Bearings

Latest Bearings Articles

For any bearing used in rotating machinery, applying best maintenance practices and using the correct enabling tools can help contribute to maximum bearing service life. These practices include proper storage and mounting, adequate lubrication, and close monitoring and inspection that can uncover the root causes of any damage.

Many industries use variable frequency drives (VFDs) with induction motors. Introduced in the 1960s, VFD technology has advanced considerably during the past 50 years. The engineering advancements have encouraged operators to consider other factors during particular applications, such as harmonics, energy efficiency, temperature, rise time, cable length and switching length.

Despite their simplicity, centrifugal pumps often experience repeat failures that even seasoned maintenance and reliability professionals have trouble preventing. This four-part series explains the reasons behind repeat pump failures and uses a real-world field example involving boiler feedwater pumps.

Minimizing pump downtime directly affects the bottom line. Sealless mag-drive and canned-motor pumps, commonplace in the petrochemical and power industries, enhance reliability and reduce emissions and leakage compared with more traditional “sealed” pumps. The choice between sealless and sealed pumps often involves savings in both time and money.

A multistage BB5 diffuser machine in oil transfer service in the Middle East had been in operation for many years without problems. After a routine maintenance strip down and rebuild, the pump experienced a high thrust bearing temperature of 105 C, which caused it to alarm and shut down. The temperature range had previously been 75 C to 85 C.

Within the oil and gas industry, the rotating shafts of equipment—such as pumps, motors, compressors, gearboxes and turbines—perform an essential function in both upstream and downstream applications. This rotating equipment ensures process flow and the safety of employees and the surrounding community.

Few industries can tolerate the unscheduled downtime of critical equipment. In refinery operations, it can have particularly serious implications. For an operation that runs 24 hours per day year-round, the losses—in both production and profitability—can be staggering.

Active magnetic bearing (AMB) reliability and availability levels have surpassed oil bearings after 10 years of technological advancements. These advances have made an impact on the industry, drawing attention from major original equipment manufacturers globally.

Bearing currents occur in specific motor and drive installations and can lead to motor fatigue and failure. While no system is inherently immune to bearing currents, few installations experience bearing currents during normal operation. While many installations have preventive measures installed, knowing that protection is in place is sometimes outside the owner or operator’s scope.

Misalignment is a frequent cause of rolling bearing failure. It can cause cage fracture, which will result in seizure of the bearing, pump failure and costly downtime. It can also cause edge loading, which will result in early bearing failure.

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Columns

For those of you old enough to remember Lawrence Welk, you’ll notice that the title of this brief column is the final quote from his show’s closing song. I am still a loyal fan of his reruns today.

Last year, “Reduce Thrust and Extend Bearing Life” (Pumps & Systems, December 2013) discussed the benefits and some potential pitfalls of adjusting the axial clearance of American National Standards Ins

A reciprocating power pump, as depicted in Figure 1, is a displacement machine. It has characteristics that are different than a centrifugal pump.

Blogs

Abundant oil supplies from U.S. shale producers may have upset global markets in recent months, but one resource may present even more of a challenge to the international community in 2015—clean water. Demand has clearly outstripped supply in some of the world’s most arid regions.

My previous two columns have described assessing a system that does not use controls. In the first part (Pumps & Systems, October 2014) the assessment process was detailed. Last month, I covered performing the system calculations (Pumps & Systems, November 2014).

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