Tag Archives: vibration

Hydro Centaur Pipeline Deployment

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Hydro’s Centaur recently deployed a new installation across a pipeline in the Midwest US, demonstrating the continuing growth of demand for smart condition monitoring solutions.

The pipeline end user chose Centaur over other options under consideration because Hydro has the subject matter expertise behind the equipment being monitored. This distinction allows Hydro to not only be a monitoring partner, but to be a partner in reliability across the equipment life cycle.

With Centaur’s real-time data, the end user is able to proactively service their equipment and identify incipient issues before they develop into greater problems. Through a collaboration between the pipeline team and Hydro Centaur’s dedicated monitoring engineers, any problems that are identified will receive a comprehensive root cause analysis and proposed modifications will be developed to prevent problem reoccurrence. These solutions can be implemented through Hydro’s extensive global service network and, if necessary, tested in a controlled environment in Hydro’s Performance Test Lab.

We are proud to support our customers with services and solutions that drive measurable results.

Reliability Enhancement for Circulating Water Pump

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A large Midwestern coal-fired power plant had been experiencing vibration issues and premature failures with their large Kirloskar 130 BHM circulating water pumps. The plant has two operating units, with three circulating water pumps installed in each unit. The average life of the equipment was 6 months, which is far belong the industry standard for a large vertical turbine pump in this service. The pumps were sent to Hydro’s HydroAire 40th Street service center for a causal analysis and remediation of any problems that were found during the investigation.

 Upon disassembly, it became apparent that there were several critical issues that needed to be addressed to increase the reliability and mean-time-between-repairs for this equipment. The discharge head gussets were heavily eroded clear cracks and dislocation, which weakened the discharge head assembly and made is susceptible to high vibration.

The stuffing box was also eroded, which would make it difficult to successfully perform pump-to-motor alignment in the field upon reassembly at the site.

Another area that added to the high vibration was excessive bearing clearances. The guide bearings and shaft sleeves exhibited excessive wear, which would have reduced the stiffness and damping of the rotor assembly. Several factors were likely contributors to the bearing wear.

Fit-ups of the stationary assembly were excessive with average fit-ups measuring in the range of 0.010 – 0.030”; for reference, Hydro’s typical acceptance criteria are 0.001 – 0.003”. Critical faces and bores were also found out of acceptable tolerance, with concentricity, parallelism, and perpendicularity measuring in the range of 0.005 – 0.015”, where acceptance is usually held less than 0.002”. Not only did the out of tolerance fits contribute to overall misalignment, they provided a leak path that resulted in erosion of the column pipes at the fit areas.

 

Excessive wear was also found on the impeller vanes and the impeller liner surface, indicating contact between these two components. This contact was likely caused by both the overly loose impeller fit and non-concentricity of the rotor and stator, as mentioned above. The impeller vane wear would have increased rotor imbalance, further increasing vibration. The opening of this clearance would have also reduced the pump efficiency, causing it to lose performance and require more energy to operate.

In addition to the factors that likely caused misalignment and contact between the stator and rotor was that the fluid being pumped had a high sand content, which made it an especially harsh environment for the bearings and sleeves. The shaft sleeves were found to be a hardness of only 32Rc, which was insufficiently hard to resist wear. The shafts themselves also exhibited wear at the sleeve location, which increased the overall cost of maintenance for this equipment. The guide bearings were self-lubricating soft bearings made from a composite material and did not have any fluting to allow particulate in the fluid to pass more easily through the tight clearance without wear and were deemed inappropriate for this application.

Modifications were designed to provide structural reinforcement to the discharge head and to eliminate the factors causing premature wear of the bearings and shaft sleeves. The eroded gussets were removed and replaced with thicker, more robust gusset to enhance the structural integrity of the components. The new gussets and lifting lugs were fabricated from carbon steel and installed using precision welding. A PT inspection was completed to ensure weld integrity. The eroded stuffing box was also repaired using weld restoration techniques.

To improve the alignment of all components within the stationary assembly, any out of tolerance fits and bores were welded up and machined to best-in-class tolerances and fits.

Vertical pumps are especially susceptible to misalignment since they have a large number of stacked components. Large fit-ups between each component can easily stack-up to a large offset at the bottom of the assembly that exceeds the bearing clearance. By restoring recommended fits and tolerances, non-centerline compatibility between the stationary and rotating elements would be greatly decreased.

The impeller was laser scanned to create a solid model of the component that could be used to establish the correct vane profile of the component before it had been worn. This model was used to create the vane profile machining drawing that was used during impeller refurbishment. The solid model was also used post-machining to confirm that the machined component conformed to the expected dimensions during as-built inspection. The impeller bore was also corrected to provide the appropriate fit-up to the shaft.

To add additional wear resistance, the shaft sleeves were upgraded to 410 stainless steel and provided with direct laser deposition (DLD) cladding on the running surface to enhance durability and wear resistance. The shafts were chrome plated at the fit locations to extend their service life as well. The bearings were upgraded to a cutlass rubber design that included axial grooving to improve longevity and overall pump performance.

The impact of these enhancements was clear upon reinstallation of the pump at the power plant. The modifications significantly improved the pump’s structural integrity, alignment precision, and wear resistance. By implementing these targeted upgrades and providing a quality repair, Hydro was able to ensure that the end user would achieve reliable performance in demanding operating conditions. The reinstalled pumps have now been operating for more than 3 years, which is already 6 times the life they had previously been experiencing. The high vibration was eliminated and vibration is now measuring below any alert or alarm levels.

Interested in learning more about our HydroAire 40th Street facility? Meet them here.

You can also explore our experience with large vertical pumps here.

Wednesday Webinar: Vibration Concepts

Join us for March’s webinar, where instructor Glen Powell will introduce concepts and terminology related to vibration, including frequency, amplitude, phase, vibration waveforms and spectrums, vibration equipment, machinery faults, and resonance.

Register

Blower Outboard Bearing Failure Identified through Advanced Condition Monitoring

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Introduction:

Maintaining the reliability and efficiency of critical equipment is paramount. This case study highlights the value of continuous, real-time condition monitoring by describing the how a premature failure was identified and resolved in a blower unit installed at a specialty materials manufacturer. The proactive implementation of Hydro’s Centaur condition monitoring played a pivotal role in early detection, enabling swift intervention and preventing unnecessary downtime.

Background:

A large US chemical plant that creates a variety of specialty materials had ongoing troubles with the centrifugal blowers in their PVC division. The units are critical to production and do not have spare backup units. Hydro’s Centaur condition monitoring solution was deployed on these blowers to understand the nature of the failures as well provide insight into when the units needed attention. One of the blower units began exhibiting concerning signs on January 04, 2024. Vibration levels steadily increased over the subsequent weeks, reaching a critical point on February 9th, 2024. This prompted the decision to shut down the unit and perform a root cause analysis to quickly determine remedial actions and keep production downtime to a minimum.

Events and Details:

When elevated vibration amplitudes were first detected on the problematic blower, they were in the Blower Outboard Bearing in the vertical direction (BOBV). The velocity amplitude shown below crossed the warning threshold on January 06, 2024, alerting both Hydro and the end user’s site engineers that a condition was present and in blower was in the early stages of degradation. The observation was discussed during the weekly touchpoint between Hydro and the plant, where Hydro would review the health of all monitored assets and address any alarm events captured using Centaur with site stakeholders.

Figure 1: Velocity Amplitude as Several Alarm Thresholds Breached

The vibration velocity amplitudes continued to climb, and on January 25, 2024 they crossed the Alarm #1 threshold. The Alarm #2 threshold was breached on February 01, 2024. Continual touchpoint meetings highlighted the worsening conditions and provided an analysis of the suspected failure mode(s) affecting the blower mechanical condition. The below multi-spectrum chart shows the spectra at the BOBV location at various points along the trend – mapping the signature of the degradation.

Figure 2: Multi-Spectrum Chart of BOBV Location

The chart starts with the spectra during “normal” conditions, prior to the observed degradation. Peaks at 1X and several harmonics are present with an amplitude less than 0.15 ips RMS. As the problem is observed and continues to worsen, bearing fault frequencies and harmonic excitation appear and continue to get worse. The lowest spectrum in the chart shows vibration velocity amplitude during the final sample, when it is greater than 1 ips RMS – very severe. At this point, all the energy has moved to 1X or less than 1X frequencies – a common occurrence when a failure mode is in its final stages.

The following two spectra charts take a closer look at the condition, one chart showing the initial conditions prior to degradation and the other closer to the end of operation where bearing fault frequencies and harmonic excitation can be detected.

Figure 3: Initial Conditions

Figure 4: Near End of Operation

In parallel with the velocity measurement, Hydro and the plant reliability engineers reviewed the acceleration measurements at the same location. Acceleration often leads to velocity readings, particularly for bearing failure. The chart below shows the trend for acceleration with the amplitude shown in g’s.

Figure 5: Acceleration Trend

The following four charts show the spectra and waveform data for acceleration readings at two points during the degradation period. The first two charts show the early stages of failure with peak-to-peak amplitudes of ~6 g’s and harmonic excitation in the spectrum. The second two show acceleration data at a later stage of degradation with peak-to-peak amplitudes at ~30 g’s and increased discrete frequency amplitudes in the spectrum.

Figure 6: Waveform- Early Stage of Failure

Figure 7: Spectrum- Early Stages of Failure

Figure 8: Waveform- Late Stages of Degradation

Figure 9: Spectrum- Late Stages of Degradation

The observation noted throughout was that the blower outboard bearing was failing. Failure of this bearing could also translate to damage to the shaft and other blower components if not addressed in a timely manner.

Constant communication between Hydro and the plant prevented the issue from becoming an unexpected and catastrophic failure.

Root Cause Analysis & Remediation:

The data captured by Centaur during the monitoring period was instrumental in conducting a thorough root cause analysis. It provided a comprehensive overview of the conditions leading to the outboard bearing failure, enabling Hydro’s engineers to identify contributing factors, such as operating conditions, lubrication issues, resonance frequencies, and potential misalignments.

The root cause of the issue was found to be contamination. This PVC unit created a fine dust byproduct that was found in the atmosphere, with large quantities accumulating around the blower units. Over time, the fine PVC dust would penetrate the bearings, compromising the effectiveness of the lubrication and reducing the tolerance inside of the bearings. Plans for remediation included relocating the machines or redesigning the bearing and housing to eliminate the possibility of contamination. The plant ultimately decided relocation was not an option and consulted the bearing manufacturer for an improved design that included a sealed housing.

Hydro continues to monitor these units, with ongoing reviews of the oil quality, level, and possibility of contamination from moisture, metal, or other sources. In parallel, Hydro also recommended reviewing the load handled by this blower and the rated load of the specified bearings, as improper loading may contribute to premature bearing failure.

Results: Cutting Edge Tech and Real-Time Support

Centaur proved to be the first line of defense in identifying abnormalities in the blower unit’s performance. Leveraging real-time data analytics, Centaur detected escalating vibration levels and issued timely alerts based on preset alarm thresholds. This early warning system allowed the maintenance team to take proactive measures, and consult with Hydro’s engineers on the data, receiving immediate real-time support thus preventing a catastrophic failure and minimizing the impact on overall operations. The ability to pinpoint the issue before complete failure occurred significantly reduced the downtime and associated costs.

This case underscores the value of proactive maintenance strategies for rotating equipment. With a strong focus on customer needs, experience across brands and applications, and a commitment to innovation, Hydro’s capabilities and culture uniquely aligned with the customer’s goals for improving asset reliability and performance.

Learn more about Centaur and how it can help you reduce the cost of rotating equipment ownership.