Importance of Periodic Load Testing

You might check your crane daily, but can it actually lift its rated capacity? Visual inspections can spot cracks and wear, but they cannot verify the structural integrity under load. This is where Load Testing comes in.

What is a Load Test?

A load test involves lifting a test weight that is heavier than the crane's Safe Working Load (SWL) to prove it can handle the stress. This is typically done using certified test weights or water bags.

Types of Load Tests

1. Proof Load Test (Initial)

Performed when the crane is first installed or after major repairs/modifications. The load is usually 125% of the SWL.

Example: A 10-ton crane is tested with 12.5 tons.

2. Periodic Load Test

Performed annually or as required by local regulations (e.g., OSHA, LOLER). This verifies that the crane hasn't degraded over time.

Why is it Mandatory?

• Hidden Defects: Internal cracks in gears, shafts, or welds may not be visible to the naked eye but will reveal themselves (safely, hopefully) during a controlled test.
• Brake Verification: The test ensures the brakes can hold the load without slipping.
• Limit Switch Check: Overload limiters are calibrated during this test to ensure they cut off power at the right moment.

The Procedure

1. Pre-Test Inspection: Check ropes, hooks, and structure for obvious damage.
2. No-Load Run: Operate all motions without weight.
3. Light Load Test: Lift a small weight to check stability.
4. Rated Load Test (100%): Lift the full SWL and move it through all motions.
5. Proof Load Test (125%): Lift the overload weight. Hold it for a specified time. Check for deflection and brake slip.
6. Post-Test Inspection: Check for any permanent deformation or damage caused by the test.