Heavy loads on the hook

SAFETY REGULATIONS FOR HANDLING CRANES

Of all the vehicles and technical systems for moving loads horizontally and vertically, cranes represent the pinnacle of performance in many constellations. This applies both to the masses of the goods to be moved and – depending on the design – to the spatial mobility in terms of lifting height and reach.

In view of this, cranes are completely indispensable tools for daily operations and special challenges in many companies. However, their high performance in combination with their expansive dimensions and corresponding weight also make these devices an extremely important safety factor.

To ensure safe operation with these systems and their heavy loads, several provisions have been designed. The most important are

• the German Social Accident Insurance (DGUV) regulation 52/53 “Cranes”,
• the Ordinance on Industrial Safety and Health (BetrSichV),
• the Ninth Ordinance to the Equipment and Product Safety Act (9th ProdSV),
• DGUV regulation 54/55 “Winches, lifting and pulling equipment”,
• DGUV principles 309-001 “Inspection of cranes”, 309-003 “Selection, instruction and proof of competence of crane operators”, 309-009 “Crane inspection logbook”,
• DGUV Rule 109-017 “Operation of load handling attachments and slings in hoisting operations” and
• DGUV Rule 209-012 “Crane operators”.

Reference is also made to DGUV Information 209-091 “Operating cranes – In-plant transportation with cranes in steelworks, rolling mills and foundries”.

Ultimately, these specifications should always ensure one thing: Heavy loads should be able to be moved as safely as possible in all constellations – safely for people, the crane environment and the loads themselves.

 

CRANES AND THEIR TYPES – A BRIEF OVERVIEW

Forklift trucks come in very different designs. However, they all share a large number of important and cross-design features. The situation is different for cranes. The range of different designs for these systems is much broader. There are over 30 different crane types in total. They are divided into free and limited-movement designs as well as powered and manual systems. There are also many different designs within these classifications.

To put it very simply, however, many cranes can be divided into four main classes:

• Traveling cranes: A crane system that is based on a largely free-moving and usually self-propelled substructure – although there are also traveling cranes on trailers or those that use a truck as a base (such as those we use). However, there are also specialized complete systems. Such models are among the most powerful mobile cranes.
• Tower cranes: The best-known type of tower crane is probably a typical construction crane made of steel truss structures. These are usually set up (semi-)permanently at one point and can therefore only move within the radius of their jib during operation.
• Gantry cranes: They are similar in design to a gate and usually move on special track sections – although there are a few trackless systems, for example in container handling. This design is further subdivided into gantry cranes, where only one trolley can move at right angles to the direction of travel, and those on which a slewing crane with jib is mounted.
• Overhead cranes: They are similar to gantry cranes. In contrast to these, however, they are found almost exclusively in halls. In addition, the crane consists only of the horizontal bridge. The girders are not movable, but are designed as fixed high rails on which the bridge moves. Typically, only one trolley is available here.

These four examples provide a superficial insight into the variety of different types. The complete subdivision with all super- and subgroups is much more diverse.

ABOUT THE DIFFERENT DANGERS WITH CRANES

In principle, the tasks of a crane can be summarized as follows: They move loads in a three-dimensional space. However, this not only results in impressive potential, but also risks within the operation. These include, for example

• The vertically acting force of the load overloads the system. Put simply: The load is too heavy or otherwise unsuitable to be safely lifted vertically upwards from its location.
• The crane system is overstressed by the longitudinal or transverse movement of the load. For example, because the horizontal movement is decelerated too quickly. In this case, the moment of movement of the load hanging on the rope or chain is decelerated much more slowly than that of the crane itself. It continues to swing, causing centrifugal forces, among other things, which can lead to the crane tipping over, for example.
• The crane itself or the load is not operated with sufficient focus on the surrounding conditions. When operating a crane, it is not only obstacles or site boundaries that need to be taken into account, but also wind conditions, for example. The crane or load can get out of control and quickly cause millions in damage and pose a risk to life and limb.

In contrast to mobile systems, the risks associated with permanently erected cranes are somewhat more manageable, as only the load itself, the capacity of the crane and its speed of movement need to be taken into account. The ground and any rail and other movement systems have already been optimally laid out before the crane is erected.

For semi-permanently erected cranes (such as tower cranes on construction sites) and all mobile cranes, however, the variable ground is an additional imponderable factor. Before positioning the crane, the load-bearing capacity of the ground must therefore be checked and optimized if necessary.

From this point of view, a universal basic rule applies, especially in the open air:

 

Crane spaces must be compacted

If this phrase is familiar even to non-experts among our readers, it is most likely because it has become very well known thanks to a viral internet video. In the clip, the operator of a mobile crane is extremely eloquent about the lack of preparation of a site on which he is supposed to work with his mobile crane. However, this does not change the basic accuracy of the sentence.

It must also be ensured that the crane can be aligned completely horizontally. If the vehicle is tilted, this can lead to one-sided loads that make operation extremely unsafe.

ON THE TRAINING AND SUITABILITY OF CRANE OPERATORS

Cranes are among the most important work equipment in many companies. As they are used on almost every major construction site, their statistical share of accidents at work is very high in relative terms.

However, the ratio of technical errors to human error is striking – because the latter in particular is behind a relatively high number of avoidable accidents at work. Misconduct on the part of the crane operator is often the cause. The crane operator is the key person who decides on the safe operation of cranes.

For safety reasons, only those persons who have a crane operator’s license are permitted to operate a crane commercially – further details can be found in DGUV Principle 309-003. First of all, basic personal suitability is important. A crane operator must

• be at least 18 years old,
• have the physical and mental aptitude to operate the crane independently,
• have been demonstrably instructed in crane operation and
• be generally suitable for the reliable performance of the tasks assigned to him.

Colloquially, the official aptitude requirement is referred to as “the crane certificate” in the singular. In fact, however, the aforementioned DGUV principle states that there are differences in the scope and therefore duration of the instruction – depending on the type of crane for which the training is to be provided.

• Partially powered cranes: 1 day
• Floor-operated cranes: 1 to 5 days
• Cab-controlled cranes: 5 to 10 days
• Tower cranes: 10 to 15 days
• Mobile cranes: 15 to 20 days

Although these figures are only experience-based guidelines, they are a very good reflection of the amount of training required, which increases with the complexity of the crane in question. For special cranes and/or very challenging loads, the (advanced) training can also be significantly longer and more extensive.

THE MOST IMPORTANT BASIC RULES FOR AVOIDING SICKNESS ACCIDENTS

The legal provisions mentioned at the beginning are extremely detailed in their overall structure. However, the day-to-day safe handling of all types of cranes can be broken down into a few basic rules. These should be the starting point for all further, more detailed and model- or type-specific safety rules:

1. The crane as a whole must be in a proper condition (in accordance with the manufacturer’s specifications and the law) before work begins. To this end, the crane must be inspected regularly by experts as specified in DGUV 309-001. The definition of the word “regularly” can be interpreted differently depending on the type of construction. Furthermore, as specified in DGUV 209-012, the crane operator must check the function of the safety equipment and the general condition of the crane before each start of work (in case of doubt, at the beginning of each shift).
2. The condition of the load or its elements intended for crane operation (such as lugs or pallets) must meet the requirements for safe operation. The same applies to the load handling attachments used. These must be selected so that they correspond to the type of load, its mass and dimensions.
3. When using mobile cranes, all relevant parameters must be checked for safety before installation. The same applies to the loads to be moved on site. This primarily applies to the load-bearing capacity of the ground. However, any obstacles (such as power lines) and wind loads must also be taken into account. In addition, a safety zone must be defined around the working area and marked with suitable measures. The crane operator is responsible for all these measures.
4. The load should or must not (depending on the type of load suspension device) be guided over people.
5. The crane driver must ensure that the load is properly attached and may only move it if it is correctly executed.
6. Only one person agreed in advance with the crane operator is permitted. Hand signals must comply with DIN 33 409 “Safety-related work organization; hand signals for instruction”. If radio equipment is used, everyone involved must be able to operate it properly. Before starting work, the frequencies/channels used and alternative frequencies/channels in the event of faults must be defined. Furthermore, these must be tested for clear communication (under real conditions, e.g. crane operator in cabin, instructor at load pick-up point).
7. Load moment limiters and similar safety devices must always be set according to the relevant parameters and must never be overridden by measures taken by the crane operator (e.g. retracting/lifting the boom).
8. All loads must be moved with the lowest possible lifting height and speed in all three dimensions. All travel and other movements must be carried out in such a way that the crane operator can safely stop the movement at any time.

Cranes can not only be a key element for many tasks, but are often the only technical systems that can carry out the requirements with sufficient efficiency. Nevertheless, everyone involved should always be aware of the risks and the associated responsibility – regardless of whether a load of just a few kilograms is suspended from the hook or an aircraft with a mass greater than that of a ready-to-take-off airliner.

 

 

Image sources:

Image 1: stock.adobe.com © bannafarsai

Image 2: stock.adobe.com © Blende-8

Image 3: stock.adobe.com © zorandim75

Image 4: stock.adobe.com © nordroden

Image 5: stock.adobe.com © Friends Stock