It’s rare that rotating equipment experiences a sudden, catastrophic failure. But when it happens, the resulting analysis usually uncovers early, and often subtle, indications that equipment performance was heading downhill. Maintenance technicians I’ve worked with across many California Bay Area refineries use a variety of rotating equipment failure analysis methods—failure modes & effects analysis (FMEA), root cause analysis, the five whys, and others.
Although those general methods cover a wide range of equipment failures when the subject is a specific type of equipment, I’ve found that focusing on certain, highly-probable areas lead to a faster diagnosis. For centrifugal pumps, I recommend starting with excessive vibration, improper startup/shutdown, and seal support system issues.
Focusing on these three areas associated with rotating equipment failures will help ensure you have the right equipment for the analysis and create better maintenance practices in the future. Here’s where to start looking when assessing the reasons behind failure associated with centrifugal pumps.
A lack of planned maintenance or regular inspection of pumps, couplers, and motors leads to minor problems becoming major problems. Baseplate bolts improperly torqued during installation work their way loose. Incorrect motor and pump shaft alignment is guaranteed to induce vibration. Heavy slurries erode pump impeller vanes, resulting in a severely unbalanced impeller shaft.
Excessive vibration also undermines the integrity of a pump’s mechanical seal. Springs, O-rings, and seal faces take a beating and can no longer maintain equilibrium. Mechanical seal failure leads to leakage. And if you’re pumping hazardous liquids such as hydrocarbons, you risk violating Cal/OSHA or BAAQMD regulations.
Over time, minor vibrations have become major problems. At first, vibrations may be unnoticeable except by a technician using a vibrometer. As vibrations increase, a seasoned operator can hear the problem. But when it gets to the point where you can see the problem, it’s usually too late.
Preventing vibration begins with the proper installation of a centrifugal pump and its supporting infrastructure. Regularly-scheduled inspections should detect and correct nascent vibration problems before they worsen. Early vibration detection is one of the most cost-effective means of avoiding rotating equipment failure and the analysis required to identify and fix the source of the problem.
Even the best-planned maintenance practices can’t prevent rotating equipment failures that stem from improper pump startup and shutdown procedures. Inconsistent procedures can stress pump components and infrastructure. Procedure problems that could lead to pump failure include:
Startup and shutdown procedures vary by pump and process; there’s no single foolproof strategy. What’s the best way to avoid these problems and the rotating equipment failure analysis you’d need to do in the event of a breakdown? Start with proper training for all personnel responsible for pump operations and make sure procedural information is readily available.
Current online operations manuals linked to the pump in your enterprise asset management system should be easily accessible in print form or, even better, via intrinsically safe mobile devices. Any unique or non-standard procedures should be clearly noted. Proper training and access to up-to-date operating procedures are critical, especially when pumps are subjected to frequent startups and shutdowns where just a slight difference can jeopardize reliability.
In many industrial pumping processes, seal support systems are critical to safe and reliable pump operations. A properly operating seal support system provides fluid to the seal chamber at the right temperature, pressure, and flow. When your seal support systems aren’t working properly, you’re inviting mechanical seal failure and pump leakage. When the result is fugitive emissions, a toxic cloud, a hazardous puddle, or fire, you’re putting personnel and company reputation in Northern California at risk, all avoidable with a properly-maintained seal support system.
Although pressure, temperature, and flow are three different factors, in the table below, you’ll see that there’s a great deal of interdependence among them.
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API Plan 11 - Process Fluid Flush API Plan 75 - Condensing Leakage Collection
With a wide range of seal support systems, from a relatively simple flush using process fluid to a custom-engineered buffer gas system that condenses and collects leakage, seal support systems can be one of the more challenging aspects of rotating equipment failure analysis. In many instances, the seal support systems specialists can provide invaluable assistance with the analysis.
If you’re experiencing an increase in pump failures that are not associated with installation or operations, it’s probably time to take a closer look at those pumps and their seal support systems.
When your rotating equipment failure analysis identifies these problems, it’s time to take the next steps. First, reach out to your mechanical seal vendor who can provide the guidance you need to select and install the correct mechanical seals. Second, contact an expert seal support system vendor who will work closely with you to det ermine the right seal support system upgrades or replacements.
Swagelok’s Field Engineers and certified technicians have decades of experience working with Northern California industries, providing solutions to prevent rotating equipment failures. Being local, with facilities in Fremont and Concord, it’s easy for us to do an on-site evaluation to learn your requirements. We can help you determine whether a component upgrade best meets your needs or where replacement with a custom-configured seal support solution is your best investment.
Our assembly technicians fabricate and thoroughly test your seal support systems following ISO 9001 best practices. The result: solutions that mitigate rotating equipment failure and are backed by Swagelok’s industry-leading Lifetime Warranty.
To find out more about how Swagelok Northern California can help with failure analysis associated with centrifugal pumps by delivering solutions with expert consultation and Assembly Services, contact our team today by calling 510-933-6200.
Paul holds a B.S. in Mechanical Engineering from North Dakota State University. Before joining Swagelok Northern California, he was the West Coast Regional Sales Manager for an organization focused within the pneumatic and hydraulic industry where he supervised product distribution throughout the western United States, Canada, and Mexico. While in this role, he was able to help provide technical and application-specific expertise to customers and distribution to drive specifications.