For lift technicians, the summer and fall months can be just as busy as cold, snowy winter mornings. There’s a lot of inspection and testing that goes into maintaining a lift. The ANSI B77 standard, the standard governing lift maintenance and operations, is the driving force behind a lot of what must be done.
A little three-letter acronym may be one of the most important aspects of the B77 standard. That acronym is NDT, which stands for “Nondestructive Testing.” NDT consists of a wide array of analyses and scientific techniques used to evaluate or examine properties of materials, components, or systems, without destroying the materials or the system itself.
In the case of the ski industry, nondestructive testing helps identify and eliminate areas of fatigue in our machines, including chairlifts. And when talking about chairlifts, fatigue means repeated action leading to the weakening of a component. For a simple example of fatigue, think of bending a paper clip over and over until it snaps.
As a lift system operates, fatigue is introduced to almost all components over time. Fatigue leads to cracks, and if the cracks get big enough, they become visible to the naked eye. If left unattended, these cracks can grow until they cause a failure in the component. Our goal with NDT is to identify those cracks as early as possible. Some techniques can detect cracks before they can be seen with the naked eye. In all cases, the aim is to spot fatigue before it reaches the point of causing a component failure. To do that, we need to employ both basic and advanced NDT techniques.
Visual inspection is the most basic NDT process, and the ski industry utilizes visual NDT in its everyday operations. In many instances, both maintenance and operations staff look over the lift components on a daily basis. Examples include pre-operational logs and inspections of the carriers, rope, braking systems, and tension systems.
However, more advanced techniques are required to identify non-observable signs of fatigue. One example is identifying broken wires on the inside of the haul rope, which can be done by using a magnetic rope test. To determine if something is corroding from the inside, such as a 35-year-old lift tower, ultrasound (sound waves) can reveal the thickness of the steel.
These techniques require an experienced NDT technician with specific training and skills. Most manufacturers and industry standards require a person to be Level II certified to perform more advanced NDT techniques. This certification requires several days of training, nearly 500 hours of NDT experience, and 200-300 hours of training with a particular method.
According to the ANSI B77 standard, 20 percent of the grips and carriers on each lift must be inspected per year. In other words, if a particular lift has 240 carriers, then 48 of them must be inspected annually. Some of the inspection is conducted visually, and some is done via advanced techniques. Utilizing dye penetrant in critical areas is one example. When a liquid dye is sprayed on a component, the penetrant collects and stays in any cracks; when the area is wiped clean, the issue is revealed.
Most common NDT techniques involve magnetizing a grip part, then using either a colored iron dust powder or liquid revealer. The dust or revealer flows over the part and settles in any crack the part may have. A strong black light in a dark room is used with the revealer, as detailed in the photo on p. 18. If problems are found, the manufacturer may require NDT inspection of all the carriers and/or grips.
There’s another instance in which more-frequent testing is required: if your lift operates all year long and exceeds a maximum of 2,000 hours of operation. In this case, testing of 20 percent of the grips is required every 2,000 hours. Lift manufacturers also play a role in determining the kind testing to be done, and how often testing must take place.
Nondestructive testing, in all of its forms, is preventative care that is critical to the overall safety for your resort. That’s just one reason that summer and fall continue to be busy for our lift operations and maintenance teams.