One of the most common repairs on centrifugal pumps is replacing worn or damaged wear rings. To restore efficient, reliable operation and prevent catastrophic pump failure, it is critical to restore proper clearances between the stationary casing wear ring and the rotating impeller wear ring. Although many pump manufacturers provide clearances and dimensions, some do not. There are plenty of aging pumps around from now-defunct manufacturers for which dimension data is simply not available.

In such cases, the rule of thumb that follows provides some guidance for acceptable running clearances, or the minimum running clearance chart in American Petroleum Institute (API) Standard 610 can be used as a guide.

The repair of the various types of pumps represents an important segment of the service center repair market. Electric motors and pumps are the two most widely used industrial machine components.                                                                                                                                                                                                                       

Although there are two principle pump types (dynamic and positive displacement), this manual focuses on dynamic pumps and the fundamentals of dynamic pump repair. The information it contains will be helpful to both novice and experienced pump repair technicians, to supervisors and managers of pump repair operations, and to customer service and sales personnel who communicate with customers about pump repair issues.

Submersible pumps may have any of several types of internal sensors or protective devices. These may include temperature sensors, vibration transducers or moisture sensors. The type of temperature and vibration devices are identical to those used in non-submersible style motors, so only the moisture sensors are of special interest regarding submersible pumps. It is important for technicians involved in the repair of submersible pumps to be aware of their presence in any specific pump they may encounter, and understand the manner in which they function to ensure they work properly after repairs are completed.

High vibration is a common problem for motors that are installed on top of vertical pumps. Its source can be a mechanical issue with the pump, motor or coupling or even hydraulic forces from the pump.

Anyone dealing with installed machinery, or even test running motors in the service center, will encounter instances where structural resonance is amplifying machine vibration. The machine may meet stringent specifications in one instance but exceed acceptable vibration levels in another. A good understanding of natural frequencies and the tests necessary to identify them will help solve these vexing situations.

Vertical turbine pumps (VTPs) are workhorses in the petrochemical, power generation and manufacturing industries, and prolific in municipal water applications that handle the primary intake load. Although these machines are ruggedly built, abrasive sediments in the pumpage take a toll, particularly on line shaft and pump bowl bearings, so periodic overhauls are often necessary. Rather than simply replacing the bearings, however, it is important that repairs address all of the issues needed to restore maximum operating life.

As with most other machines commonly repaired in EASA service centers, dynamic balancing on pump impellers is an important concern. Excessive imbalance imparts forces on bearings, reducing their lives and subjecting machine mountings to vibratory energy that deteriorates foundations.

Las bombas sumergibles pueden tener diferentes tipos de sensores o dispositivos de protección internos, los cuales pueden ser sensores de temperatura, transductores de vibración o sensores de humedad. Los sensores de temperatura y de vibración son idénticos a los utilizados en los motores no sumergibles, por lo que solo los sensores de humedad guardan especial relación con las bombas sumergibles. Es importante que los técnicos involucrados en la reparación de las bombas sumergibles sean conscientes de su presencia en cualquier bomba en los que se puedan encontrar y que comprendan como trabajan para asegurarse que funcionan correctamente después de terminar los trabajos de reparación.

Al igual que con la mayoría de las otras máquinas reparadas comúnmente en los centros de servicio de EASA, el balanceo dinámico de los impulsores de las bombas es una cuestión importante. El desbalanceo excesivo imparte fuerzas sobre los rodamientos, reduciendo su vida útil y sometiendo los soportes de las máquinas a una energía vibratoria que deteriora las fundaciones.

A special discounted collection of 8 webinar recordings focusing on various aspects of pump repair.

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