Many ‘Pump Problems’ Aren’t Pump Problems

This article was inspired by a long drive home from a jobsite, thinking back on several recent troubleshooting calls I supported. What occurred to me was that none of them were true “pump” problems. Every issue traced back to installation mistakes—specifically, how the pump was mounted to the foundation.

These were simple mistakes, but correcting them cost thousands of dollars in additional labor, travel and materials. In this column, I’ll point out a few common issues I see repeatedly that are easy to avoid to ensure a solid installation.

The pump baseplate, grout and foundation are intended to form a single, monolithic structure that provides a flat, level surface for mounting the motor and pump. Together, they should act as one mass to absorb the static and dynamic forces applied to—and generated by—the motor/pump assembly. When these three components are not bonded into a single mass, alignment and vibration problems begin to appear.

The first area that often needs attention is surface preparation. Start with the top of the foundation where the pump will be mounted. A beautifully smooth, highly finished slab does not allow grout to bond well. As shown in Image 2, the surface must be roughened to give the grout “tooth” to grip. Once roughened, remove all loose material and dust. In some cases, the surface needs to be cleaned to remove grease or oil that prevents proper grout adhesion.

The next preparation area is the underside of the pump baseplate. Whether the pump is refurbished or brand-new, any surfaces that will contact grout should be cleaned—and, if required, primed—to promote a strong bond. Machining fluids and rust can become weak points that allow the grout and baseplate to separate, leading to vibration, alignment problems and potentially additional corrosion. Thorough cleaning and priming of the baseplate underside can help prevent these issues.

Another common installation issue is the use of leveling nuts on the foundation bolts (Image 1). If leveling nuts are used and there is no provision for loosening them after the grout is poured, the bolt will not be in proper tension between the foundation and the hold-down nut. Instead, the baseplate is simply clamped between two nuts, one below and one above. This condition can allow the foundation bolt to vibrate, eventually loosening and allowing the baseplate to separate from the grout. Note: This method is used extensively in signage and building structural elements, but it is not acceptable for the high vibration levels in rotating machinery.

My last caution concerns wedge-type concrete anchors. These are popular because they simplify foundation work by eliminating the need to accurately set anchor bolts during the pour. When installed correctly, they perform well. The issue I most often find is poor hole cleaning: If the drilled hole is not thoroughly cleaned, the anchor may never fully expand and develop the tension needed to hold the baseplate down. Proper, thorough cleaning of the drilled hole is essential for these fasteners to work as intended.

An excellent way to properly install a pump baseplate is illustrated in Image 2. After completing the surface preparations described above, use jacking screws (as shown) to level the baseplate; this provides excellent control of baseplate flatness. Once the grout is poured and cured, back out the jacking screws and tighten the hold-down nuts. Proper bolt tension then locks the foundation, grout and baseplate together, creating the monolithic support we are looking for.