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This Guide is an introduction to rotating equipment construction, operating principles, troubleshooting, and best practices.
Contents of this Guide
Rotating machines power our production facilities by safely transporting a wide variety of liquids, gases, and solids. Those of you who have worked in a production site for any length of time know that not all process machines are created equal. Some are more critical than others; some are small and some are very large; some spin fast and some turn very slowly. The great diversity in their construction and application can be daunting to a new operator and a challenge to the veteran.
When process machines fail catastrophically, bad things happen. These bad things are called consequences; but not all consequences are equal. For example, if a critical machine fails, the consequence can be the stoppage of an entire process or even an entire process facility, which may have a significant cost related to the outage if it is lengthy. Another consequence associated with machinery failure is the release of a dangerous process fluid if its seal fails. A final example is the cost of a major machine failure. If an internal mechanical failure is not detected early, more and more secondary damage will be incurred, eventually resulting in a hefty repair bill. Catastrophic failure can cause serious safety and environmental issues as well.
Figure A (below) depicts how machines tend to fail. On the left, a machine is operating at an optimal, or 100% condition; pressure, flows, and temperatures are normal throughout the machine. Then maybe a bearing begins to fail or an impeller fouls causing vibration. For whatever reason, the machine's condition begins to degrade. As the problem continues, we may begin to experience vibration and later to hear noise. If the machine is allowed to degrade further, we will start to sense heat and then see smoke. Finally, if we continue to keep running this ill-fated machine, it will fail catastrophically and stop suddenly. Dire consequences, such as a product release or fire, could also occur.
This is no way to run a production facility! The goal of every operator should be to detect machine failures or degrading machine support systems as early as possible. Early detection of unwanted machine conditions, which is the central theme of this guide, is the safest and most cost effective philosophy to employ. Identifying a problem before major damage occurs allows more time to plan the required repair or adjustments in order to minimize downtime and repair costs. An operator trained to identify degrading machine conditions before serious damage can occur is worth his or her weight in gold.
We all know that operating personnel are constantly being bombarded with more regulations, increasing training requirements, incessant paperwork, and that the number of operators per machine is dropping every day. This means the number of "eyes" available to watch critical equipment is constantly diminishing. But this is not a hopeless situation. This challenge to do more with less is driving production organizations to find more and more efficient ways of conducting business so that profits do not come at the expense of safety and the environment.
One such way to improve operational efficiency with little or no additional cost is to infuse an equipment reliability attitude into the organization from the ground up. Operators are the backbone of this reliability effort. Without committed, well trained operators reliability programs, no matter how well designed, are doomed to failure. To reap the full benefits of an equipment reliability program each and every operator must endeavor to:
• Gather data for troubleshooting and potential root cause failure analysis
• Identify symptoms of potentially damaging machine distress that can be rectified through adjustments, such as alignment, lubrication, balance, and changes in operating conditions
• Identify machine failures in their early stages so that secondary damage is avoided and ample time is available to plan proper repairs
• Maximize rotating equipment reliability by continuously striving to lessen the time between machine repairs
• Strive to operate machinery reliably and efficiently with the benefit of cost control for the owner.
• Protect life and limb
• Protect the environment
All site managers will agree that profit is meaningless if it comes at the cost of an injury or an environmental incident. It is prudent for an operator representative to be included in all capital work for input of a practical nature i.e. valve heights, orientation, and operability of equipment. Operators who give truthful and significant information on equipment and processes must not be disciplined for doing so. To do so would eliminate significant data and information in the future.
Working around process machinery equipment for a long time one can become accustomed to having it work as it should. Some machinery can even become "invisible" if it is out of sight or very reliable.
It is easy to become oblivious to potential problems, especially if they develop gradually. The simple techniques of touching, listening, and visually inspecting machinery while on rounds or even just passing by will ensure the best possible life for machines and drive costs down by catching problems early before they develop into costly failures.
The key to detecting problems early is to know what "normal" is. The operator is in the ideal position to know how a piece of equipment is supposed to sound, what pressures are normally produced, and what the equipment feels like when it is doing its job.
The goal of this guide is to present proven techniques that will enable rookie and veteran operators alike to detect problems early, eliminate major outages and control maintenance costs. To achieve this goal we will explain the basics of lubrication systems, bearings, drivers, seals and sealing systems for centrifugal and positive displacement pumps as well as turbines, centrifugal compressors and reciprocating compressors. We will then present common sense inspection methods for centrifugal and positive displacement pumps, gear boxes, motors, heat exchangers, and turbines.
After you feel you have mastered the first four SECTIONS, you can move on to more advanced material found in the last three SECTIONS which include:
"An Introduction to Compressor Operations",
"Lubrication Advice for Operators", and "More Machinery Best Practices".