Rejection rates for steel rope slings

1. 1. The rejection of slings from steel ropes (cables) in operation is made according to the number of wire breaks over the length of one lay step. The rejection of ropes made of wires of the same diameter is carried out according to the data in Table. 1 and figure (hereinafter figures are not shown).
2. 2. The pitch of the rope is determined as follows. On the surface of a strand (see figure), a mark is applied (point A), from which as many strands are counted along the central axis of the rope as there are in the section of the rope (for example, 6 in a six-strand rope), and on the next strand after counting ( in this case, on the seventh), a second mark is applied (point B). The distance between the marks (points A and B) is taken as the pitch of the rope.
3. Multi-strand cables (for example, a rope 18 x 19 = 342 wires with one organic core) have 6 strands in the inner layer and 12 in the outer layer. The lay step in this case is determined by the number of strands in the outer layer.
4. 3. Rejection of a rope made of wires of various diameters, construction 6 x 19 = 114 wires with one organic core is made according to the data given in the first column of the table. 1, and the number of breaks as a rejection rate is taken as conditional. When calculating, a break in a thin wire is taken as 1, and a break in a thick wire is taken as 1.7.
5. For example, if there are six breaks of thin wires and five breaks of thick wires on the length of one rope lay with an initial safety factor of up to 6, then the conditional number of breaks is 6 x 1 + 5 x 1.7 = 14.5, i.e. more than 12 (see table. 1), therefore, the rope is rejected.
6. 4. The number of wire breaks along the length of one lay step as a criterion for rejecting a rope, the design of which is not indicated in table. 1, is determined based on the data placed in this table for the rope closest in the number of strands and the number of wires. For example, for a rope of construction 8 x 19 = 152 wires with one organic core closest to the table. 1 is a rope 6 x 19 = 114 wires with one organic core. To determine the sign of rejection, the number of breaks at one lay step for a rope 6 x 19 = 114 wires with one organic core should be multiplied by a factor of 96/72 = 1.33, where 96 and 72 are the number of wires in the outer layers of strands of one and the other ropes. The number of wires in the outer layers of the strands is determined by the standard for the respective rope or by counting.
7. Table 1
8. NUMBER OF WIRE BREAKING ON THE LENGTH OF ONE PITCH OF THE ROPE WHEEL, AT WHICH THE ROPE SHOULD BE DISABLED
9. The initial factor of the safety factor at the ratio established by the Rules Religious One-sided Relic One-sided Religious One-sided Religious One-sidedUp to 6 12 6 22 11 36 18 36 18

   Rope construction
   6 x 19 = 114		6 x 37 = 222		6 x 61 = 336		18 x 19 = 342
   		and one organic core		and one organic core		and one organic core
   Rope lay

10. table 2
11. ROPE DISABLING RULES DEPENDING ON SURFACE WEAR OR CORROSION
12. ┌─────────────────────────────────┬─────────────── ──────────────── │ │ │ tab. 1 │ ├────────────────────────────────┼───────────── ──────────────────┤ │10 │85 │ │15 │75 │ │20 │70 │ │25 │60 │ │30 and more │50 │ └──── ─────────────────────────────┴──────────────────── ──────────┘
13. 5. If the rope has surface wear or corrosion of the wires, the number of breaks at the lay step as a criterion for rejection should be reduced in accordance with the data in Table. 2. In case of wear (or corrosion), reaching 40% or more of the original diameter of the wires, the rope should be rejected.
14. Determination of wear or corrosion of wires by diameter is carried out using a micrometer or other instrument that provides sufficient accuracy. For this, the end of the wire is bent at the point of breakage in the area of ​​greatest wear. The remaining thickness of the wire is measured at the folded end after the preliminary removal of dirt and rust from it.
15. 6. When the number of wire breaks on the length of one lay step is less than indicated in table. 1 or as determined by the instructions in clauses 3, 4, 5 of this Appendix, as well as in the presence of surface wear of the wires without breakage, the sling can be allowed to work, subject to careful observation of its condition during periodic inspections with recording the results in the inspection log ...
16. 7. If a broken strand is found in the sling, the rope is not allowed for further work.
17. Note. The norms for rejecting the ropes of hoisting machines are given in the "Rules for the construction and safe operation of hoisting cranes", approved. Gosgortekhnadzor of Russia 12/30/92.

According to the requirements of "Interindustry rules on labor protection during loading and unloading and placement of goods" POT RM-007-98, slingers must inspect the slings before using them. Engineering and technical workers responsible for the maintenance of hoisting machines in good condition and persons responsible for the safe performance of work with cranes and other hoisting machines must inspect slings every 10 days, and rarely used removable lifting devices before putting them into operation. When inspecting slings, you must pay attention to the condition of the rope slings, hooks, hangers, the place where the sling is braided and the condition of the crimping points with bushings.

Slings are not allowed to work, in which:

- there is no (or damaged) tag or passport for the sling;
- knots, twisting, kinks and creases on the ropes;
- the number of visible breaks of the outer wires of the rope exceeds that indicated in the table:

Reduction of the rope diameter due to wear or corrosion by 7% or more (even in the absence of visible breaks);
- reduction of the diameter of the outer wires due to wear or corrosion by 40% or more;
- reduction of the rope diameter by 10% due to damage to the core;
- breakage of at least one strand;
- extrusion of the core;
- damage due to exposure to temperature or electric arc discharge;
- deformation of the thimble or wear of its section by more than 15%;
- cracks on the crimping sleeve or changes in its size by more than 10% of the original;
- there are no safety locks on hooks or other gripping elements.

On suspensions, links, hooks and other elements of the sling, the following is not allowed:

- cracks, captivity, delamination, tears and hairs;
- wear of the surface of elements or local dents, leading to a decrease in the cross-sectional area by 10% or more;
- the presence of residual deformations leading to a change in the original size of the element by more than 3%;
- damage to threaded connections and other fasteners. Repair of the rope sling is prohibited.

manufacturer's warranty

The sling was tested with a static load exceeding the carrying capacity by 1.25 times for 3 minutes. The sling is made in accordance with the requirements of PB - 10-382-00, GOST 25573-82 and RD-10-33-93. The guaranteed service life of a sling in accordance with GOST 25573-82 with one-shift operation for 3 (three) months for a sling of the SKP and SKK type and 6 (six) months for other types, and according to RD-10-33-93 - with one-shift operation within 3 months for all types of slings, from the date of commissioning. During this period, the manufacturer undertakes to eliminate the defects caused by his fault free of charge.

Manufacturing, operation, expertise, design, installation and repair of lifting equipment must strictly comply with RD 012-97. Taking into account the stated requirements, steel slings are inspected every ten days or monthly before use. Regular inspection with flaw detectors is recommended. The devices help to determine the degree of wear of the slings, the presence of rust, breakages.

During each inspection, special attention is paid to the following areas: fastening in cable junction points with any structure, places of increased wear, areas for sealing the ends of the product and passing through structural elements.

There are several ways to control:

• indirect. To assess the technical condition of the sling, an integral technique for angular and linear deformations is used;
• visual. The examination is carried out by specialists using special equipment;
• flaw detection. The devices allow ultrasound, X-ray, magnetoscopic examination;
• instrumental. This implies the use of measuring instruments that indicate the degree of wear of the wires, the section of the rope.

What are the criteria for the rejection of steel slings

• The wear of the section of the upper layer of the wire by 40% is observed, the length of the damaged area is not taken into account.
• The section of the steel sling has decreased by 7% or more due to the effect of corrosion on its surface. Also, rejection of steel slings is mandatory, when, as a result of rupture and internal wear, the core is damaged by 10% (if the product belongs to low-rotating ones, then the sling is rejected with an indicator of 3%).
• Wire breakage is noticeable by 40%.
• The cross section has increased by 7%, which is caused by a change in the size of the core under the influence of sharp temperature changes. This phenomenon is extremely dangerous.
• The strength of the wires does not meet the standards of certain lifting equipment. Inspection is carried out using flaw detector.
• Flattening of the rope along its length is noticeable, which is caused by increased wear of the block strand.
• Wave formation is observed, resembling a spiral shape along the longitudinal axis of the sling. This case is also extremely dangerous.
• During a visual examination, creases, twists, deformations, and bends were found.

The above defects make the product less durable and reliable, therefore, steel slings are immediately rejected.

An example of a steel sling rejection

As a result of welding, the molten metal enters the cable, which is also negatively affected by the electric current. The rejection of the steel sling in this case occurs due to the effect of high temperature, which in turn forms burnt areas on the product, soot residues become noticeable, and a color change is observed.

Steel rope slings are not allowed to work (i.e. it is mandatory to reject such rope slings or repair or disposal) made in accordance with GOST 25573-82 and RD-10-33-93 in the following cases:

Lack of a passport for the sling or tags with the specified information about the sling

· If there are knots, kinks, kinks on the cable, or when the cable is twisted.

If the diameter of the cable has decreased due to wear or corrosion by 7% or more

In the case of a decrease in the diameter of the outer wires of the cable due to wear or corrosion by 40% or more, the sling is simply dangerous, the rejection of such a sling is necessary immediately

· If a strand of rope breaks.

When squeezing out the rope core

If the lanyard is damaged by temperature or electric arc discharge

· If the thimble of the sling is deformed, the rejection of the sling must be done without delay. This side is already dangerous.

If the wear of the thimble section exceeds 15%

If there are cracks on the crimping sleeve or its dimensions change by more than 10%

In the absence of safety locks on hooks or other load-gripping elements of the rope sling

If any of these damage occurs, the rope slings are rejected. Further use of such a sling is dangerous.

Do not repair the rope sling yourself.

On structural elements of the rope sling (such as links, hooks, hangers, etc.), the following are not allowed:

3. deformations leading to a change in the dimensions of the sling element by more than 3%.

4. Damage to the fasteners of elements and screw connections.

The service life of rope slings should also be observed.

Rope slings are tested with static load, which exceeds the lifting capacity of the sling by 1.3 times for 3 minutes. Rope slings are manufactured in accordance with GOST 25573-82 and RD-10-33-93.
Correct operation of the rope sling is guaranteed when working in one shift within 3 months for USK1 (SKP) and USK2 (SKK) slings and 6 months for branch slings and VK type slings (the time is counted from the date of putting the rope sling into operation).

Rejection of chain slings - rules and regulations

Rejection of chain slings manufactured in accordance with PB-10-382-00 and TU 3150-001-52466920-2005 is mandatory if:

In the absence and damage of the sling tag, as well as in the absence of a passport for the sling

If the markings on the elements of the sling are illegible

If the difference in the lengths of the branches of the sling during the free sag is more than 15 mm - the rejection of the sling is mandatory

If the chain link, connecting links and hangers are lengthened by more than 5% of their original size

If, due to wear, the cross-sectional diameter of the chain links or connecting links has decreased by more than 8%

In the absence of safety locks on the hooks or load-gripping elements of the chain sling

If any of the listed defects is found, the chain slings are rejected, further use is unsafe.

Self-repair of chain slings is prohibited.

On structural elements of the chain sling (such as shackles, hooks, connecting links, etc.), the following are not permitted:

1.cracks of any size, delamination, tears and hairs

2.Surface wear and dents, which lead to a decrease in the cross-sectional area of ​​the sling elements by 10% or more

3.deformations leading to a change in the dimensions of the sling element by more than 5%

4. Damage to fasteners of elements and threaded connections is a clear sign of the need to reject slings.

Rejection rates for steel ropes used on towers, elevators, winches, funiculars, cranes, cable cars and other lifting structures are set out in Guidance Document 012–97.

1 Rules for the control of steel ropes

RD 012–97, in accordance with which ropes are rejected, is recommended for the manufacture, operation, examination, design, installation and repair of lifting equipment for all individuals, enterprises, foreign companies operating in the Russian Federation, organizations. According to this document, control is carried out:

• periodically: every 10 days;
• every shift: before using the lifting equipment.

Also, special inspections with the use of flaw detectors are provided.

Such inspections are mandatory for technical inspections.

They allow you to control the loss of section, the presence of rust, possible breaks and wear of the outer and inner wires of the product. Note that all these inspections are carried out regardless of the type of lifting structure on which the rope is installed.

During inspections, special attention is paid to the following areas of the rope:

• mounts on the cab, drum, counterweight;
• sections that pass through equalizing, fixed and movable blocks;
• internal parts, where increased structural wear is usually recorded;
• areas for sealing the ends of the product.

• indirect (in other words, deformation): it is understood that the technical condition of the product is assessed using an integral method for angular and linear deformations;
• visual: examination by a specialist who can use special means (in particular, certain optical devices);
• flaw detection: devices (flaw detectors) are used for ultrasonic, X-ray and magnetoscopy;
• instrumental: measuring instruments are used, with the help of which such product indicators are measured as deviations from the straightness indicator, wire wear, rope cross-section.

2 Rejection of steel ropes - all its criteria

The safe use of products is determined taking into account the following criteria:

• internal and surface wear;
• the nature of wire breaks and their total number at a specified length;
• local reduction of the rope cross-section (situations when a core rupture is noted are also taken into account);
• corrosion manifestations (internal and surface);
• active elongation of the residual type after running in the product;
• the presence of zones of concentration of wire breaks;
• breaking strands (one or more);
• resizing the lay;
• the presence of deformations, expressed by the extrusion of strands and wires, waviness, bends, basket-like, creases;
• exit from the outer wire lock;
• the presence of damage caused by an electric arc discharge, exposure to high temperatures;
• reduction of the inner section (transverse diameter of the wires).

A rope is immediately rejected in the following cases:

• With a decrease due to wear of the cross-section of the wires located outside, by an amount of 40%. In this case, the length of the wear area is not taken into account.
• In the case of a decrease in the section of a steel rope caused by corrosion or wear (surface), by 7 or more percent in relation to the nominal diameter (even in cases where the wires do not have visible breaks). If ruptures or internal wear have damaged the core of the product by 10% of its nominal size, the rope is also rejected (for low-spinning products, the rejection should be made at a rate of 3%).
• In the event of a wire break (as such is also understood as a situation when one wire wears out by 40%).
• An increase in the cross-section of the product by 7% (a very dangerous phenomenon, since it is caused by the swelling of the core under the influence of high humidity, and then its freezing when the air temperature drops).
• The loss of strength of the wires is higher than the permissible standards for each individual type of lifting equipment. This loss is determined by a decrease in the cross-section of the wires (check is carried out by a defectoscopic method).
• Flattening the product lengthwise. It is caused, as a rule, by significant wear of the block strand.
• With undulation described by an excessively high spiral shape of the longitudinal axis of the rope. A particular danger is posed by a situation in which the directions of the lay of the steel product and the spiral coincide.
• Extrusion of wires with a number of three or more, fixed on the length of the rope equal to its six diameters. In fact, extrusion is a delamination of the structure that occurs when the wire friction is high.
• Upon detection (visual analysis) of creases, twisting, deformation of a basket-like shape, bends. With all the defects voiced, the product loses its strength, and significantly.

3 Important standards for the rejection of steel ropes of various hoisting mechanisms

The elongation of a steel product by more than 5 percent of its working length is considered to be a rejection criterion. On ropes that are used on friction pulleys, the permanent elongation always increases rather quickly. This causes one of the machine ropes to slip (even when the pulley is fitted with a tensioner).

Guy ropes and bearing products are rejected when the initial length of the section, which is six diameters of the product, increases by 9 percent during operation. Such an indicator signals that there are 100% critical deformations in the rope that can cause torsion of the structure due to wire breaks (internal).

The product is immediately rejected if a thermal effect on it was recorded during the check. Signs of exposure to elevated temperatures are the following:

• the color of the rope has been changed in any part;
• the presence of burntness;
• soot residues.

Most often, these symptoms are caused by the effect of electric current, splashes falling on the structure during welding activities, and the ingress of molten metal onto the rope.

Products mounted on lifting units with a closed design must be immediately replaced, in accordance with the standards for rejection of steel ropes, when:

• a visually fixed defect of the wire lock (external);
• wear by 50 percent or more of the shaped outer wire (the amount of wear is determined by its height);
• 12 cut off shaped outer wires along the entire length of the product, or 3 along a length equal to 30 diameters of the ropes;
• exit of at least one outer wire from the lock.

Low-rotating products, which are usually used in elevator equipment, are rejected in the presence of eight wire breaks with a length of the surveyed section of 30 diameters and four in an area of ​​6 diameters. It is worth noting separately here that when the elevator car is fastened with two steel ropes, rejection is performed for each of them. If necessary, it is allowed to change one rope, which is more worn out.