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How the “Bend But Don’t Break” Principle Applies to Tubular Drag Conveyors

If you’re a sports fan, you know that the term “bend but not break” refers to a football defense that gives up yardage but doesn’t allow the opponent into the end zone. If you practice yoga, you’re probably familiar with the concept of “I bend so I don’t break” as it applies to both physical movement and a general approach to life.

If bulk material handling is an integral part of your operation—and your requirements for conveying systems include unique layout configurations around bends and over multiple levels—you are (or should be) aware that in the vast majority of applications, the tubular drag conveyor is the best option. The simple fact that this type of conveyor can include bends and change planes allows it to do what other conveyors cannot. A single tubular drag conveyor can also potentially do the work of several conveyors, and thus can have a lower operational cost in the long run.

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This is where the “break” aspect comes into play. All material handling equipment will eventually experience wear, especially in applications that deal with abrasive material (another specialty of the tubular drag conveyor). Chain-type tubular drag conveyors are robustly built for outstanding reliability in demanding industrial environments and any other operation where uptime is critical. However, the addition of bends naturally increases chain pull (a.k.a. the amount of energy needed to pull the chain though the circuit). As chain pull increases, so does the potential for wear; as wear increases, so does the potential for maintenance headaches and equipment failure.

There are several ways to reduce the potential for wear in a tubular drag conveyor that calls for bends in the configuration:

1. Minimize the number of bends.

Tubular drag conveyors are capable of multiple changes in direction, but the most reliable circuits contain no more than 270° of bended pipe. The actual number of bends that can be included also depends on where they are located in the circuit and whether the conveyed material behaves as an abrasive or a lubricant.

2. Use flights made with durable material.

Depending on the need, conveyor flights can be made with various materials that are more durable than plastic, including steel, aluminum, cast iron and polyurethane. However, unless special circumstances such as high temperature prevent their use, we generally recommend and supply UHMWPE (ultra-high molecular weight polyethylene) flights. UHMW is an engineered material that is abrasion and impact resistant. It is also lightweight and has a very low coefficient of friction, which minimizes wear to bends and pipes by reducing the energy required to pull it through the conveyor circuit.

3. Avoid using round-link chains.

As mentioned previously, one of the biggest advantages of tubular drag conveyors is their ability to change directions. The success of this equipment in a configuration that requires bends or any kind of conveying length is largely dependent on chain type. Due to the weakness of round-link chains, they must use roller turns in the corners to reduce the load on the chain. Roller turns are often placed on the “carrying” run, which is the side of the conveyor that carries the material. Unfortunately, this placement allows material to flow through the mechanical assembly, where it can cause excessive wear on the assembly, damage the material being conveyed, or create material build-up in the conveyor, which is difficult and time-consuming to remove.

At Hapman, we recommend using engineered chains in tubular drag conveyors that have bends in the circuit. These chains are designed with enough strength to withstand the increased loads in the corners. Therefore, they do not require roller turns, which effectively eliminates any performance or maintenance issues associated with material entering the conveyor’s mechanical assembly. This is just one of the advantages of using engineered chains in tubular drag conveyors; you can read about the rest of them in this blog and in this white paper where we make the case for engineered chains over round-link chains.

While the shortest distance between two points is a straight line, such a configuration is not always possible when conveying material. That’s why tubular drag conveyors from Hapman are in demand. Not only do they use less energy than other conveyors to move challenging materials in a completely sealed system, but our design expertise combined with more durable flights and chains results in a material handling solution that can “bend but not break.”