Parts made of these materials can help solve some common pumping problems.
by John A. Kozel

In a market full of product choices at different prices and quality levels, structural composite engineered aftermarket solutions can offer end users value-added alternatives to some imports. Engineered aftermarket parts can provide longer life, lower operating costs, reductions in energy costs with a healthy return on investment (ROI).

Instead of repairing a pump, or replacing the old pump with a new pump of the same type or quality, many aftermarket engineering companies offer the end user better solutions in the form of longer-lasting products and parts.

graphite impellerImage 1. A machined structural graphite composite impeller (Images courtesy of SIMS PUMP Valve Company, Inc.)

Fortunately, today there are specialized aftermarket engineering companies manufacturing machined structural engineered pumps, impellers, rings, sleeves, bearings, bushings and mechanical seals, which are computer engineered, designed, and precision machined (not cast or molded). These companies have the objective of maximizing longevity, reliability and energy savings.

Structural Composite

Aftermarket structural composite upgrades can improve performance, maintenance and repair issues. They improve efficiency as well, so they can extend pump life and reliability. Structural composites offer the additional advantages of strong mechanical properties as well as being lightweight and resistant to corrosion, erosion and cavitation.

By installing these structural composite aftermarket products into existing pumps or pumping systems, the end user can realize life cycle and monetary savings. The implementation of these pumps, impellers, rings and pump parts directly contributes to an increase in pump efficiency. These parts can also help eliminate electrolysis, rotor imbalance, premature bearing failure, and leakage between the wear rings, casing rings and interstage bushings. These detrimental occurrences can destroy metallic pumps and pump parts leading to inefficiency and an increase in energy consumption.

In difficult times, it may be hard to allocate the funds for additional upgrades. However, in almost all cases, the incremental costs of upgrades are minimal when compared to the funds lost in downtime and expensive repairs.
Structural composite aftermarket engineered solutions for pump applications can be purchased on a quick delivery basis. Aftermarket engineered solutions are also good alternatives for replacement upgraded parts for old or obsolete pumps. Engineered aftermarket companies specialize in solving pump problems such as imbalance, cavitation, corrosion, electrolysis, erosion and radial-thrust problems.

Upgrading existing pumps with qualified structural composite components can reduce energy costs. Structural composite impellers and rings can be re-engineered to operate at the best efficiency point (BEP). Composite products do not corrode in seawater, wastewater, sewage or chlorinated water, so the efficiency does not deteriorate over time. Structural composite pumps, impellers, rings and other pump parts are designed with computational fluid dynamics (CFD) techniques to maximize efficiency. The impellers are precision machined from one center position and therefore ideally balanced.

System Optimization

An all too common problem occurs when a user purchases a pump for a specific performance but, due to changed system requirements, it operates at a point different than the expected BEP. In addition to being energy inefficient, operating the pump away from the original BEP causes a multitude of problems such as excessive noise and vibration of the pump, shaft oscillation and cavitation. It can also cause premature wear and failure of the mechanical seals, bearings, rings, sleeves and impellers. In extreme cases, the pump shaft will break behind the impeller from excessive radial forces.

Fortunately, these problems can be easily resolved by installing aftermarket engineered structural composite impellers and rings, which have been re-engineered for specific system requirements. Not only is the efficiency of the pump improved, but also the reliability and longevity of the complete pump is substantially increased.

Composites also help with the reduction of energy consumption and repair and maintenance in the area of shaft deflection. Some structural composite impellers and casing rings are only 15 percent of the weight of traditional metallic materials. The lower weight not only reduces start-up load, but also reduces shaft deflection, which allows the rotating element to run with tighter clearances between the rings and the impeller. The tighter ring clearance reduces leakage, which increases efficiency and reduces energy consumption. The reduction in shaft deflection increases efficiency and enables bearings, sleeves, mechanical seals and rings to last much longer, which saves on repair and maintenance costs.

Composite casing rings seal against the pump casing like a gasket and prevent pump wash out (damage to the casing from flow circulating behind the ring). Wear between the casing rings and the impeller wear rings creates large clearances, which result in substantial decreases in pump efficiency as well as increases in the energy consumed to operate the pump.

Historically, most pump companies and repair facilities have used metallic parts for wear rings and casing rings. These metallic parts have the potential to gall and seize. Metallic parts do not have self-lubricating qualities—unlike many structural engineered composites—and are subject to corrosion, which further increases clearances and energy consumption.

Composite Sleeves & Guide Bearings

Structural composite bearing and sleeve upgrades offer advantages when compared to metallic shaft sleeves and guide bearings. They protect the shaft, are lightweight and seal well against the O-rings of the mechanical seals. Wear between metallic rings and bushings creates large clearances and increases shaft deflection, which can decrease pump efficiency and premature pump failure.

Engineered structural composite sleeves and bearings defy corrosion in many environments and are preform well with most acid and alkaline solutions. Most composite sleeves and guide bearings have self-lubricating qualities, which allow for tighter clearances and prevent excessive shaft movement. Wear problems can be overcome by installing composite bearings, which also have friction-reducing lubricants. Additionally, the structural fibers in structural bearings offer high anti-galling characteristics.

Mechanical Seals

Composite seals incorporate lightweight, high mechanical strength, and superior corrosion resistance. Structural composite mechanical seal upgrades can provide a superior sealing design, which incorporates silicon carbide seal faces. The glands have an O-ring design for sealing against the pump casing, which enables the composite seal to be used on rougher surfaces or split-case pump housings.

By installing high quality alternative solution impellers and rings that have been re-engineered for specific system requirements, the efficiency, reliability and longevity of the complete pump can be substantially improved. Aftermarket upgrades can reduce maintenance and energy costs, proving to be a winning option when choosing your pump supplier.