This article mainly centers around a type of below the hook lifting equipment – magnetic lifting device and relevant safety practices and guidance on risk assessment and control, inspection & maintenance.
Party I: Things that should be taken into account in the risk assessment of magnetic lifting device
Rating of magnetic lifting device – the weight of the magnet and its accessories should be taken into account when assessing the load carrying capacity and safe operation of that lifting equipment.
Protection against lifting excess material – When lifting plates from a stack, the magnetic field can be such that more material than required is magnetised, with those items furthest from the magnet liable to be easily displaced. A reduced-power or similar facility can be used to avoid lifting excess material. Restoring the full power secures the remaining load.
Magnetic lifting device attached below-the-hook of overhead crane – overhead cranes have to contend with the weight of the magnet and also the inertia effects during slewing and travel. Consideration also needs to be given to the effect if the load were to be suddenly released before it has been grounded. Guidance should be sought from the crane manufacturer when the use of a magnetic lifting attachment is being considered. The manufacturer may advise against using a magnetic attachment or require de-rating the normal SWL(safe working load) when using magnets.
Lifting of bundles – Where magnetic lifting devices are used to handle bundled materials, it is essential that appropriate risk control measures are in place to protect people, plant and equipment from the risk of falling material. In particular:
•The magnetic equipment used must be suited to the task;
•Magnetic lifting devices should not be used to lift bundles of materials unless the banding is rated for lifting duties (i.e. it is marked with a SWL). Standard banding wire/straps used to restrain loads during transit should not be relied upon for lifting duties.
•All persons should be prevented from entering any area where they could be injured if a bundle broke apart during lifting/handling.
Speaking of close proximity to the lifting load, there’s another type of magnetic lifting device, remote control lifting magnet, which is perfect for getting rid of the risk of personnel injury caused by getting too close to the heavy sharp load. All magnetic lifting systems from HVR MAG, are provided with radio remote control.
Part Ⅱ: Inspection & maintenance for magnetic lifting device safety
The manufacturer’s instructions for the regular inspection and maintenance of the magnetic equipment should be followed. Where appropriate, inspection and maintenance schedules should include:
▶power cables to the magnet – check for damage and ensure that they are properly supported
▶magnet assembly – check for damage to the suspension points and that retaining bolts are kept tight
▶magnet face – check for any damage to the face which might affect performance
▶magnet – check for deterioration of insulation resistance; check the value of coil resistance to ensure that “inter-turn” faults have not developed whilst in use
▶electrical plug and socket connectors – check that mechanical strength, insulation and electrical conductivity are being maintained
▶lifting accessories e.g. chains, links etc associated with the magnet – thoroughly examine at appropriate intervals
▶back-up batteries – check their condition and that the battery back-up alarm works when the power is off.
▶control boxes/pendants – check for damage, legibility of control labels, correct function of controls including audible and visible warning devices.
▶Magnetic adhesion – periodic verification by inserting a ‘test piece’ of non-metallic material between the magnet and the material. It should still be possible to pick up the load with the test piece inserted.
Learn more about magnetic lifting device, ie their safety features, applications, welcome to visit our website for a better understanding: https://www.hvrmagnet.com/category/electro-permanent-lifting-magnets-1.html
