Operations Team
Marine cranes, davits, and lifting appliances are subject to some of the most grueling environmental and operational conditions on Earth. To ensure safe cargo operations and compliance with international maritime laws (such as LOLER and SOLAS), rigorous crane load testing must be performed at strict intervals.
Why is Load Testing Mandatory?
Lifting equipment aboard a vessel degrades over time due to saltwater corrosion, metal fatigue, and hydraulic seal wear. A load test is a practical proof of strength, verifying that the crane, its foundation, and its braking systems can safely handle their rated Safe Working Load (SWL) without catastrophic structural failure.
The Shift from Solid Weights to Water Weights
Historically, shipyards and surveyors used massive solid steel or concrete blocks to test cranes. Today, the industry standard has shifted heavily toward Water Weight Bags (Air Lifting Balloons).
- Safety: If a crane fails during testing with solid weights, the sudden drop of tons of steel can fracture the hull or injure personnel. Water bags burst or can be rapidly drained, minimizing kinetic impact.
- Logistics: Empty water bags weigh only a few kilos and can be easily flown or transported to remote anchorages. They are then slowly filled with seawater via pumps.
- Gradual Load Application: Water bags allow engineers to slowly incrementally increase the weight to exactly 10%, 50%, 100%, and 110% of the SWL, easily spotting minor structural deflections before a total break occurs.
The Testing Procedure
A standard 5-yearly Proof-Load test generally encompasses:
- NDT Inspection: Prior to loading, all critical welds, slewing bearings, and pins undergo Magnetic Particle or Ultrasonic Flaw Detection.
- Static Testing: The load is applied and held stationary to test the integrity of the hydraulic brakes and holding valves.
- Dynamic Testing: The crane operates through its full range of motion (hoisting, slewing, luffing) while under load to ensure motors and hydraulic pumps can handle the stress.
"A crane failure at sea doesn't just damage cargo; it can cost lives. Never compromise on your 5-yearly load testing routines."
Leon International provides fully certified crane load testing using state-of-the-art water weight systems and certified calibrated digital load cells. Our tests are attended and approved by major IACS classification societies.
