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.
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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.
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.
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.
Rolling element bearings are mechanically complex compared to plain bearings, but are indispensable in a large variety of functions.
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.
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.
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.
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.
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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.
An unexpected bearing failure needs to be understood and seen as an opportunity for improvements.
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).
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.
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.
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.
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.
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.
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.
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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."
