Hoisting operations are mostly directly related to the use of special industrial products called slings. These elements for carrying out operations on lifting / lowering various items are made in strict accordance with state standards and are certified at narrowly specialized enterprises. About slings, their varieties and designation rules will be discussed in this article.
general information
Marking slings is mandatory. Each of these lifting devices can basically have a cable, rope, chain or element created on the basis of special material. The use of slings is carried out in almost all sectors of the economy: in construction, in the manufacturing sector, in agriculture, shipping, etc.
Rope-type slings
These slings are able to withstand extremely low temperatures (up to -40 degrees Celsius) and very high rates (within 400 degrees). The rope itself consists of many metal wires, reliably interwoven with each other using special technology.
The configuration of rope slings allows you to easily diagnose the degree of wear during operation, which prevents the likelihood of a sharp rupture of these devices. In addition, the steel wire rope has the ability to smooth out the emerging dynamic loads and therefore has a very long term of safe operation.
Marking of rope slings provides the following alphanumeric designations:
- 1SK - the sling has one branch.
- 2 SK - two-branch model, widely used in production shops or warehouses.
- 4 SK - four branches of the sling are fixed on a special ring. This design of the lifting element is well established on construction sites, where it is often necessary to move huge slabs and blocks.
- VK - the ends of a sling of this type are sealed with either crimping or braiding.
- CCM - ring option.
- SKP - loop version.
Terms of Use
Marking slings is just the tip of the iceberg. You must always remember the rules for using lifting products. To do this, strictly observe the following requirements:
- The condition of the slings is checked at the time indicated in their technical passport.
- It is strictly forbidden to use a sling if there are any traces of mechanical damage, there is no tag if a scheduled inspection was not carried out.
- In the case of the use of the sling at a temperature of more than 1250 degrees Celsius, its carrying capacity will decrease by 25%.
- Strictly follow the scheme of cargo sling in order to ensure the safety of operating personnel.
- Do not allow movement or sliding of the sling along the load to be lifted during its movement.
Chain models
For servicing goods with sharp edges, it is best to use chain slings. These devices are made of steel links, which, in turn, are connected to each other by welding. As a result, the resulting design has high strength, reliability, flexibility and ease of use. A chain sling is also good because it is not afraid of high or low temperature, exposure to acid or open flame. However, in comparison with the cable counterpart, the chain version will have much more weight.
The marking of the slings created from the chain is as follows:
- 1 SC - one-branch option.
- 2 SC - two-branch design of the sling eliminates the breaking of chain links.
- 4 SC - the so-called spider. Four-strand sling used for working with non-standard shaped loads.
- VVTS - a chain branch, which is a spare part for the repair of the sling, however, it can also be used as an independent load-lifting element.
- USTs - ring version or universal.
Designation Features
Modern requirements for the marking of slings say that the tags attached to them must have the following information:
- View. The indication of the material of which the sling is made and the number of its branches is implied.
- Capacity indicator (in tons).
- Length in millimeters.
- The serial number assigned to the sling at the enterprise and indicated in a special journal.
- The date the load cell was tested at the factory.
- Names of the manufacturer.
The manufacture and marking of slings provides that tags for chain and rope slings are necessarily made of metal - stamped alloy steel. All the required information is applied to them by shock or shock-point method.
Metal tags are not hung on a textile sling, and vinyl sewn-in copies are used. The data on such tags are applied using indelible ink through thermal printing.
In the manufacture of braided rope slings, the tag is woven directly into the body of the product. If the line is pressed, then the tag is fixed on a special small loop.
Chain products are supplied with a tag using a clamp on a suspension link.
Textile models
A distinctive feature of these flexible devices for working with goods is their great versatility.
Labeling of textile slings has a similar principle with chain and rope options and provides for the designation of a label on the load capacity, length, type of loop and type.
In general, there are two main notations:
- STK - stands for textile ring sling. It can be made of one layer or several.
- STP - textile sling. It can also be single-layer or multi-layer.
The nuances of production and verification
The requirements for the manufacture, testing and marking of slings say that the safety margin of a steel rope with respect to the load of each branch should be at least 6.
Chain slings should be created on the basis of exclusively round link chains. The safety factor of such slings should be maintained at least 4.
When calculating and manufacturing 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 can not be repaired, and after manufacturing they must certainly be tested with a load exceeding 25% of their declared in the passport.
Slings (marking, decoding them are given above in the article) in the case of individual production must undergo a mandatory check of all its elements. If lifting devices are mass produced, then at least 2% of copies from each batch of manufactured items are tested, but at least two pieces are required.
During the static tests of the slings, the inspector must visually finally verify that there is no permanent deformation, cracks on the surface, rope displacement in its mountings.
Moving cargo using slings
To transport objects with sharp edges using rope-type slings, it is necessary to place special spacers made of wood, rubber, metal between the slings and cargo ribs, which serve to prevent damage to the rope.
If a chain sling is used, it is extremely important to avoid any kink of the links on the edges of the transported load.