WEBBING SLING (LIFFTING BELT/DUPLEX STROPS)INDEX-INTRODUCTION-ROUND-WEEBING SLING-COLOUR CODE FOR WEBBING SLINGS-MARKINGS-TAG-SLING TAG-SLING CERTIFICATE-SLINGS MATERIAL-TYPES WEBBING SLINGS-PACKING-PROTECTIVE-CHART-INSPECTION-STORAGE/HOUSKEPPING-SAFE USE OF ROUND/ WEBBING SLING-OPERATING PRACTICES
INTRODUCTIONFLAT and ROUND- WEBBING SLINGLearn the basic of webbing sling, including the nomenclature, how it is constructed, and howdiameter and lay measurements are made.How to choose the right webbing sling for your needs, how to extend sling service life, theimportance inspection, and how to properly store and handle webbing sling.• Colour coded to identify WLL• Can be manufactured using various materials eg. Polyester Nylon Polypropylene Kevlar• Usually polyester (resists acids…damaged by alkalis)• The webbing is produced in various widths .May be single double (simplex, duplex ) or triple thickness. Ultimate strength and flexibility is governed by the number of layers of webbing stitched together.• May have “d” links attached or other end fittings attached• 7:1 safety factor
ROUND- WEBBING SLINGRound slings consist of an unspun hank of polyester protected by a sheath or cover.Due to the construction of a round sling, the load bearing element of the sling iscontained within the core.The length of a round sling is measured at its circumference.Provided that a round sling outer sheath or cover is in good condition -no cuts, tears or friction burnsIt can be reasonably assumed that the inner core is undamaged andthe sling is satisfactory for use.Roundslings are almost always used like this:-WLL reduced by 20% in choke hitch.E.g. 2t WLL for vertical useSWL reduced to 1.6t in this hitch.
COLOUR CODE FOR WEBBING SLINGS Purple1 stripe = 1Te SWL Green2 stripes = 2Te SWL Yellow3 stripes = 3Te SWL Grey4 stripes = 4Te SWL*Number of black stripes indicates SWL.(The colour is depend on the manufacture)
MARKINGS-TAGMarkings or code toShows ;- Name or trademark of manufacturer SAFE WORKING LOAD Rated capacities for the type of hitch Type of material Identification numberLABEL COLOURS CODE Green - Polyamide (Nylon) Alkali Resistant Blue – Polyester Acid Resistant Red/Brown – Polypropylene Resists Acid & Alkalis damaged by solvents.
MARKINGS-TAGROUND SLINGS Stripes show WLL for straight lift Sleeves provide protection on e.g. 3 stripes = 3t sharp edged loads Label gives more detailed information for WLL of sling in different configurations
SLING TAGIdentification number & date tag on webbing sling WRONG MARKING
SLING -CERTIFICATEEmployers should hold the sling Certificate ofConformity and where produced a TestCertificate. - Not just because the law so requires it -but because it may be vital evidence in theevent of a failure of that equipment while inservice.The certificate is documentary evidence of thelegal SWL of the sling.
SLINGS MATERIAL SUBSTANCE ORGANIC SOLVENTS Net rope ACIDS ALKALIS (XYLENE, TOLUENE, TRIC, PETROL, WHITE SPIRIT) OILS material ETC. Susceptible to Susceptible to Natural fibres Very susceptible Very susceptible to attack- becomes attack (Manilla & Sisal) to attack attack embrittled Susceptible to *Highly resistant to *Highly resistant to Nylon *Highly resistant attack attack attack *Virtually Polyester *Highly resistant Susceptible to attack *Virtually unaffected unaffected (Terylene) to attack Susceptible to *Highly resistant *Highly resistant to Polyethylene attack, particularly if *Not affected to attack attack solvent is hot. Attacked by some *Highly resistant *Highly resistant to solvents *Not affected Polypropylene to attack attack e.g. Xylene and Toulene*May be suitable under the above mentioned conditions
TYPES WEBBING SLINGS Choke hitch they must be downrated by 20% when used in choke hitch. Basket hitch the WLL is twice the vertical WLL. Manufacturers supply charts to indicate the considerable variation in WLL which web slings are subject
PACKING-PROTECTIVEFLAT WEB SLINGS• When using web slings extreme care should be taken to prevent damage to the sling due to sharp edges on loads. On supported loads the requirement to use packing is more pronounced than with chain.• Protective sleeves are available from suppliers which will reduce the damage from loads with sharp abrasive edges. E.g. Secutex Packing on sharp edges
INSPECTIONABRASIONLocalised abrasions is the result of movement of the sling over sharp edges,this will significantly reduce the strength of the sling and justify removal fromService.FRICTION BURNSA webbing sling that has been heated will display hard, brittle, shinypatches at the points where the high temperatures occurred and fused thefibres together.Damage usually occurs across the whole width of the sling and can bedetected by folding the sling during inspection. These hard patches are slingweak points and are sufficient evidence to withdraw the slings from service.Friction is the most common cause of heat damage to webbing slings.Ensure that a sling under tension is not allowed to skid along loadsurfaces.Ensure that the sling is not subjected to point loading such as pulling ontoa sharp corner. This produces very high pressure at the point and can resultin heat fusion in the sling material.
INSPECTIONCUTS Cuts in webbing slings usually result from contact with unprotectedsharp edges. Cut damage is similar to that of „friction burns‟ except that the cut maybe clean, or matted and soft in appearance. Inspect for cut damage in the same way as for friction burns. Any cuts in the edge of the webbing will significantly reduce slingstrength and justify removal from service.WEARDamage from wear arises only in local areas of the sling. It is caused by: Dragging along the ground / deck. The „bight‟ being made in the same place for too many lifts. Wear damage from a scuffed surface will appear in patches. If scuffingis severe whole threads may be broken.CHAFFINGThe degree of chaffing will vary. Even minor chaffing will result in someloss of strength. Substantial chaffing, especially when it is localised, will bejustification for removal from service
INSPECTION• Web slings should be examined along Sewing thread abrasion their length for surface chafe, cuts in the webbing, cuts or chafe damage to the selvedges and any damage to the stitching, eyes or end fittings.• The effect of chafe on the surface is variable. Any substantial chafe, particularly localised, should be viewed critically.• Local abrasion, as distinct from general wear may be caused by the sling passing over sharp edges and will result in a serious loss of strength.• Heat damage may show as hard spots and could be generated byfriction, particularly at the bight when choke hitch is used. Abrasive Damage
INSPECTION CUT BROKEN THREAD S Load bearing core Cuts, particularly at the selvedge will result in a serious loss of strength.Outer cover A sling so affected should be taken out of service immediately. CUTS IN THE OUTER COVER
INSPECTIONCHEMICAL ATTACK• Chemical attack is indicated by local weakening or softening of the material in the webbing so that surface fibres can be rubbed off, as a powder in extreme cases.• Chemical attack/contamination may show as discolouration and is a clear indication of damage to the sling.
SAFE USE OF WEBBING SLINGWebbing slings should not be used for general lifts.Use only under strict control whenever delicate, fragile, or specialistlifts are required.So Consider: Will the sling damage the load? Will the load damage the sling? Is it hot? Are there chemicals about? Do you need adjustment? How will the sling be Attached? What does the load weigh?
SAFE USE OF ROUND/WEBBING SLINGSUMMARY – DO’S• Stand back & “size up” the task• Check lifting points are strong enough for the job.• Obtain the weight of the load and check the SWL of the accessories.• Select the correct accessory i.e. length, construction, strength & suitability.• Check the C/G of the load• Inspect the condition of the accessories- before use- check for: chafe/cuts/seam damage• Observe the mode factor, ensure that the sling is of adequate strength-certificate• Check the loads are slung correctly.• Stand clear of the load• Take the strain before lifting the load.• Check accessory and lifting point attachments on suspended loads.• Give clear & unambiguous signals/instructions to the crane operator.• Stand where you can be seen by the crane operator when giving signals.• Use a tag line to control long/awkward loads being lifted• Avoid shock loading.• Protect a webbing sling when passing it round a surface might cause damage to the fabric.• On supported loads use packing where sharp edges are present.• Ensure that lifting hooks or devices have smooth edges that will not damage the eyes of the slings• If slings are to be used in chemically abnormal atmospheres or in constant high temperatures then seek confirmation of advice before used (A nylon (polyamide) sling can lose up to 15% of its SWL when wet.)
SAFE USE OF ROUND/WEBBING SLINGSUMMARY DON’TS• Drag accessories along the ground – carry them or use mechanical aids.• Drag accessories from underneath a load it could pull the load over and damage the gear – use bearers• Pull the sling from under the load if the load is resting on the sling.• Use unauthorised lifting accessories, always ensure they have test certificates and as appropriate, a 6 monthly, the SWL is not known - marked• Guess the weight of the load.• Shorten any accessory by twisting or knotting.• Ride on the load or in the accessories.• Walk/work underneath any load.• Leave accessories lying around on the ground – pick them up.• Leave damaged or condemned accessories where they could be used by others.• Place hands or feet near the bight of any accessory.• Use a sling with a load without unprotected sharp edges• Permit the opening of the soft eye in excess of 120 degrees• Use a sling with a damage eye, has damage outer sheath (round), any damage• Allow the eye of a webbing sung to be opened by more than 20º• Use choked lift without protecting sling eye (allow angle of choke to form naturally)• Lift when the sling is twisted
OPERATING PRACTICES• Keep the included angle as small as possible.• Keep the eye opening angle within 200 by using shackles – if not the eye of the sling could be burst open. Large included angle Sharp edged load Sling will be cut here
OPERATING PRACTICES Just what I need to get the engine out of my old motor !
OPERATING PRACTICESQuestion:What is wrong with this picture?
OPERATING PRACTICESAnswer:Always use a shackle – do not attach the sling to the main hook • When using web slings care should be exercised when connecting the upper ends to a crane hook – the eye opening angle should not exceed 200 • Shackles should be used to connect the upper legs to prevent destruction of the sling(s). • If web slings have to be joined together then shackles should be used – they must never be joined together by tying knots in them.
OPERATING PRACTICESQuestion:What is wrong with this picture? RESUL T
OPERATING PRACTICESAnswer:Sharp edges should always be packed to prevent damage