Tag Archives: damage

Machined centrifugal pump

Maximizing Efficiency in Descaling Pumps

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descale pump impeller damage

Damaged impeller showcasing severe corrosion.

A major steel plant on the East Coast had been experiencing catastrophic failures with its five-stage descaling pumps. 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. In this case, the plant water quality was considered to be less than ideal, and the entrained abrasives were a factor contributing to the repeated failures.

Poor water quality can lead to a number of pump reliability issues. When pumping fluids with abrasive material, pumps experience erosion and corrosion, and the effects can rapidly degrade both the casings and critical inner elements. While erosion and corrosion alone are not always a difficult problem to solve, it is important to have a firm understanding of the relationship between various types of erosion and corrosion and the metallurgy used in designing the pumps.

Further analysis showcased excessive clearances and inconsistencies with component fits that also contributed to pump performance degradation outside the abrasion. In order to increase the MTBR of the pumps at the plant, the aftermarket pump service provider recommended several engineered upgrades including new impellers to be manufactured using advanced mold technology, specifically addressing the surface finish and dimensional consistency.

Source: https://www.pumpsandsystems.com/maximizing-efficiency-descaling-pumps

Shortcuts Can Lead to Disastrous Outcomes

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Design flaws cause catastrophic failure in a geothermal power station hotwell in New Zealand.

Written by: Chandra Verma (Hydro, Inc.)
Publisher: Pumps & Systems / August 2016

 

Despite well-documented pump system standards and basic requirements, omission of certain crucial design steps remains a problem in the industry, often causing disastrous outcomes for the end user. When suppliers, manufacturers and/or contractors take shortcuts, technical and commercial risk can present serious ramifications for a large project.Communication failures between the end user’s staff, suppliers and contractors can intensify problems, especially when pumps that may not be appropriate for a given job are commissioned and put into service. Without the end user’s knowledge, a facility may install pumps that have not been properly tested for the application, were fabricated to inferior standards or subject to other shortcuts that adversely affect performance.Sometimes the end user becomes aware of shortcut-derived flaws during the commissioning stage. Other times, problems in equipment or system design might not be evident immediately—they surface during subsequent plant and equipment maintenance that reveals potentially dangerous, hidden conditions. The ensuing problems can lead to tense project politics and expensive rectification, including hiring independent consultants.

Suppliers, manufacturers and contractors take shortcuts for various reasons. These shortcuts can be attributed to a lack of experience with how a pump might be deployed in the field. There may be miscommunication of technical details from both the user and supplier or between the user and contractor.

Budget constraints and concerns can also result in omissions; commercial reality can cause a manufacturer or supplier to make a project’s bottom line cheaper by reducing the cost of equipment and cutting corners.

fig-5d-aandb-velocity-dist

Figure 1. The velocity distribution of the original (left) and modified geometries (right)

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