New bearing system keeps circulating water pumps running in a
nuclear power plant.
Magnetic bearing systems represent a different approach from rolling bearings to support rotating machinery, and in recent years, their benefits have attracted attention for more applications.
When a component of a large circulating water pump fails in a power plant, the power plant must often spend hundreds of thousands of dollars to remove the pump from service, replace the failed component, rebuild the pump and return it to service. In addition, circulating water pumps can require work on a massive scale-they can measure 30 ft or more in length and pump an average of 165,000 gpm. Rotating shafts for these pumps can measure 8 to 10 in. in diameter.
In December 2008, we discussed some reasons ball bearings run hot. In December 2006 (ref. [1]), we described the common pitfalls of incorrectly dimensioning shafts during repairs. This time, we will examine the cousin of a ball bearing-a roller bearing-and some of the pitfalls that occasionally cause hot operation.
Given time, every component of the rotating machinery will eventually fail, even when operating in a perfect environment. For instance, rotation of the shaft subjects it to alternating load, changing from tension to compression with each shaft revolution.
Knowing the basics of pump repair can simplify preventive maintenance.
Frequently, guide bearings are incorrectly blamed for a problem that has nothing to do with the bearings. Unless the bearings have a material defect (which would be unusual), guide bearings do not cause pump problems. Rather, guide bearing failures are the result of other problems that the pump is experiencing.
Pump manufacturers in a variety of industries are increasingly asked to deliver more with less; they need to handle increased loads with improved system efficiency but reduce envelope, environmental impact and total system cost.
What is the secret to continuously baking or processing cakes, pizza, chicken, beer and thousands of other foods and beverages? Mechanical carbon materials used in the food processing equipment produce these foods safely and cost effectively.
Magnetic bearings have the advantage of non-contacting, super-low friction performance. With no liquid lubricant needed, they are increasingly being used in applications involving vacuum operations, refrigeration, semiconductor production, biotech and pharmaceutical operations. All these are applications in which cleanliness is key and contamination from lubricants is intolerable.
It has been 54 years since Tracy Hall invented the first manmade diamond at the General Electric (GE) laboratories in Schenectady, New York. Since then, synthetic polycrystalline diamond (PCD) has found wide use as an abrasive and as a cutting element, with an annual market of $4 billion (3 billion carats in 2005).
Q. Our pumps take their suction from an open tank. When the liquid level drops, surface vortices are formed that allow air to be drawn into the pumps. What changes can be made to the tank to correct this problem?
Babbitt bearings, frequently found in large steam turbines and generators in major power plants, can provide years of service if properly maintained. By using state-of-the-art technology and repair practices, aftermarket suppliers who specialize in Babbitt bearings can repair equipment and increase the life of Babbitt bearings.
Lubricants for rotating machinery primarily serve to separate rolling and sliding contact surfaces, protect highly finished bearing surfaces from corrosion, protect against contaminants (in the case of grease) and serve as a heat-transfer medium (in the case of oil). An effective lubricant management program-grounded in proper lubricant monitoring and analysis practices-can help reinforce these functions and, in the process, deliver vital information about the machinery's condition and health.
Rolling bearings are precision machine elements found in a wide variety of applications. They are typically reliable even under the toughest conditions. Under normal operating conditions, bearings have a substantial service life, which is expressed as either a period of time or as the total number of rotations before the rolling elements or inner and outer ring fatigue or fail.
Bearings perform vital roles in enabling optimized operation and service life of pumps used throughout industry. In centrifugal pump applications, for example, crucial functions abound.
For more than 100 years, machine parts composed of mechanical carbon have provided an alternative solution in applications where temperature and atmosphere prevent the use of oil-grease lubricants. Mechanical carbon materials contain graphite, which is relied on for its self-lubricating characteristics.
The pump is a 300-hp integrally geared propylene product pump in a Gulf Coast olefins unit that operates at 25,000-rpm and produces 6000-ft of head (see Figures 1 and 2). The suction and discharge pressures of the pump are 250-psig and 1500-psig, respectively.
Rolling bearings play vital roles as the hearts of rotating machinery (pumps included) by supporting shafts, locating loads, enabling rotation and reducing friction. When bearings need to be replaced, improper dismounting and mounting techniques can shorten their life expectancy.
Maintenance and repair functions constitute a significant component of pumping system life cycle costs, especially in terms of energy consumption. The proper selection and lubrication of bearings can help bring economies and efficiencies into line.
The initial cost of a pump is a small component of the pump's total life cycle cost. Progressive, proactive maintenance practices are vital to maximize pump life, minimize downtime and avoid costly repairs and lost production.
Rolling element bearings are mechanically complex compared to plain bearings, but are indispensable in a large variety of functions.
Currents are induced on the motor shafts when AC motors are employed with VFDs to drive air pumps, chillwater pumps and compressors in HVAC/R systems. Without a grounding device, these currents typically discharge through the motor bearings, causing frosting, pitting, fusion craters, and fluting.
An unexpected bearing failure needs to be understood and seen as an opportunity for improvements.
How to determine the root cause of bearing failure by analyzing telltale signs.
In this age of environmental consciousness, OEMs around the world are competing to build better, safer and greener machines. In striving toward such lofty goals, many industries are rediscovering a fundamental principle-magnetics.
Explore some of the issues associated with vertical pump bearings in general, and nonmetallic bearings specifically. Nonmetallic bearings may not be the best answer in every case but have been an excellent choice for many applications worldwide. In general, these product-lubricated bearings preclude additional contaminants (oils, greases) infiltrating the pumped fluid.
For more than 25 years Shock Pulse has proven to be a valuable method for evaluating bearing condition. Shock Pulse is easy to use and understand. With the addition of enveloping to the Shock Pulse signal, a more exact diagnosis is available, allowing end users to identify the damaged component within the bearing.
