Tag Archives: case study

Innovative Vertical Pump Sealing Solutions

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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

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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.

Headbox Feed Casing Refurbishment

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Application: Headbox Feed
Pump Details: Single-stage Sulzer ZPP 800
Pump Type: Double-suction Horizontal Split Case

After years of useful service, casings of many horizontal split case pumps are quite worn and no longer meet the original specifications. Hydro offers an alternative to purchasing a new OEM casing that offers a much lower cost and reduced turnaround time.

Due to their long-standing relationship with Hydro, a paper mill decided it was time to restore the casing of their headbox feed pump. Because this pump was in a critical application, the mill required a very short turnaround time.

To avoid a temporary shut down of the mill, Hydro was able to perform a line bore and insert upgrade within a period of three days. Utilizing around-the-clock shifts, Hydro completed the case inspection and developed machining fits and tolerances to restore the casing to its original specifications. Hydro then manufactured and mounted inserts to the casing.

Not only were the casing and wear components restored to their original fits, the upgraded materials will significantly improve mean-time-between-repair.

Learn more about Hydro’s targeted upgrades for the pulp and paper industry here.

Casing Geometry

Fertilizer Focus: Expedited Sourcing for Replacement Casing

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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.

 

a man wearing a blue hat

Centaur Condition Monitoring Early Detection Saves Over $200,000

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As part of Hydro’s support of a Midwest steel mill’s descaling pumps, the Centaur condition monitoring service has been installed on five of their pumps machine trains. Using wireless sensors, Hydro has been continuously collecting real-time vibration and surface temperature levels on the pump, gearbox, and motor. The goal of this monitoring service is to work directly with the end-user to improve rotating equipment maintenance strategies through better, more frequent data collection and Hydro’s subject matter expertise in rotating equipment.

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