Carry A Heavy Load
What is a Load Test and why is it so important?
When it comes to overhead cranes, safety is critical.
A load test is a literal testing of limits. Pushing a crane beyond it's rated capacity under controlled conditions to expose any flaws or breaking points, so that any repairs can be done.
When a new overhead crane is installed or if any physical changes have occurred to the crane system itself, a series of weight assessment protocol is mandatory for the safety of all workers and employees. Occupational Health and Safety requires a Load Test Certificate before the crane can be put into regular use.
You can read more on the OH&S requirements here.
How It Works
When a crane is first designed, an engineer will decide what rate of deflection (bend) both the bridge and runways are safely able to bear dependent on the size, length and design of the crane.
Once installed, a technician will then load the crane to 125% of it's rated safe working load capacity. (ex. if rated for 5 tons, a load of 6.25 tons will be applied). This is usually accomplished with the addition of rated steel test weights or in some cases, such as sizable port gantry's, water weights are the convention.
While under the additional burden of weight, the bridge and runways will then be measured, using the proper equipment, to see if the amount of deflection in the steel falls within the safe parameters laid out by the original engineered design.
The crane will also be tested to see that all functions are working correctly. A complete check of hoisting, lowering, trolley travel, bridge travel, limit switches as well as locking and safety devices will be completed under the extra stress.
This also allows the technician to determine and verify any load limit switches to proper and safe settings.
Why It's So Important
When steel is under pressure it can expose many hidden problems, such as damaged weld seams or frame segments. Many underlying concerns that could lead to issues, including catastrophic failures down the road, will be brought to light during a load test which can be rebuilt or repaired before the equipment is put into use.
For more information on Kristian's load testing and preventative maintenance click here.