Case Studies

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.

State of the Art Parts- Rerated Impeller

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Hydro Parts Solutions recently manufactured three impellers for a rerate project being developed through Hydro’s Rocky Mountain service center in Denver, CO. Hydro Global Engineering determined the new hydraulic design for the rerated pump, which required modifications to the casing and new impellers.

 

The end user chose to have the new impellers manufactured out of CA6NM using investment casting, which provides a smoother surface finish to slightly increase the impeller efficiency. Hydro Parts Solutions drove the project from casting package design through final machining, with the impellers being cast and finish-machined within 6 weeks.

The new pump design was successfully tested at Hydro’s performance test lab, validating the new hydraulics. The custom performance will help the midstream end user achieve their desired system flow with maximum reliability and minimum energy usage.

Explore Hydro Parts Solutions’ design process in this video case study.

Hydraulic Rerate Proven in Performance Test Lab

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Custom Hydraulics for the Midstream Market

This summer, Hydro completed a hydraulic rerate project for a major US midstream pipeline. The project was completed through Hydro South, Hydro’s southeastern US service center in Alpharetta, Georgia. The project was completed with testing support from the Hydro Performance Test Lab, Hydro’s 5000 HP test facility located in Chicago, IL, with engineering direction from Hydro Global Engineering, based in Manchester, UK.

The pipeline originally used two booster pumps and the use of a Drag Reducing Agent (DRA) to achieve the desired flow rate. To increase the overall flow capacity of the line and remove the need for the DRA, the end user specified a pump to be added to the system downstream of the booster pumps.

The pump performance specifications were developed by system engineers and communicated to Hydro. The pump’s original design condition was modified to provide the necessary differential pressure required for the desired flow rate – for today and in the future. This will be achieved without the use of DRA or with little added to the system.

Hydro modified an existing pump casing provided by the pipeline and designed new impellers to meet the specific hydraulic performance requirements. Using computational fluid dynamics and advanced modeling, the new impellers were manufactured and installed by Hydro, then sent to Hydro’s test facility for hydraulic performance testing.

To provide an exact performance match, a larger impeller diameter size was selected for the first test and subsequently trimmed to meet performance within API 610 tolerances. Along with the hydraulic performance test, the mechanical integrity of the pump was measured with a vibration test, mechanical resonance test, and a bearing housing temperature stabilization test. All this information validates the quality of the rebuild and ensures a reliable machine.

The pipeline has a limited ‘budget’ of DRA concentration allowed pipeline wide. This concentration is measured in part per million (ppm). By adding the hydraulically rerated pump to the branch line, the DRA ppm budget can be allocated elsewhere in the pipeline. This will add efficiency and increase overall throughput.

Hydro is very fortunate to support critical industries like midstream pipelines in ensuring safe, reliable, and cost-effective pumps and rotating equipment.

Learn more about Hydro’s Performance Test Lab and Engineering Services