Crane slings refer to the slings and rigging used to lift heavy objects, including wire ropes, rings, hooks , chains, slings, shackles, etc. For the sake of safety, the standards for the safe use, inspection and scrapping of slings have been formulated, which quoted the "General Rules for the Acceptance of Short Link Chains for Lifting", "Synthetic Fiber Slings for Lifting Slings", and "Technical Conditions for the Use of Lifting Rings for Port Loading and Unloading" , "Forging Shackles for General Lifting" and other documents.
Slings without identification and inspection certificates or reports are strictly prohibited from being put into use.
Daily inspection should be carried out before use, and it is strictly forbidden to put it into use when the damage of the steel wire rope or metal accessories exceeds the scrap standard.
The sling is strictly prohibited from being overloaded.
The angle of the sling under the hook head shall not be greater than 120o.
The slings of special equipment chains, hooks, rings and other metal accessories should be connected with each other by shackles, and their rated loads should be equal.
The sling should be hoisted smoothly, and the impact load should be avoided.
Take effective measures to prevent the wire rope from bending at acute angles or colliding with the load.
It is forbidden to drag or drop the wire rope sling from a high altitude.
It should not be used outside the temperature range of over -40 degrees and 100 degrees.
Do not use it exposed to corrosive gas, liquid or steam.
Wire ropes that are re-used after being out of service for more than half a year (including half a year) should be inspected before use, and can be used only after the inspection is qualified; for wire rope slings with a storage period of more than two years, a tensile test must be sampled in accordance with national standards. Put into use.
Broken wire situation-the number of broken wires and the distribution and degree of broken wires;
Degree of wear-measure the diameter of the wire rope at each wear part;
Corrosion status-whether it is rusty, corrosion status;
Lubrication status——whether the grease is properly present and whether there are debris attached to the grease; keep the surface clean and lubricate with wire rope lubricant once a year;
Deformation and other abnormal phenomena-the degree and location of kinking marks, flattening, damage, loose strands or loose twists;
The tightness of the heavy-duty ring connection part-whether the steel wire rope is dislocated or the alloy indenter is deformed, worn, corroded or cracked.
The number of broken wires at the connection part of the heavy-duty loop is 5% of the total number of wires;
The number of broken wires in a twist length is 13% of the total number of wires;
The diameter of the wire rope is reduced by more than 10% relative to the nominal diameter;
When the wave-breaking deformation occurs, when the length of the wire rope does not exceed 25d
Within the range, d1≥ 4d/3; where:
d—— Nominal diameter of steel wire rope;
d1——The diameter of the envelope surface of the wire rope after deformation;
The wire rope is squashed;
Kink, bend;
The wire rope is severely corroded;
The wire rope is loose or misaligned at the connection part of the heavy-duty loop;
Suppression of joint damage, deformation, cracks and severe corrosion;
The diameter of the compression joint is reduced to 95% of the diameter listed in Table 1 of GB6946;
The scrap standards for metal accessories of wire rope slings shall be implemented in accordance with the relevant provisions of the national standards.
The wire rope slings that are frequently fatigued for hoisting operations should be scrapped after two years of use.
The sling is not allowed to be dragged when it is working to prevent damage to the sling;
The sling is not allowed to be used in knots, and it is not allowed to twist the cargo to make the sling twist when carrying;
Do not use a sling without a sheath to sling goods with sharp corners and edges to prevent damage to the sling;
Hanging cargo for a long time is not allowed;
Do not store the sling near open flames or other heat sources, and keep it away from light;
The sling should be cleaned regularly.
Whether there are perforations, cuts, or tears;
Whether the seams are frayed or the seams are frayed;
Whether there is softening, aging, reduced elasticity, and weakened strength;
Whether the fiber surface is rough and easy to peel off;
No knots in the sling;
Whether there is spot-like looseness, corrosion, acid-base burn, and thermal melting or scorching on the surface of the strap;
Whether the cordon with the red cordon strap is exposed.
Perforation, cut, tear;
The load-bearing seams are frayed and the sutures are frayed;
The sling fiber softens, ages, becomes less elastic, and weakens;
The fiber surface is rough and easy to peel off;
There is a knot in the sling;
There are too many spots on the surface of the strap, such as looseness, corrosion, acid and alkali burn, and thermal melting or scorching;
The cordon with the red cordon strap is exposed.
Frequent fatigue use without damage for 1 year and need to be scrapped.
The actual measured size of the transferred length exceeds more than 6% of the original length;
When used as a sling, the nominal quality grade of the sling is consistent with the grade of the chain used;
Before the chain sling is used, a static load test should be carried out with twice the ultimate working load of a single limb. During the test, it should be suspended for 10 minutes without damage or with no obvious elongation of individual chain links. After passing the test, it can be put into use.
Whether the chain link is plastically deformed;
There shall be no cracks, cracks, obvious corrosion and other defects harmful to use on any part of the sling;
The chain, intermediate ring and connecting ring should rotate flexibly;
The contact parts between the chain links and the connection between the chain links and the end fittings are worn; other parts are worn;
The inspection must be carried out by professional and technical personnel.
The chain link undergoes plastic deformation and stretches to 5% of its original length;
The wear of the contact parts between the links and between the links and the end fittings is reduced to 60% of the original nominal diameter; the wear of other parts is reduced to 90% of the original nominal diameter;
Deep dents in cracks or high tensile stress areas, sharp transverse dents;
After the chain link is repaired, it fails to make a smooth transition or the diameter reduction is greater than 10% of the original nominal diameter;
The fouling cannot be eliminated after distortion and severe corrosion;
The reduction of the dangerous section wear of the end fittings reaches 10% of the original size;
For end fittings with opening degree, the opening degree is increased by 10% compared to the original size;
Exceeding standard defects were found during appearance inspection, size measurement, tensile test, and NDT inspection.
The main ring used to form chain slings, steel wire rope slings, and fiber rope slings should adopt long-shaped rings, and circular rings can be used in other occasions.
The connecting ring must be a long ring.
For the reuse of the rings with scars or significant corrosion, the static tensile test must be carried out in accordance with the requirements of 8.2.6.3.
It is not allowed to re-use defective lifting rings after welding.
The lifting rings on the combined parts of the lifting rigging shall be inspected regularly according to the requirements of the combined parts.
The diameter of the connecting ring connected to the chain must be larger than the diameter of the chain.
The number of chains and cables directly connected to a single ring shall not be more than that of the three limbs. The connection between the limb chains, cables and the main ring shall adopt the E type in Table 1.
Do not use hammering to correct twisted rings.
Throwing rings is prohibited.
Do not pull the lifting ring from under the heavy object or let the heavy object roll on the lifting ring.
It is not allowed to use shackles instead of connecting rings.
The surface condition of the rings;
Wear of rings;
The torsion and deformation of the rings.
The hook used for lifting large rigging of more than 5 tons shall be inspected and non-destructively tested every year
Calculated from the unbent plane of the ring, the distortion rate exceeds 10% of the inner length L of the elongated ring (the inner diameter of the circular ring D) and the deformation rate is more than 5%;
The diameter of the hoisting ring is worn or rusted exceeding 10% of the nominal size;
Cracks, cracks or grooves appear on the rings.
The quality of the goods to be lifted shall not exceed the rated lifting capacity of the hook.
When lifting, it should be stable to avoid shock load.
The load should be placed in the middle of the hook seat.
After loading the corrosive product, the corrosive product remaining on the hook should be cleaned off, and then wiped dry and oiled.
The surface condition of the hook;
Increased opening degree of hook;
The torsion and deformation of the hook;
Wear condition of hook seat;
Hook neck or dangerous section;
Hook with attachment, working condition of attachment.
The hook used for lifting large rigging of more than 5 tons shall be inspected and non-destructively tested every year
The opening degree of the hook exceeds 15% of the nominal size;
The torsional deformation of the hook exceeds 10%;
The dangerous section wears up to 10% of the original size.
Plastic deformation of the neck or dangerous section of the hook;
Unrepairable cracks and cracks appear on the surface of the hook;
When the plate hook bushing wears up to 50% of the original size, the bushing should be scrapped;
When the plate hook mandrel wears up to 5% of the original size, the mandrel should be scrapped.
Overload use is strictly prohibited.
Attention should be paid to the direction of force acting on the shackle, and the horizontal and vertical force is not allowed.
After installing the horizontal pin shaft and screwing the foot, you should turn half the thread pitch, and it is not allowed to tap the threaded part.
It is strictly forbidden to replace the shackle matching bolts with bolts of other materials.
Dimensions: The inspectors measure the dimensions of various parts of the shackle and make a record;
Appearance: In appearance inspection, use a magnifying glass with a magnification of 5 times to observe the surface of the shackle, check for cracks, deformation, and wear, and make a record;
Deformation: Determine whether there is any deformation of the shackle through measurement and close-up inspection, and make a record;
Wear: Determine the wear of each part of the shackle by measurement, especially the top of the shackle, and make a record;
Dangerous section: check the wear and deformation of the section of the stressed component, and make a record;
Flaw detection: Conduct magnetic particle detection on the dangerous sections of the main stressed components and make records.
Shackles used for lifting large rigging of more than 5 tons shall be inspected and non-destructively inspected every year
Buckle body length: the measured size of the shackle length exceeds 0.25% of the nominal size or 0.5mm, whichever is greater;
Deformation: the torsional deformation of the shackle exceeds 10%;
Corrosion: The wear of the shackle parts exceeds 5% of the nominal size;
Dangerous section: plastic deformation of the dangerous section;
Surface: Unrepairable cracks and cracks appear on the surface of the shackle;
Flaw detection: magnetic particle detection of the dangerous section of the main stressed parts found that there are internal defects;
Marking: No load rating is indicated.
Cracks appear;
The wear and corrosion of the cross-section of the stressed component reaches 10% of the original size;
The opening of the forceps body is increased by 10% compared to the original size.
There are more than two broken teeth in the jaws, which cannot be repaired or replaced.
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