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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How Root-Cause Analysis Solved a Vertical Turbine Pump Failure

A comprehensive approach to reverse engineering helped to establish the differences between the stainless steel and original bronze impellers.

Written by:  Hydro, Inc.
Publisher: Pumps & Systems / March 2016

 

When a severe pump failure involving one of three installed circulating water makeup pumps happened, facility personnel grew concerned about the root cause. The subject pump failed just 40 days after its commissioning.
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Image 1. A crack in the discharge head flange that involved fatigue failure of the weld of a pump.

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Image 2 (right). The pump’s impeller wear ring landing shows heavy scoring.

The equipment in question consisted of three-stage vertical turbine pumps running either in standalone or in parallel operation as required. The failure manifested itself through high vibration and caused severe scoring of the pump shaft and wear ring landings, leading to fatigue failure of the weld on the discharge head flange (see Images 1 and 2). The commissioned pump was refurbished and rebuilt by another company’s service center with spare impellers supplied by an original equipment manufacturer. No changes to the geometry had reportedly been made, although the impeller material had been upgraded from bronze to stainless steel.

The plant initiated its internal root-cause analysis process, and the failed pump required emergency repair. The station sought a company to conduct the repair, and the firm reviewed the customer-supplied documents and background providing the possible causes of the failure. Continue reading