Test Procedure For Complete Twin-Path® Sling Products
In the proof testing, the pins should be 26 mm (1 inch) diameter or larger.
The slings should be pulled to twice their working load limit. Slings will be held at the proof test limit for a minimum of 15 seconds and then the tension may be released.
Testing machine is required to test Twin-Path® sling products and load yarn to check if they meets or exceeds the standards as described in ASME E-4.
The break testing of the sling should be conducted and recorded according to the aforementioned rules. All the diameter of pin should equal to the half of nominal sling width or even larger.
Proof testing is mandatory for each newly manufactured and repaired Twin-Path® sling.
After the sling is proof tested, the tell-tails should then be trimmed to length prior to shipment.
Repaired slings or fittings should be proof tested before they are returned to service.
These recommended standard specifications are the guide to users, industry and govern
Tell-Tails should be attached to the each sling. If tell-tails are invisible, the sling should be removed from service; if the sling shows any chemical degradation, the sling should be also removed from service and sent to manufacturer for evaluation and repair.
This is important for personnel to inspect any cutting or tearing on the outer cover of sling. Damage on the cover may indicate core yarn would be damaged as well. Hence slings with cuts should be removed from service, sent to the manufacturer for evaluation and repair.
Slings should be inspected by any heat damaged. Aramid Sparkeater slings should not be exposed to temperatures over 149℃/ 300°F; K-Spec® and polyester core slings should not be exposed to temperatures above 82℃/180°F. Low temperature to minus 40℃/ minus 40°F do not affect the strength of slings. The effect of other temperatures on slings can be referred to the manufacturer.
Slings using with aluminum fittings should not be used where fumes, vapors, sprays, or mists of alkalis or acids are present.
Twin-Path® slings and any fittings attached should be inspected regularly. The initial inspection should be done and recorded by a competent person. Besides, the slings should be visually inspected before each use.
Inspection reports should be recorded and kept on files in the safety department of the plant or site where used. Inspections may be done more frequently based on the frequency of use, severity of conditions, experience of past service life.
Slings should be examined throughout their length for any abrasion, cuts, heat damage, fitting distortion or damage, illegible tag, and if any doubts are held by the inspector, the sling should be removed from service. Core integrity is determined by Fiber optic light transfer. If deterioration is found, the sling must be removed from service and returned to the manufacturer for evaluation.
Slings removed from service that are not repairable should be rendered and destroyed completely unfit for future use.
Abrasion, heat damage or cuts on the cover may indicate a loss of strength to the load core and these slings should not be used until evaluated by the manufacturer. At the area of damage, cover should be opened and the number of core yarns should be visually inspected and counted.
1:Bulk strength is defined as strength per circumference squared. 2:Working is defined as rope actually in use under a cycling load. 3:Co-efficient of friction is based on reluctance to slip or slide. 4:Critical temperature is defined as the point at which degradation is caused by temperature alone. 5:Cold-Flow (Creep) is defined as Fiber deformation (elongation) due to molecular slippage under a constant steady static loading situation. Fibers that have these inherent characteristics will display extremely low or negligible creep if minor fluctuation occurs in the rate and/or frequency of load levels. In rope form, this would apply to polypropylene, polyethylene and HDPE olefin Fibers.
When not in use, synthetic slings should be stored in a clean and dry place rather than high temperature and unventilated places.
在充滿化學制品環境下會影響合成纖維吊帶的強度。不同的化學制品會與Covermax® 尼龍、聚酯、人造纖維和烯烴產生不同的化學 反應。
Chemically active environments can affect the strength of synthetic slings. Different chemicals will react with different exposure to Covermax® bulked nylon, polyester, aramids and olefins.
Aramids are resistant to most ketones, alcohols, dry cleaning solvents and other organic solvents. Their acid resistance are superior to that of nylon but are not as good as that of polyester. Aramids show good resistance to alkalis at room temperature, but are degraded by strong alkalis at high temperatures.
Aramids are compatible with fluoride-containing elastomers, resins, and refrigerants at high temperatures, and are resistant to fluorine compounds in concentrations usually encountered in stack gases from metallurgical and rock-processing operations.
The resistance of aramids to sulphur oxides at temperatures above the acid dew point is superior to that of polyester. Below the dew point, concentrated sulphuric acid may condense on the Fiber and cause a progressive loss in strength.
In moderate to strong acid or alkali environments, evaluation of aramids should be made to ensure that the yarn will perform acceptably before use.
Polyester and nylon are not significantly affected by most compounds of the following classes: Alcohols, dry cleaning solvents, halogenated hydrocarbons, ketones, soaps and synthetic detergents, and water (including sea water)
Polyester also shows good to excellent resistance to:
─ Aqueous solutions of most weak acids at the boil, and to most strong acids at room temperature, but is disintegrated by concentrated (95%) sulphuric acid at room temperature;
─ Aqueous solutions of strong alkalis at room temperature, but is degraded at the boil;
─ Oxidizing agents, and is not degraded by bleaching treatments ordinarily used for textiles.
Nylon is not significantly affected by most aldehydes, alkalis, ethers, or hydrocarbons, but is deteriorated by dilute acids (e.g. hydrochloric acid and sulphuric acid in 10% concentrations at room temperature cause a noticeable loss in breaking strength in 10 hours).
Solvents for nylon includes:
Concentrated formic acid, phenolic compounds at room temperature, calcium chloride in methanol at room temperature.
Hot solutions of zinc chloride in methanol Benzyl alcohol at the boil.
Aramids are resistant to most weak acids and alkalis, ketones, alcohols, hydrocarbons, oils and dry cleaning solvents. Strong acids and bases and sodium hypo-chlorite bleach attack aramids, particularly at high temperatures of high concentrations.
K-Spec® core yarn strength retention is based on test results of components at 65℃/150°F (or less) for 6 months. K-Spec® has a 100% strength retention when exposed to age, 10% detergent solution, rot and mildew, sunlight and toluene; 99% strength retention when exposed to acetic acid, gasoline, hydrochloric acid 1m, hydraulic fluid, kerosene and sea water; 98% retention when exposed to 25% ammonium hydroxide, 10% hypophosphite solution, and 40% phosphoric acid; 97% retention when exposed to 5m sodium hydroxide; 95% retention when exposed to Portland cement and sulfuric acid; and 88% retention when exposed to Clorox®, and nitric acid.
The weight of the load should be limited within the WLL of the sling.
The type of load, hitch and environment factors should be considered when selecting a suitable sling.
Slings should not be loaded in excess of the WLL. Be aware that angle of lift, diameter of pins and edges may affect the WLL of the lifting sling.
Choker hitches are the least effective way to use a sling based on the WLL. Slings used in a choker should not be forced to tighten around the load by pounding with hammers or other objects. To maintain balance of the load, two chokers are suggested to be used. Using one choker in the center of the load may create an unbalanced situation which could lead to an accident.
Slings used in a basket hitch should keep balance on the load for preventing slippage and accidents.
Slings should be compatible with the accessories used. Also, the weight of load should be lower than the WLL of slings and accessories. Proper shape and size of accessories should be used to assure the sling would seat properly.
Slings should be protected from cutting and edges. All protrusions and abrasive surfaces should not chafe with the sling. If friction is unavoidable, CornerMaxTM Pad is recommended to be placed between the sling and the load. The pin area of a shackle can cause synthetic slings to cut, so placing synthetic slings on the pin should be avoided unless it is protected.
Slings should not be dragged on the floor or drawn across other surfaces which may damage the sling.
Never twist or tie the sling in knots to shorten.
Never pull the sling from under loads resting on the sling.
Never drop objects on sling or run over them with vehicles.
Never use the damaged slings.
Make sure each sling hitches can control the balance of the load.
When lifting, personnel should be kept away between the sling and the load, and between the sling and any lifting accessories like hooks.
Personnel should stand clear of suspended loads.
Personnel should not ride on the sling or suspended loads.
Never snatch or shock loading.
Never twist and kink the legs of the sling.
Load applied to the hook should be centered in the bowl of the hooks rather than the mouth of hooks.
Personnel should be alert for possible snagging during lifting with or without the load.
The slings should hold or support the load from the sides above the center of gravity, so that the load will not tilt when lifting the load.
Proper length of slings can ensure that the angle of the slings to the load does not reduce the WLL of the sling for a given angle.
Only use legibly marked or labeled slings. If the tag is not legible, or missing, the sling must not be used.
Keep labels or tags away from the load, the hook and the angle of choke.
Inspection of synthetic slings must be done before each use.