Non-Destructive Testing: More Than Meets the Eye

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Everyone using rigging gear should know how to visually inspect and measure it for the following items:

  • Wear  
  • Broken strands 
  • Hook throat opening 
  • UV or temperature damage 
  • A readable capacity tag that matches sling size  
  • Check end fittings for safe use 

In addition to visual inspections and taking measurements, another valuable practice is to conduct Non-Destructive Testing (NDT). The type of NDT may vary with the jobsite and equipment in use. Common types include Magnetic Particle, Ultrasonic, Eddy Current, Radiography, Acoustic Emission, Dye Penetrant, and Leak Testing.   

Magnetic Particle Testing is one of the most common types of tests for the cranes and rigging gear, which is routinely conducted on crane hooks and wedge sockets. A magnetic particle testing yoke is easily portable and can detect cracks or shallow, sub-surface imperfections. Typically, magnetic particle testing is conducted in conjunction with crane and rigging inspections and helps identify flaws that may not be visible on the surface.  

Knowledge of how, and when, to properly use a magnetic particle test is essential. Individuals conducting NDTs should also have knowledge of cranes, rigging gear, components, and be a qualified NDT Technician. The inspection technician should have the expertise, tools, and technology to conduct the NDT and the inspection in a manner that does not alter the future usefulness of the test object.  

As always, buyer beware of “home remedy testing” from an individual, or anyone not using materials that are specifically formulated for NDT. The person conducting the NDT must always be qualified.  

Another form of NDT is ultrasonic testing, which is more in depth, and can reveal subsurface dimensional flaws, and internal weaknesses. Ultrasonic testing is used if a job site requires it, or if a flaw is suspected.  

Magnetic Analysis Corp. explains that “Ultrasonic waves create a mechanical vibration or pressure . . . usually from 1MHz to 30MHz and is designed to test without damaging the test objects. Two methods of Ultrasonic testing used for flaw detection are – Shear and Compression Wave. 

  • Shear method uses an angled beam that is usually 45 degrees. This enables surface and subsurface testing. With the shear method, surface cracks, seams, and near surface inclusions can be detected. Shear method can overlap the normal incidence method inspection and result in a 100 percent volumetric test of the bar. 
  • Compression is also known as normal incidence. This is the primary internal inspection for bar testing.  

So, how do you know which type of testing is necessary? As usual, the demands of the job, and the conditions warranting an NDT dictate the skill and equipment needed. Magnetic particle testing costs less to conduct. However, if you are in doubt about the reliability of the equipment or component, Ultrasonic testing is far less expensive than a failure during service.