Corroded Steel

Fertilizer Focus: Volute Reprofiling Resolves Vane Pass Vibration

A hot potassium carbonate pump at a nitrogen fertilizer plant had been experiencing elevated vibration at vane pass frequency. Recognizing that this vibration likely contributed to shortened equipment life, the end user partnered with Hydro to investigate the root cause of the vibration and modify the pump as necessary to remove it.

When the vibration and performance indicated that it was time to take the pump out of service for refurbishment, it was sent to Hydro’s Chicago service center for inspection and analysis. The inspection showed significant damage caused by component contact and erosion.

After reviewing the inspection data, an engineering analysis was completed on the design to determine what could be done to eliminate the vibration. The engineering team determined that the vane pass vibration was related to shock waves caused by the high energy fluid impacting the volute lip. This was intensified in the first stage, where the 4-vane impeller was discharging into a dual volute. The volute lip was reprofiled to reduce this impact and provide a smoother transition from the impeller exit into the volute passage.

The upgraded design was tested in Hydro’s performance test lab. This gave the end user confidence that the hydraulic performance of the pump had not been negatively affected by the volute lip geometry modification. It also verified that the vibration amplitudes had been reduced. After successful testing, the modified pump was returned to the field, where it continues to run smoothly.

chart, bar chart

1. Reduced Vane Pass Vibration Observed During Testing

Re-engineering System Reliability

A US fertilizer plant was experiencing recurring reliability problems with its horizontal multistage boiler feed pumps. The series of repeat failures motivated the owner plant to consult with a widely-known unbiased ­­­­aftermarket pump service provider. Previous experience with this company’s Texas facility gave the plant confidence that they had the capability to troubleshoot the problem and provide a solution. This type of supplier has been classified as a “CPRS”— Competent Pump Repair Shop, because their worldwide affiliates are staffed by specialists who have the fullest support of pump engineers at the company headquarters.

The aftermarket pump service provider performed a failure modes and effects analysis (FMEA) that took into consideration historical failure information and included an independent engineering analysis of the operating conditions. A review of the system history uncovered that the fertilizer plant had originally been designed with two 100% pumps. When the system was uprated, increased output requirements necessitated that both pumps operate in parallel to meet the new demand. Based on this information, the FMEA determined that the most probable failure mechanism was discharge recirculation caused by low flow operation.

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Unearthing the Root Cause of Vibration Issues

recently constructed fertilizer plant was experiencing significant vibration problems on their brand new UAN Solution pumpsThis vibration forced the plant to take the equipment out of service.   

The site was unable to diagnose the root cause of this problem on their own and the unreliability and resulting unavailability of this critical equipment was causing significant stress on the new plant. They heard through another fertilizer plant that a global aftermarket pump service provider had been able to diagnose and remediate their pump problems with great success. The site reached out to this aftermarket pump service provider to help identify the issue and provide solutions.   

The pump was shipped to the aftermarket pump service provider’s Chicago repair shop to perform a thorough disassembly, cleaning, and inspection (DCI). The service provider’s engineering team reviewed the original pump design and historical vibration information provided by the plant. Between this review and the DCI results, sufficient evidence was gathered to perform a root cause analysis (RCA) that explained the aberrant behavior of the problem pumps. The pumps were then re-engineered to eliminate the diagnosed problem and provide the plant with reliable operation.   Continue reading

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

Hydro Middle East performs swift re-build on fire-damaged circulating pumps

Hydro Middle East, specialists in pump rebuilding, particularly in the oil and gas industry and other industrial markets was called in to assess the damage and redesign and rebuild the fire-damaged pumps. Hydro’s engineers first evaluate the causes of any pump damage or failure and then provide expert engineering analysis and a responsive field service.

Written by: Thomas Arakal (Hydro Middle East)
Published by: World Pumps

Two fire damaged pumps

Two fire damaged pumps arrive at the Hydro Middle East Service Centre.

Analysis & recommendations

In the case of the fire-damaged pumps, once the fire was under control, Hydro immediately sent a field engineer to the site to conduct a root cause analysis and make recommendations to ensure that the equipment would be restored within the very fast turnaround that the company required.

The engineers discovered that the fire had been so severe it had completely burned out all of the oil in the bearing housing. In addition, the baseplate was also warped because of the excessive heat. A turnaround of between two and three weeks for redesign and rebuild was proposed, subject to mechanical seal availability and the two hot oil circulating pumps, along with the baseplate and the motors were shipped to Hydro Middle East’s facility in Dubai, U.A.E.

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