Modifying Existing Equipment to Maintain Operational Standards

Many aging manufacturing facilities have witnessed changes in market demand that have altered their product slate and capacity. These changing system demands often cause equipment that was previously well-sized for the application to run significantly away from the operating range where peak efficiency and reliability are achieved. Running in this mode drives up the life cycle cost of equipment due to short maintenance cycles and wasted energy. In cases where reliability is severely compromised, equipment operating costs can also be accompanied by risk to production due to mid-cycle failures and unavailability of equipment.

To maintain safe, reliable and cost-effective operation, it is important to ensure pump systems are optimized. When approached with the need to optimize a pump system, many end users will look to purchase new equipment for the changed demand. This can be a costly and time-intensive endeavor, as new equipment installation is often accompanied by baseplate and piping modifications that require the system to be taken offline. In contrast, modifying the existing equipment to meet the new system needs provides a custom solution that maintains the original footprint, can be completed on a more aggressive timeline and often provides a more custom fit to the system.

The decision to perform one such modification was made by a major Gulf Coast oil refinery that was running at a significantly lower flow than the original system demand. The site reliability team worked with Hydro to design and implement an extreme downrating of the existing equipment. The result was an optimized system that improved reliability of not only the pump, but other affected system components. 

Read our latest case study published with Pumps & Systems magazine where Hydro’s Sergio Ramos outlines how the process for this downrate and what the final outcome was for the end user.

Learn more about Hydro’s engineering services.

Blower Outboard Bearing Failure Identified through Advanced Condition Monitoring

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.

Innovative Vertical Pump Sealing Solutions

Upgrade in Action: HydroSeal 

Vertical pumps have reliability and maintenance considerations unique to their design and application. One of these considerations is the pump seal design. Many vertical pumps rely on packing in lieu of mechanical seals. While it is a less sophisticated design, packing has benefits for vertical pumps, including greater ability to handle fluid with particulates, less sensitivity to misalignment, and greater stiffness and damping provided at the seal location. However, packing also has multiple disadvantages, foremost of which is the need to continuously adjust the packing gland to maintain the desired leakage rate and the requirement that some fluid must leak to the atmosphere. The cost associated with replacing worn components in the packing area is another notable drawback.

 

In cases where any of the disadvantages associated with packing or a mechanical seal noticeably impact reliability or the cost of operation, upgrading to a seal casing design is an attractive alternative. This is the decision that a pulp and paper mill in the Southeastern US made when experiencing reliability and environmental concerns in their River Water pump system. Faced with the need to install a new sealing device, they decided that the ability to avoid aboveground leakage and eliminate time-consuming periodic maintenance justified the investment in a vertical pump seal casing.

Read the full case study in World Pumps March/April 2024 edition.

Learn more about Hydro’s Hydro South service center and Hydro’s Engineering Services.

Navigating Resonance Challenges

A Case Study in Diagnostic Testing and Innovative Solutions

Some services are inherently difficult due to factors such as fluid quality or multiple disparate operating points.  These factors are an inherent part of the process and cannot be changed to improve reliability. Harsh applications can be a costly prospect, both in overhaul costs and in the time and labor required for frequent servicing. Many times we become caught in the perception that there is no improvement to be had for these services. A short mean-time-between-failures (MTBF) becomes routine and expected, and maintenance activities and parts procurement are built around this expectation.  

When equipment is sent out for refurbishment, the expectation is that mechanical and hydraulic performance upon reinstallation will be better than what was experienced in the worn condition. This assumption holds true in most cases; however, sometimes unexpected behavior can occur after a pump is remanufactured and reinstalled. While it is easy to jump to the conclusion that these performance changes were caused by errors made during the repair or installation of the equipment, sometimes the problem is more complex and related to latent weaknesses in the design that had lain dormant until refurbishment.

This scenario was experienced by a power utility in the Southeastern US when they ran into significant vibration increases after one of their boiler feed pumps was refurbished by a local repair shop. Concerned by the level of vibration, the utility reached out to Hydro South, who have extensive experience in this application and model. From there, Hydro Reliability Services was called on to collect data on the problematic equipment and use advanced modeling tools to understand the nature of the vibration. The field testing and analysis revealed that pump had been operating with a very small margin between a structural resonance and one of the pump forcing frequencies. Armed with this information, solutions were developed to increase this margin and return to stable operation.

Read the full case study in Pumps & Systems March 2024 edition.

Learn more about Hydro Reliability Services and how they support field testing, vibration troubleshooting, and advanced system studies.

Casing Geometry

Fertilizer Focus: Expedited Sourcing for Replacement Casing

A Midwest US fertilizer plant had a boiler feed pump whose casing suffered from significant erosion damage at the packing gland location. The damage to the casing was severe enough that it was unusable. The delivery time and cost for a new pump both exceeded what the plant felt comfortable with, so they looked for alternative means to return the pump to reliable operation.

To provide a solution that reduced cost and lead time, Hydro’s Chicago service center explored various outlets for a used casing that could be refurbished for the service. Fortunately, a casing that matched the original boiler feed pump’s size and number of stages was found and procured.

Understanding the importance of casing geometry for hydraulic and mechanical performance, Hydro’s engineering team performed an extensive analysis of the two cases to verify geometric equivalency. After the engineering analysis concluded that the used case would meet the required hydraulic performance, it was refurbished and brought up to best-in-class tolerances.

Boiler feed pump casing

As a final check to ensure that the refurbished case would operate smoothly and achieve the desired performance, the newly assembled pump was tested at Hydro’s performance test lab. The test lab generated a full performance curve that verified that the pump met the design operating flow and head. Mechanical performance was also assessed to ensure that vibration was acceptable throughout the operating range.

By reusing an old casing instead of purchasing a new pump, the site was able to reduce the cost of the repair. More importantly, the repair was completed in a much shorter timeframe than it would have taken to source a new pump. This greatly reduced the risk to plant production of not having a spare pump available on-site.