Root Cause Analysis Uncovers Casting Defects

Efficiency and reliability are at the forefront of a successful pumping system. As such, unplanned outages can be a detrimental disturbance to the overall operation. In this case, the end user’s high pressure multistage  BB5 barrel pump was experiencing severe vibration, unstable performance, and failure in the field leading to unit shutdown.

This particular unit, used in boiler feedwater operations, is critical to the plant’s uptime and throughput. Furthermore, continued failures can cause growing costs due to inevitable maintenance and repairs, often overlooking a long term solution. With each unplanned outage, the plant could face a significant loss in capital.

Previously, the pump had been running for six months before experiencing catastrophic failure, requiring a shutdown and removal for further analysis. Initially, the unit’s damaged components were repaired by welding, and the volute was reassembled and installed for use. Upon its installation, the power plant placed the unit back into service but encountered a second emergency shutdown after two months in operation.

Video: https://vimeo.com/362808909

Source: https://www.pumpsandsystems.com/root-cause-analysis-uncovers-casting-defects-critical-boiler-feedwater-unit

Increasing MTBR Under Emergency Conditions

increasing mtbr under emergency conidtionsAs the nuclear industry continues to adapt to new requirements under the Nuclear Promise, it is of key importance for utilities to strengthen existing safety protocols and execute efficiency improvements in day-to-day operations and maintenance to optimize overall costs.

One such nuclear plant found themselves  struggling in regards to a planned outage of a vertical service water pump, providing cooling water to safety-related heat exchangers in the power generation process. In this case, the operating pump was actively exhibiting performance issues and was reaching the end of its lifecycle, requiring their reserve unit be placed into service under expedited conditions.

The principle goal for the plant was increasing Mean Time Before Repair (MTBR) of their pump system to optimize efficiency and reduce costs. Unfortunately, upon initial review of the reserve unit, it was identified that it had a history of poor performance issues under previous use.

Authored by Faisal Salman.
Source: nuclearplantjournal.com

Shortcuts Can Lead to Disastrous Outcomes

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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