My involvement in the design and manufacture of synthetic sling products began in the early 1970s. At that time the ‘web’ sling was fairly new and not widely used. During ensuing years, synthetic slings took on wide popularity of use for two, primary reasons: synthetic slings are user and load friendly. The sling user enjoys the numerous ergonomic benefits of the synthetic lifting product, while the load, no matter how delicate, is protected from damage.
The synthetic sling is truly ‘the sacrificial lamb’; it actually commits ‘sling suicide’, and allows itself to be consumed to facilitate its numerous, inherent advantages. It is crucial for the informed synthetic sling user to realise the direct correlation between the consumable nature of the sling and the need for replacement, prior to catastrophic sling failure.
Our discussion of sling inspection will focus on three distinct topics: sling inspection systems, inspection techniques and removal from service criteria.
Sling inspection systems
A specific procedure for the inspection of synthetic slings is your best safeguard. Consider employing a three-stage system of inspection. Each stage must be given equal attention for the system to be viable. Slings that are removed from service that are not capable of repair should be destroyed and rendered unfit for any future use.
* Initial stage: This level of inspection is done at the time that the product is received into your facility. The inspector should ensure that no damage has occurred during transit, and also verify that the sling work load limits match those contained in the manufacturer’s catalogue. If your facility documents the sling inspection process through written inspection records, the paper trail should begin at this stage.
* Frequent stage: The frequent level of inspection should be done by the sling user before each and every use. The entire sling should be thoroughly examined and removed from service if damage is detected. The sling user should also determine that the sling is proper for the hitch, load and environment.
* Periodic stage: Designated persons should conduct the periodic level of inspection at regular intervals. The interval should be based upon the frequency of use, severity of the service cycle and information derived through the inspection process. Recommendations to prevent damage and enhance service life would be made by effective and informed, periodic sling inspectors. If written inspection records are maintained, they should always reference the unique sling identification number, and be updated to record the condition of the sling.
Sling inspection technique
The sling inspection procedure should be thorough, systematic and non-compromising. Whether the inspection process involves several hundred or several slings, each, individual sling must be inspected over the entire length by way of a thorough visual and a ‘hand over hand’ inspection.
Certain forms of damage are far more discernable through ‘touch’ inspection, than by visual inspection. Heat damaged or crushed web slings, as well as, round or Twin-path slings with melting or damaged yarn can be identified through tactile inspection. Visual inspection alone may not reveal these forms of sling damage.
Once the first sign of damage has been identified, the sling inspector need not go any further. Sling inspection is not a game of baseball, where the rule is three strikes and you’re out. With suspect slings, it’s one strike and the sling is out of service.
Sling inspectors should never play the deadly game of downgrading the work load limit of the sling after damage has been detected. This is sometimes done to get more service life out of a damaged sling. The prevailing rule should be ‘go’ or ‘no go’. The sling can be likened to the space shuttle, ready and poised on the launch pad. It will either launch or not launch. There is no middle ground – the sling is either good or bad.
We recommend the practice of documenting sling inspections through written inspection records, even though legislation or statute generally does not require this. The documentation should include information such as: the name of manufacturer, the sling stock number, width and length, the unique sling identification number (critically important in differentiating similar slings), as well as the condition of the sling. Other important information might also include the date of manufacture and any special attachments, such as, hardware or wear protection devices.
Sling inspection may not be the most dynamic and exciting job, but it is the backbone of a viable accident prevention programme. Two inspectors, working together, can inspect more slings than the same two inspectors working independently can. The inspectors reverse their roles and take turns as inspectors or record keepers.
One of the most beneficial outcomes of a thorough inspection would be the realisation of repetitive forms of damage and the analysis that would lead to specific recommendations. These suggestions may improve the life of replacement slings and the overall safety of the sling users. Such suggestions may include the utilisation of wear protection or an entirely different sling or method of rigging.
The effective sling inspector will make recommendations and pay close attention in monitoring the results to determine an improvement. The evaluation process also allows for further ‘fine tuning’ of the rigging system.
Removal from service criteria
One of the primary reasons for premature sling retirement is the lack of permanent information on the sling identification tag. There are many different materials and just as many methods of encoding the information.
Irrespective of the material or method, the issue of permanency is of key significance. Depending upon the applicable standards, basic information, such as the material used in the construction of the sling and the work load limits for the respective hitches must be clearly legible.
The second most prevalent reason for removal from service would be tears or cuts. The effective sling inspector will not simply replace the damaged sling, but recommend the employment of wear protection to prevent further damage of the replacement sling.
Web slings shall be removed immediately from service if any of the following conditions exist:
* acid or caustic burns
* melting or charring of any part of the sling
* snags, punctures, tears or cuts
* broken or worn stitches
* distortion of fittings
* missing, illegible or incomplete tag
* knots in any part of the sling
* ‘excessive’ abrasion
* other visible damage that causes doubt as to the strength of the sling.
Round and Twin-Path shall be removed from service if any of the above mentioned conditions are present, and if any of the following conditions are visible:
* snags, punctures, tears or cuts which expose load carrying yarn
* broken, cut or damaged load carrying yarns
* broken or worn stitches in the sling cover which causes the load carrying fibres to become exposed.
The removal from service criteria is straightforward. The process can be made overly complicated by uneducated and uninformed sling inspectors and users. When this happens, unfortunately, it is the process, rather than the perpetrators, that generally takes the blame. Remember that the sling is either good or bad – there is no middle ground. If involved parties have any doubts, remove the suspect sling from service and forward it to any reputable manufacturer for a second opinion.
Sling inspection is done for all the obvious reasons, namely for the protection of the sling user, the involved property and the overall job site safety. A viable sling inspection system also has numerous spin-off benefits. Systematic sling inspection will assist in the identification of damage trends, leading to cost effective suggestions and results.
The inspection process can also help to streamline duplicity in certain sling types, designs and lengths. The many benefits of the ongoing, consistent and non-compromising sling inspection system will be enjoyed not only at the job site, but also in the boardroom. All parties benefit, resulting in a win-win situation.
