When it comes to lifting tackle, there are essentially four key factors that affect safety, namely the suitability of the equipment, its quality, its condition, and the way it is used.
Suitability: When we talk about suitability, many people think in terms of the basics. Is the sling long enough and strong enough. While it is true that a good slinger can lift almost anything with a range of general-purpose equipment, it is certainly not always the most efficient or safe method. Moreover for a repetitive series of lifts, it often takes longer to position the sling and get it just right every time.
I therefore urge those planning lifting operations to widen their thinking beyond the everyday equipment. Even within the readily available range of off-the-shelf equipment there is a wide variety of special-purpose equipment, but for some jobs the planner should be thinking of bespoke equipment.
This does mean planning further ahead. It is true that major lifts are usually planned in considerable detail well in advance. Even for the more routine lifts someone usually thinks early on about the capacity and reach of the crane required, but as for how the load and crane are connected it is often left to the people on the ground on the day of the lift. It is still one of the most common complaints I hear in the industry that the lifting tackle is left to the last.
Even when general purpose equipment is suitable there is often only a poor selection available. Last minute lash ups made under pressure of time and money are a common cause of accidents.
Often the problem arises because the designer of the load hasn’t thought about how to lift it. The provision of a lifting point, often at very little cost, would have eliminated most of the risk.
It is not always possible to provide lifting points, but we still see loads such as pipes being lifted with standard sling hooks jammed over the pipe end with the load on the tip of the hook and yet pipe hooks are readily available, designed for the job.
We see bundles of materials such as reinforcing bar being lifted in simple choke hitch which the slinger tightens by battering it down with a piece of wood or scaffold pole causing local overload. With a long enough sling leg, a full wrap and choke hitch would hold the bundle much more securely without overload.
We see loads lifted into positions where access to release the slings is difficult or where there is a risk of the slings being trapped. Then we see operatives resort to crude and potentially dangerous methods to release the slings and get them out.
However, it is when lifting loads without lifting points and which can’t be hooked into or wrapped by the sling that the more specialised equipment comes into its own.
I’ve mentioned the major lifts, but increasingly employers have to consider and control the risks arising from manual handling and there is a wide range of equipment now available to mechanise the relatively minor jobs previously done manually. Much of this specialist equipment is available for hire so capital cost should not be a problem.
The message is:
• plan ahead.
• specify lifting points on the load if possible.
• consider how to:
– connect, set down and release the load.
– think more widely about the equipment.
Quality of equipment: By this, I mean the fundamental quality as designed and manufactured rather than the state of repair, which I shall come to next. There has probably never been such a diversity of quality on the market as there is today, and regrettably the buyer’s specification for lifting tackle is all too often minimal and the key deciding factor in the purchase or hire of equipment is the price.
So the trade gets asked for a two-leg chain sling SWL 7.5t, 2m long, or a hand chain block SWL 1t, 3m height of lift. There is no reference to a standard or any other technical requirements. Needless to say, you get what you pay for.
But if you are operating, for example, outdoors in winter in northern Europe, the equipment is likely to experience temperatures at which some materials have little resistance to shock load.
A good example is the failure of a spreader and fork arrangement. It was used for lifting prefabricated concrete sections and failed catastrophically when a coupling component parted. The pin had been wrongly heat treated and was more brittle than it should have been.
As well as low temperatures there are a host of other environmental and local conditions including sunshine, heat, chemicals and pollutants which can adversely affect the materials.
Finally there is the question of durability. Equipment such as a hand chain block used to be made for regular and prolonged use. Adequately maintained they would literally last a lifetime but they were expensive and heavy. Today, they are used as portable tools and weight matters but the quality of some is such that they need very frequent inspection to ensure safety.
Even when equipment purports to be to a standard, it is not always what it seems. The quality of the standards themselves sometimes leaves a lot to be desired. In Britain we traditionally had fully detailed standards with full dimensions and tolerances and full material specifications but some manufacturers and suppliers, particularly those importing from far east sources, started to make claims such as ‘generally in compliance with’ the standard which over time often came to mean that all they complied with were the nominal dimensions.
Again, within the ISO standards there is often considerable scope for variation of quality. Many older ones are rather loose performance based standards which, to be accepted worldwide, were often the lowest common denominator rather that the best technology of the day.
In Europe today we have among the best quality standards with clear and verifiable requirements, which are being widely adopted in many parts of the world. But, and it is a big but, there are still manufacturers who from carelessness or other motives claim their product complies when it does not. We had a recent case of this in the UK with webbing slings supposedly to the European standard but failing in one case at half the required load.
The message is:
• specify fully
• put requirements first – price second (quality is remembered long after price is forgotten)
• ensure what you get is what you specified
• beware of very low prices
Condition of the equipment: Below hook equipment can have a hard life that can be shortened by misuse. There are a lot of things that can cause a crane to fail, particularly a mobile or tower crane where ground conditions and weather can be very significant but, once safely erected and commissioned, unless a crane is overloaded or deliberately abused, it operates in a relatively controlled environment and there are relatively few things that can go wrong on a day to day basis. This is particularly true of an overhead crane or hoist in a factory.
However, by comparison to the crane, a sling or other lifting accessory is more vulnerable to damage. Remember also that the sudden release of the load if the lifting tackle fails can have a catastrophic effect on a counterbalanced crane.
Frequent in-service inspection is vital. A well trained slinger should know what to look for and be able to quickly cast their eye over the equipment every time it is used. In the case of the coupling failure I highlighted earlier, there was also clear evidence that the pin had been fractured for some time before the coupling failed. Had it been regularly inspected this would have been found in time to prevent the failure.
Here I want to make an important point about the culture of the user organisation. No one likes to be blamed for making a mistake so it is vital that, when it comes to accidentally damaged lifting equipment, there is a no blame culture. This is not to encourage carelessness, but to ensure that damaged equipment is not kept in use or left available for others.
It also means having some spare equipment available, particularly that which is most vulnerable. It’s not that expensive in the broader context of other costs.
As well as accidental damage, most equipment requires some form of maintenance to keep it working safely. Even a simple sling might need cleaning and drying. Mechanisms such as those in a clamp or a chain block need to be free of corrosion to operate satisfactorily but it is necessary to ensure that the methods used are not in themselves the source of further problems.
Most countries require a formal inspection of lifting equipment at regular intervals usually also requiring a record to be kept. In the UK we have had such a system for many years and to emphasise the nature of the inspection and to differentiate it from that normally done by the day to day user, we call it a thorough examination. The maximum period between thorough examinations of lifting tackle is normally six months. The thorough examination is intended as a long stop measure. Indeed, if when examined the equipment is found to be dangerous, it means that the in-service inspection and maintenance regime has failed and, in the UK, it is reportable to the enforcing authorities.
This approach of frequent in-service inspection coupled with a maintenance programme and backed up by a regular in-depth inspection is good practice whatever the local regulations.
Lastly, ensuring that the equipment is fit to use includes storing it in a manner that prevents deterioration and accidental damage and usually it also means preventing unauthorised use, an all too frequent cause of damage as well as loss.
A control and issue procedure is desirable. If the size of the operation justifies it, a controlled stores is ideal but if not then at least a lockable container with access restricted to identifiable persons. Someone should be responsible for ensuring that the equipment has been inspected and maintained and is fit for service. In the offshore industry containerised rigging stores are a common solution which can be equally valid on a construction site or even in a factory.
Within the storage, equipment which is not fit for service should be separated and securely quarantined to prevent accidental use.
The message is:
• check before each use and after any incident
• encourage a no blame culture
• have a regular inspection and maintenance regime
• have spare equipment at least for the most vulnerable items
• have a formal ‘long stop1 inspection at least every six months
Use of equipment: I’ve already made the point that the way in which lifting tackle is used can result in failure even if the equipment is suitable for the purpose and the load being lifted is within the safe working load. This talk is not about how to use the equipment but it is worth highlighting the main causes of failure. Essentially there are three:
• Errors in the geometry of the arrangement.
• Equipment damaged by sharp edges.
• Excessively high dynamic loads, ie shock loading.
It is essential that the slinger has an adequate knowledge of these causes and knows how to avoid them or compensate for them.
Each factor affecting safety that I have outlined above needs to be the responsibility of people who are sufficiently knowledgeable and skilled to carry them out properly. The planner, the specifier, the buyer, the inspector, the maintainer, and the slinger all need appropriate training, but consider also the attributes required of the person. In particular the physical abilities necessary such as eyesight, balance and most important their attitude. Training can enhance knowledge and skills but cannot change the fundamentals. It is also important to verify that the training has been effective.
