Maximizing Efficiency in Descaling Pumps

descale pump impeller damage

A showcase of severe corrosion with one of the descale pumps’ impellers.

A major steel plant on the East Coast had been experiencing catastrophic failures with maximizing efficiency in their five- stage descaling pumps for more than four years.

The plant operated using three multistage axially split (BB3) pumps with two spares. All five of the pumps had a mean time between repair (MTBR) of two years.

The water quality at the plant was considered to be less than ideal. The entrained abrasives were also a factor contributing to the repeated failures.

The client reached out to both the OEM and several aftermarket repair shops for over the past five years with hopes for a more permanent solution.

A global aftermarket pump service provider repaired one pump several years ago. It had provided the longest run time, operating more than four years without failure.

Read the full article at pumpsandsystems.com

Optimizing Reliability Through Material Upgrades

At a combined cycle power plant, a boiler feedwater pump was experiencing problems. Dr. Gary Dyson of Hydro, Inc. and Larry White of HydroTex discuss how major cost savings were provided through engineering analysis, material upgrades and testing for validation.

A combined cycle power plant in the Pan Handle region of Texas found themselves experiencing repeated failure on one of their 14 stage boiler feedwater (BB3) pumps. The pump had recently been modified by the supplier to provide a short-term solution. This in turn reduced the mean time between failure (MTBF) of the pump, requiring continued support and further analysis.

Combined cycle plants are comprised of both gas and steam power production technologies, capable of producing up to 50% more electricity than traditional simple-cycle plants. With the ever-increasing demand for energy, this technology is becoming increasingly relevant in throughout the pump industry. As such, it is highly important that these plants operate at peak efficiency.

Originally, the stationary inserts at several locations in the pump assembly were modified in such a way that increased the likelihood of friction and galling of the stationary and rotating parts of the pump assembly. The consecutive failures experienced on site were repeatedly of the same failure mode, which strongly points toward a pump design problem.

Read the full article at worldpumps.com

Finding flaws with Forensic Analysis

A fertilizer plant in the Gulf of Mexico experienced a suction cavity high pressure ceiling leakage in one of their BB5 boiler feed pumps. By utilizing a forensic analysis, Hydro discovered a simple shortcut in the manufacturing process was costing thousands of dollars in repairs and great inconvenience.

Written by: Pete Erickson and  Todd Soignet
Published by: World Pumps

A BB5 barrel pump at a fertilizer plant along the Gulf of Mexico experienced reduced capacity due to suction cavity high pressure sealing leakage. This was not the first time their boiler feed pumps had experienced a loss of capacity. The pumps were only about a year and a half old and were part of a major expansion project at the plant.

Due to high lead times, the plant decided not to continue repairs, but instead do a simple swap out, when a Hydro service center was recommended by the client’s sister plant as a credible supplier who had the technical and engineering expertise needed to rebuild pumps to the highest quality standards.

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Beware the Cheap Fix: You May Get What You Pay For

Fossil plant required an emergency rebuild when poor quality repair caused a holiday shutdown. 

Written by: Dr. Gary Dyson & Mohamed Mohamed
Published by: Pumps & Systems

The consequences of poor quality repairs can result in premature failure, unplanned outages and higher repair costs because follow up after the initial attempt is considered an emergency repair. That was the situation when a major fossil plant experienced an emergency failure of a six-stage, boiler feed pump element. It was a quiet holiday night when the pump had to be pulled due to lack of flow, causing a plant shutdown. Unfortunately, when the plant tried to set the spare element up on bearings, employees were unable to turn the rotor. In this case, the emergency occurred when the repaired spare element had to be used immediately after initial failure. Thus, the problems with the previous repairs were uncovered.

Because it was the holiday season, the plant’s usual service provider could not respond in the required time. Another Hydro was called in to assess the problem, engineer a solution and save the plant thousands of dollars in downtime.

Field service was mobilized to provide labor in two 24-hour shifts.

Worthington element

Image 1. Worthington element set on precision v-blocks, checking vertical and horizontal clearances at the suction end and discharge end. These checks are used to see if element is concentric.

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Seal replacement reveals causes of excessive vibration

During a mechanical seal replacement of a major gas plant, a reliability engineer identified that the pump was operating below Minimum Continuous Stable Flow. To resolve this issue, one company engineered modifications to the casing and impeller.

Written by:
Dr. Gary Dyson, Hydro Global Engineering Services
Angelo Miller, Hydro Rocky Mountain
Eddie Janson, John Crane

Published by: World Pumps

Adjusting case piping

Figure 1: Hydro mechanics adjusting the case piping.

Vibration commonly causes pumps to operate at low flow and reliability plays a key role in the cost effectiveness of systems. The pump in question was an additive booster pump. The seal manufacturer contacted Hydro to collaborate. Hydro’s field technicians identified that there was excessive vibration which increased wear on the mechanical seal.

Hydro plotted the current conditions on the pump curve and determined that the pump was operating below MCSF for which performance factors such as efficiency, rotor dynamic stability, bearing and mechanical seal life become negatively affected, yielding a drastically reduced Mean Time Between Repairs/Failures (MTBR/F). The company performed an OH2 power-end upgrade and a pump hydraulic rerate.

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