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How to Test Lifting Magnets?

Posted on May 22, 2017

lifting magnet with load underneath

Prior to managing any material handling equipment, proper steps to testing must be carried out especially there are always heavy loads involved. All permanent lifting magnets must pass the requirement stated in ASME B30.20. compliance for the close-proximity operated magnets.

All lifting magnets, either newly purchased, altered or refurbished, need to be tested by trained knowledgeable examiner before using them. Such tests must be formally documented with performance date, detailed areas of inspection and any steps of corrections. During the testing, inspector need to check for any noticeable defects or malfunctions, especially the safety latch, handle, hoist ring, bottom face and safety marking. If there are electrical indicators, controls, or alarms involved, make sure they are all working effectively especially if they are built-in emergency warning signals.

A breakaway-force test must be performed on all lifting magnets and must exceed their corresponding rated lifting capacity by a factory of more than 2. It is the breakaway point when the lifting magnet being vertically pull away from a flat, clean, low-carbon steel plate with a minimum thickness of 3 inches. It is noted that any slight tilt away from the vertical angle may yield a lower value and the full bottom face of the magnet must touch the flat load during the test. If your lifting magnets are meant for a unique working environment, keep in mind that these special conditions will have a derating factor. Any surface roughness, unevenness, dust, small thickness or elevated temperature (above 148oF) in the contact area with the lifting equipment will decrease the tested rated lifting capacity. Based on the ASME B30.20., “the portion of this plate in contact with the magnet shall have a 125- µin. (3.2 x 10-3 mm) finish and be flat within 0.002 in./ft (0.05 mm/m), but not exceeding 0.005 in. (0.127 mm) total.” Armstrong offers recertification service at very low price, contact us for service details and price.

Safety should be the priority of any steel working environment. Operational and maintenance teams must work together to come up with a well-thought-out checklist for the testing. Armstrong Magnetics can always provide technical assistance if required. All Armstrong NL-B series magnetic lifting devices are designed and manufactured with a breakaway-force standard of minimum 3 times of rated load capacity. We are always conservative on our model recommendations to ensure greater lifting safety factor.