Centrifugal pump OEMs claim they provide better parts, service, response and value than aftermarket service companies, but that isn’t always the case.
Until the early 1990s, OEM repair centers worked exclusively on their products, espousing the mantra, “We know our products best.” During the ‘90s, a decrease in new product sales caused OEMs to change their story and boast that their shops could work on any brand of centrifugal pump. Suddenly, their specific product knowledge applied to all centrifugal pumps.
According to the online magazine, World Pumps, six of the major U.S. centrifugal pump manufacturers of the 1980s have been consolidated into one, Flowserve. Many U.S. legacy brands are still manufactured by Flowserve. During the many mergers and acquisitions, the U.S. Department of Justice forced the sale of some brands to other manufacturers. Products were disassociated from their designers.
Before the great consolidation, each OEM had a chief engineer and several product designers who employed a holistic design process, which considered the whole product, the interaction of its various components, the user’s application and industry specifications. When a user had a significant problem, the chief engineer was called to sort it out. The lessons learned were incorporated into future designs and centrifugal pumps evolved over many years.
Industry standards, API 610 in particular, were developed by users to simplify procurement of quality equipment and to improve pump reliability. It is a compendium of users’ experiences, which are usually expensive experiences. API 610 captures solutions to common centrifugal pump design issues and best-in-class design features.
Computers loaded with amazing software have democratized engineering. When I was a design engineering manager at Pacific Pumps, I had physicists, mathematicians, metallurgists, engineers, drafters, document managers and a large team of people to create and distribute microfilm. In the early 1980s, we added a Fortran programmer to our staff. Today, that talent and many skill sets are on my desktop. Integral calculus is done with a click in MathCAD. Finite element analysis of structures, pressure vessels and even shaft keyways are integrated into our solid modelers. Hydraulic component design software feeds computational fluid dynamics analysis programs, reducing hydraulic design risk. Rotordynamic analysis software coupled with structural analysis tools solves — and hopefully prevents — vibration issues.
3D optical scanners and laser trackers provide accurate models of complex shapes. Conhagen can duplicate any pump case in one afternoon and improve it by the next week. It can produce a new case or impeller casting in five or six weeks. The development of patternless molds — 3D printed sand molds — was the game changer for Conhagen, yielding high fidelity, reasonable cost and quick delivery in most any metal.
Conhagen has evolved from a repair shop to a manufacturer that designs new centrifugal pumps or modifies existing pumps for specific applications. Unique designs provide the necessary hydraulic performance and mechanical robustness to minimize the total cost of ownership. Two examples of case replacements are included in this editorial — a four stage, axial split, boiler feed pump’s carbon steel case was replaced with a CA6NM casting. The second example is a single stage between a bearings pump that suffered rotor dynamics issues. Conhagen designed and manufactured a new case, shortening the distance between bearings from 37 3/4 inches to 30 5/8 inches.
Conhagen has been in business for 80 years. Its products include detailed engineering calculations, manufacturing drawings, installation, operation and maintenance manuals, a one-year operation warranty and support for management of change reports. It is big enough to be responsible, yet small enough to be responsive.
