for connecting to the sling and slinging parts of the load has a removable pin.
4. Tara
Tara are various types of containers and packaging in which goods are transported. The purpose of the container is to make the cargo convenient for movement and to ensure conditions for its qualitative and quantitative safety.
The container must be designed for the cargo for which it is intended to be transported. The container capacity must prevent the possibility of overloading the crane. After production, the containers are carefully inspected.
If the container is found fit for use after manufacturing, it must be provided with a plate or an inscription indicating the number, dead weight, load capacity, name of the workshop, test date, and purpose of the container.
Frequency of inspections of lifting containers:
- the person responsible for the safe performance of work on moving goods by cranes - every shift;
- the person responsible for the good condition – once a month;
- slinger - before use.
During inspection, special attention should be paid to the integrity of welded and riveted joints, as well as to the serviceability of fastening of towbars, hooks, loops, and axles.
The container is considered unusable, if it has:
- deformation of sheets, walls, bottoms;
- violation of the integrity of welded and riveted joints, cracks and tears in the walls;
- wear of trailers more than 10% of the original diameter;
- there is no marking (data plate), even if the container is intact.
If at least one sign of rejection is detected, the container must be freed from the load and delivered to the repair site.
It is prohibited to use containers that are faulty or for purposes other than their intended purpose.
Let's consider types of containers:
What are the requirements for the manufacture and labeling of containers?
The containers must be manufactured in accordance with technological maps or individual drawings.
After manufacturing, the container must be subject to technical certification (inspection); the container is not subject to testing with a control load.
On containers, with the exception of special technological ones, must be indicated ():
- purpose of the container;
- number;
- dead weight;
- the largest mass of cargo for which it is intended to be transported.
Figure 4.5 – Container marking
How to fill containers correctly?
The container should be filled only with the material for which it is intended. Filling containers with material with a higher specific gravity may cause overload of the crane or destruction of the container.
Bulk and small-piece cargo should be located no higher than 100 mm from the level of the sides (). To prevent overloading of the container, a fill line must be marked on its side.
Figure 4.6 – Rules for filling containers
Semi-liquid and liquid cargo should fill no more than 3/4 of the container volume.
5. Safety requirements
The main requirements for the design and manufacture of lifting devices and containers are:
- strength and reliability of the design of the load-handling device and container;
- minimum dead weight compared to the weight of the lifted load;
- ease of maintenance and handling;
- simplicity of design;
- ensuring the safety of captured cargo;
- compliance with the peculiarities of technological processes and work projects, further automation of the process of capturing and releasing cargo (work according to a given program without the participation of service personnel).
The manufacture of load-handling devices and containers must be carried out by enterprises and specialized organizations that have permission from Rostechnadzor authorities.
The production of load-handling devices and containers must be carried out in accordance with regulatory documents and technological maps; after production, they are subject to testing at the manufacturer, and after repair (except for slings) - at the enterprise where they were repaired. Slings cannot be repaired.
Load-handling devices must be inspected and tested with a load that is 25% greater than their rated load-carrying capacity.
Information about manufactured lifting devices must be entered in “Logbook of records of load-handling devices”, which must indicate the name of the device, the certified lifting capacity, the number of the regulatory document (technological map), the certificate number for the material used, the results of welding quality control, and the test results of the load-handling device.
Load-handling devices must be equipped branded or firmly attached metal tag indicating:
- numbers;
- nameplate carrying capacity;
- test dates.
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Figure 6.1 – Lifting a load using traverses |
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The use of inclined slings for lifting long structures and heavy equipment - beams, trusses, frames, apparatus, etc. – leads to a loss of useful lifting height of the crane, as well as to the occurrence of significant tensile forces in the sling itself, compressive forces in the lifted element and bending forces in the mounting loops. Slings combined with traverses do not have these disadvantages and are used for slinging loads 12 m or more in length.
There are many different modifications of traverses, which is due to the wide variety of building structures and technological equipment.
Lifting crossbeams have a design determined by the geometry of the load, the technical capabilities of the crane and the operating conditions of the device itself. Traverses are made of steel. According to their design, they are divided into planar () and spatial ().
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Figure 6.3 – Spatial traverses |
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The former are produced in the form of a beam, the latter can be T-shaped, H-shaped, in the form of a triangular or rectangular truss.
Used to handle a range of loads balancing beams, with holes for brackets hung on the hooks of cranes and providing changes to the arms ().
Figure 6.4 – Universal beam crossbar: 1 – suspension; 2 – tension rope; 3 – earring; 4 – bracket; 5 – rope (balance) sling; 6 – roller; 7 – beam
Balancer beams are used when working with loads whose attachment points are located unevenly or at different levels.
Grips are the most advanced and safe load-handling devices, the main advantage of which is the reduction of manual labor. Grippers are used in cases where it is necessary to move loads of the same type. Due to the wide variety of loads being handled, there are many different gripper designs available. Most of them can be classified into one of the following types.
Table 9.2 - Rope rejection standards depending on surface wear or corrosion
| Reduction in wire diameter as a result of surface wear or corrosion, % | Number of wire breaks, % of the standards specified in |
|---|---|
| 10 | 85 |
| 15 | 75 |
| 20 | 70 |
| 25 | 60 |
| 30 or more | 50 |
- absence of a label (tag) or inability to read information about the sling;
- knots on the sling;
- transverse cuts or tears in the tape;
- seam rupture at the base of the loop;
- through damage or burns to the supporting layer;
- damage to more than 10% of the cross-sectional area of the tape;
- delamination of tape threads, etc.
Figure 9.4 – Signs of rejection of textile slings
Signs of rejection seizures:
- absence of a brand or tag;
- dullness or chipping of notch teeth on working surfaces in contact with the load;
- bends and kinks of levers;
- wear of hinges.
Metal traverses, consisting of beams, struts, frames and other elements, are subject to rejection if deformations with a deflection of more than 2 mm per 1 m of length are detected, cracks in places of sharp bends or changes in the cross-section of welded elements, as well as damage to fastening and connecting links.
Most lifting operations are directly related to the use of special industrial products called slings. These elements for carrying out operations for lifting/lowering various objects are produced in strict accordance with state standards and undergo appropriate certification at specialized enterprises. Slings, their varieties and designation rules will be discussed in this article.
general information
Marking of slings is mandatory. Each of these can be based on a chain or element created on the basis of special matter. The use of slings is carried out in almost all sectors of the national economy: in construction, in the manufacturing sector, in agriculture, navigation, etc.
Rope type slings
These slings are able to withstand extremely low temperatures (down to -40 and very high temperatures (within 400 degrees). The rope itself consists of many metal wires, securely woven together using a special technology.
The configuration of rope slings makes it possible to easily diagnose the degree of their wear during operation, thereby preventing the possibility of sudden rupture of these devices. In addition, the wire steel rope has the ability to smooth out emerging dynamic loads and therefore has a very long life of safe operation.
The marking of rope slings provides the following alphanumeric designations:
- 1SK - the sling has one branch.
- 2 SK is a two-branch model, widely used in production workshops or warehouses.
- 4 SK - four branches of the sling are attached to a special ring. This design of the lifting element has proven itself well on construction sites, where it is often necessary to move huge slabs and blocks.
- VK - the ends of this type of sling are sealed either by crimping or braiding.
- SKK - ring version.
- SKP - loop version.
Operating rules
Sling markings are just the tip of the iceberg. You should always remember the rules for using lifting products. To do this, you must strictly comply with the following requirements:
Chain models
To handle loads with sharp edges, it is best to use chain slings. These devices are made from steel links, which in turn are connected to each other by welding. The resulting design has high strength, reliability, flexibility and ease of use. The chain sling is also good because it is not afraid of high or low temperatures, exposure to acid or open fire. However, compared to its rope counterpart, the chain version will have much more weight.
The marking of slings made from chain is as follows:
- 1 SC - single-branch option.
- 2 SC - the two-leg design of the sling eliminates the breaking of chain links.
- 4 SC - the so-called spider. Four-legged sling used for handling non-standard shaped loads.
- VCC is a chain branch that is a spare part for sling repairs, but it can also be used as an independent lifting element.
- USC - ring version or universal.
Features of the designation
Modern requirements for the marking of slings state that the tags attached to them must contain the following information:
- View. This implies an indication of the material from which the sling is made and the number of its branches.
- Load capacity indicator (in tons).
- Length in millimeters.
- The serial number assigned to the sling at the enterprise and indicated in a special journal.
- Date of testing of the lifting element at the factory.
- Names of the manufacturer.
The production and marking of slings stipulates that tags for chain and rope slings must be made of metal - stamped alloy steel. All the required information is applied to them using a shock or impact-point method.
Metal tags are not hung on the textile sling, but vinyl sewn-in copies are used. Data on such tags is applied using indelible ink through thermal printing.
When making braided rope slings, the tag is woven directly into the body of the product. If the sling is pressed, then the tag is attached to a special small loop.
Chain products are supplied with a tag using a clamp on a hanging link.
Textile models
A distinctive feature of these flexible load handling devices is their great versatility.
The marking of textile slings has a similar principle to chain and rope versions and provides for the designation of the load capacity, length, type of loop and type on the label.
In general, there are two main designations:
- STK - stands for textile ring sling. It can be made from one layer or from several.
- STP - textile sling. It can also be single-layer or multi-layer.
Nuances of production and testing
The requirements for the manufacture, testing and marking of slings state that the safety margin of the steel rope in relation to the load of each branch must be at least 6.
Chain slings must be created on the basis of exclusively round-link chain. The safety factor of such slings should be maintained at least 4.
When calculating and producing slings based on hemp, cotton or synthetic material, it is important to adhere to a safety factor of at least 8.
It is important to know that, regardless of the type of sling, they cannot be repaired, and after production they must certainly be tested with a load that is 25% greater than what is stated in the passport.
Slings (markings, their decoding is given above in the article) in the case of individual production must undergo mandatory testing of all their elements. If they are produced en masse, then at least 2% of copies from each batch of produced elements are subject to inspection, but at least two pieces.
When performing static tests of slings, the inspector must visually verify that there is no residual deformation, cracks on the surface, or displacement of the rope in its fastenings.
Moving loads using slings
To transport objects with sharp edges using rope-type slings, it is necessary to place special spacers made of wood, rubber, or metal between the slings and the edges of the load, which serve to prevent damage to the rope.
If a chain sling is used, it is extremely important to avoid any bending of the links on the edges of the load being moved.
Heads of organizations operating cranes are obliged to ensure that they are kept in good condition and safe working conditions by organizing proper inspection, inspection, repair, supervision and maintenance.
For these purposes there should be appointed(from PB 10-382-00):
1. Engineering and technical personnel supervision for the safe operation of cranes, lifting devices and containers;
2. Engineer responsible for content lifting cranes in good condition;
3. person responsible for safe production works with cranes.
Exploitation SGZP that have not passed technical examination, not allowed.
· Rejected SGPPs should not be located at work sites.
· It is prohibited to repair slings by the owner.
· Forced drying of slings by any means is not allowed.
· It is prohibited to use slings in environments containing abrasive materials - cement, concrete.
Storage.
· SGPP should be stored in special rooms and under sheds.
· Individual gas supplies with large overall dimensions are allowed to be stored in open storage areas with fencing.
· Storage must be in accordance with the manufacturer's operating instructions.
Care:
· inspection;
· cleaning of cargo residues and dirt;
· lubrication (if necessary);
· replacement of faulty fasteners;
· adjustment;
· painting or galvanizing (if necessary) in accordance with the requirements of technical documentation.
BASIC POINTS OF THE INSTRUCTIONS
FOR SLINGERS SERVICING GZP CRANES
General provisions
1. It is allowed to carry out slinging and tying of loads faces,
· not younger than 18 years of age;
· have passed a medical examination;
· trained and passed qualification exams;
· received a certificate.
2. The slinger must have with him while working certificate , which should contain:
· photograph of the owner;
· signatures of the chairman of the qualification commission and the Rostechnadzor inspector.
3. Permission to work independently is issued by order by enterprise.
4. Repeated testing of the slinger’s knowledge by the qualification commission is carried out (from PB 10-382-00):
periodically, at least 1 time V 12 months;
· when an employee transfers to other place of work;
· on demand Engineers to supervise the safe operation of cranes or an inspector from the State Mining and Technical Supervision Authority.
Repeated knowledge testing should be carried out within the scope of the production instructions. Participation of the State Mining and Technical Supervision Inspector in repeated testing the knowledge of service personnel not necessary, in the work of the qualification commission at primary certification of slingers Necessarily.
5. The slinger obeys in his work the person responsible for the safe operation of cranes.
7. Slinger and crane operator together service the crane, make decisions independently and carry responsibility each for his own plot: crane operator - for operating the crane, slinger - for slinging the load, but the instructions from the crane operator to the slinger are mandatory.
8. To give signals The crane operator must be assigned senior slinger