This presentation focusses on critical close fit tolerances and certain surface finish specifications.

There are many considerations for selecting a barrier fluid in general, but only a few apply to submersible pumps. When the fluid specification cannot be found or when the specified fluid is not available for the repair, there are some general guidelines to follow that are offered here.

En general, existen muchas consideraciones para seleccionar un fluido barrera, pero sólo unas pocas aplican a las bombas sumergibles. En casos en que no se pueda encontrar o no esté disponible el fluido especificado para la reparación, este artículo ofrece algunas pautas generales que se pueden seguir.

Corrosion and/or erosion damage is inevitable for some pump applications. Pumps received for repair with significant damage may look like a candidate for the junk bin, but with proper repair techniques can often be restored to original performance – or perhaps better than original.

En algunas aplicaciones, los daños por corrosión y/o erosión de las bombas son inevitables. Las bombas enviadas para reparación que presentan daños significativos pueden parecer buenas candidatas para ser desechadas, pero a menudo con las técnicas de reparación adecuadas pueden restaurarse a sus condiciones originales o quizás a unas mejores.

It is commonly known that pump mechanical seals are temperamental devices that fail frequently. The fact is, mechanical seals are simple devices that are often misapplied, sometimes installed incorrectly, or perhaps installed on pumps that are not well suited for the application.

Para aquellos que son nuevos en el negocio de la reparación de bombas, los sellos pueden resultar intimidantes, sin embargo, es bien conocido que los sellos mecánicos de las bombas son dispositivos temperamentales que fallan con frecuencia. El hecho es que los sellos mecánicos son dispositivos simples que a menudo son utilizados de forma inadecuada, algunas veces instalados incorrectamente o tal vez montados en bombas que no son aptas para la aplicación. En la mayoría de las aplicaciones, los sellos mecánicos son lo suficientemente macizos para tolerar condiciones de operación y de manejo menos óptimas. Para aplicaciones exigentes todo debe estar bien.

Centrifugal pump failures are most commonly attributed to seal failure, impeller damage and bearing failures. A good understanding of failure modes for seals, impellers and bearings is essential to providing customers with reliable pump repairs.

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

Just $40 for EASA members!

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 pump repairs are completed! Now the pump needs to be tested. This presentation discusses the procedures for the basic tests that can be performed on pumps that have been repaired in the service center.

A leak rate of one drip per minute equals about a liter (quart) of water in three days. For an O-ring on a submersible pump, that is a major problem. O-rings are often used for static seals on submersible pumps. Understanding what makes a good static seal and what causes one to leak is important for pump maintenance and repair technicians.

For many larger centrifugal pumps, there are options for installing “component” or “cartridge” mechanical seals. Understanding the advantages and limitations of each will allow you to recommend the best solution for customer applications.

One drip per minute amounts to about a liter (quart) of water in 3 days. If that's the leak rate for an O-ring on a submersible pump, that's a big problem. O-rings are common for static seals on submersible pumps. An understanding of what makes a good static seal, and what causes them to leak, is obviously important for pump repair technicians.

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.

Split case pump seals are commonly the most difficult installation of any mechanical seal. The replacement of these seals usually is determined by the type originally found in the pump. The problem is that the existing seal type may not be the best for the fluid pumping application. The fluid to be pumped often is the last thing considered for a system designer specifying a pump for a general application. And if the fluid contains more than just water, problems can start to arise.

This presentation focuses on:

• Types of submersible pumps
• Tips on seal arrangements
• Common repair procedures
• Cables and cable entries
• Testing submersibles in the service center

Most centrifugal pumps today have mechanical seals. However, those pumps that still use packing glands instead of mechanical seals require frequent maintenance and are more likely to show up in the service center for repair. The average mean time between failure (MTBF) for mechanical seals is about 7500 hours. Packing glands require packing replacement after about 1,000 hours of operation. And the shaft or shaft sleeve for packing gland pumps is subject to wear, so pump overhaul to repair the shaft or replace the sleeve is inevitable. Improper installation or adjustment of packing glands can greatly accelerate wear, making much more frequent repair necessary. Replacing packing is not a technically demanding task. However, there are some tips that will improve the performance of the packing, limit the energy usage and extend the MTBF. Attention to these details will allow service centers to provide quality repairs for their customers.

Pump packing is a high maintenance item for any centrifugal pump so equipped, and unacceptable for chemical pumping applications. This paper covers how service centers can convert a pump from packing to mechanical seals.

This presentation focuses on:

• A review of seal basics
• Seal materials for primary and secondary seals
• How to determine spring tension values
• How to calculate PV values
• Seal flush plans

When talking with various pump manufacturers and mechanical seal suppliers, you're likely to encounter a variety of recommendations. (Some are complementary and some are contradictory.) With the variety of seal types, materials and pump designs, it is inevitable that what works well for one mechanical seal installation may not work for others. We will explain some good general practical considerations that will help service centers make judgments about the best techniques for the pumps they may encounter. Topics covered include:

• Non-pusher and pusher type seals
• Amount of spring tension
• Importance of a clean work environment
• Stationary face ring

An important part of submersible pump repair is ensuring the power and control cable is in good condition and that cables are properly sealed where they enter the pump.

For most centrifugal pumps, the shaft has packing or a mechanical seal where the shaft enters the wet end. Fundamentally, a sealless pump substitutes a magnetic drive for the shaft seal. The impeller shaft is fitted with a magnetic rotor which is contained in a thin metal cover. The shaft, impeller, the rotor and the bearings are all "wet" components; that is, they are completely submersed in whatever liquid is being pumped. Over the outside of the magnetic rotor and cover is a magnetic drum which is driven by the power source, usually an electricmotor. The magnetic coupling between the rotor and drum delivers torque to the shaft and impeller. There are a number of variations in design, but all use sleeve type bearings lubricated by the pumpage.

Most maintenance and operations personnel who work with centrifugal pumps have been warned to never start a pump unless it is primed. They have been warned that a pump that is started when loaded with air may cause the seal or packing to be scorched and permanently damaged, and that when the suction liquid level is below the pump (suction lift), the pump would not begin to pump. Then they encounter a pump that they are told is "self-priming," and they begin to question if all that caution is necessary. So, what's the real scoop on self-priming pumps?