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Our Testing’s in the (Water) Bag | #TrainingTuesday



We’ve covered the importance of pre-use checks & inspections on the Hercules SLR blog before, like visual inspections, proof-testing and non-destructive testing – One thing we haven’t covered, however, is what water bag proof load testing is and why we do it here at Hercules SLR.

So, to start—What’s a water bag, anyway?

Well, it’s a little less exciting than a water-ballon (only a little bit, promise) and is a method used to proof load test cranes that uses water instead of traditional, solid weights.

There are quite a few benefits when you load test with a water bag versus traditional, solid weights. But what are they? In this article, we’ll cover:

  • What water bags are used to test for
  • The benefits of using water bags
  • Useful hardware for securing & rigging a water bag
  • Safety tips


Water bags testing is for:

  • Cranes
  • Lifeboats
  • Elevators & conveyors
  • Load-bearing structures & lifting equipment
  • Counterweights
  • Bridges


What are the benefits of using water bags to test crane strength? Well, there is: 

  • If you’re close to a water supply. water bags:
    • significantly reduce transportation costs, storage and handling issues
    • rigging time
    • overall expense
    • test load applied gradually and precisely
    • problems identified and dealt with long before max. load is reached, and allows for safe controlled environment during testing conditions.

Water bags are best used with spreader beams for offshore application. If you’re operating a crane or any piece of hoisting or lifting equipment, you must test it before using it for anything.

A proof test is a test used to check the condition of any load-bearing structure. Often, during a proof test weight is applied beyond the working load limit to test how much strength a structure, like a crane, can truly take—This is important in case the crane is someday loaded beyond capacity.


So, what kind of equipment should you use with a water bag? Here’s some rigging equipment that might help you to secure the load:

  • MasterLink
  • Round Sling(s)
  • Shackles (Various or specific types of shackles may be required to secure the water bag—Check with manufacturing/provincial regulations to make sure your rigging complies).
  • Lifting straps


  • Don’t load bags beyond the working load limit (WLL)
  • Use a calibrated monitoring device to measure the load of the water bag
  • Remember, the water bag is considered the load, not lifting equipment & the lifting set for the water bag is separate—Keep this in mind when using water bags to test load-bearing structures.
  • Optimal water bag design has a load carried by the web lifting set, not through the bag’s material.
  • Be sure to perform a risk assessment before you test a crane or other load-bearing structure with water bags—There are instances that a water bag will fail, and riggers and nearby personnel must have a plan in place if failure occurs.
  • Inspect water bags before each use
  • Do not hang more than three water bags from a single attachment point