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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.
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.
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.
The benefits of predictive maintenance are becoming readily accepted throughout industry in Europe as well as North America. Guy Mertens, who is responsible for predictive maintenance at the Belgian Refinery Corporation (BRC), added an extra dimension to his predictive maintenance program by using it to identify common machine faults for the maintenance staff to watch for.
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.
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.
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.
Progressive maintenance practices are vital to maximize pump life, minimize downtime and avoid costly repairs and lost production. It is good practice to plan the detailed groundwork of maintenance programs, along with contingencies for various maintenance events to minimize downtime.
Latest Bearings Articles
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.
When evaluating bearing distress, the babbitted shoe surface is commonly the only area that is examined. Although a great deal of information can be extracted from the babbitt appearance, additional information exists elsewhere.
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.
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.
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.
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.
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.
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.
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.
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.
Columns and Blogs
In this multi-part series, we will investigate several aspects of centrifugal pump efficiency.
First of Five Parts
Since the original publication of this draft standard in the January 2008 issue of Pumps & Systems, I have received feedback, encouragement, numerous questions and criticism. The draft listed three basic levels of repair.
The McGraw-Hill scientific dictionary [5] states that a volute is "a spiral casing for a centrifugal pump... designed so that speed will be converted to pressure."
