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.

Unseen Cost Factors

A Hydro sales representative met with the rotating equipment engineer for an initial
meeting. What was intended to be a half hour conversation turned into a two-hour
meeting. During the discussion, Hydro was able to point out the potential unseen cost factors that could come into play, and warned the client before work proceeded. The pump would potentially require reinstated fits and clearances after disassembly, affecting the cost of the repair. Not having this information beforehand the plant manager decided to go with Hydro.

The multiple shims originally installed caused the failure of the suction head gasket to the barrel, which was a low cost and inferior solution. The pump wasn’t producing at BEP due to a number of issues that could only be uncovered with a full forensic and engineering analysis.

Hydro suggested the plant have the pump sent to the HydroTex for analysis and repair. The client agreed, and the entire unit including the casing was sent to Hydro.

 

Figure 1. The pump as received.

 

Figure 2. Hydro utilizing ROMER technology, a precise tool when studying the condition of a pump.

The forensic analysis took roughly two days, and started by dismantling the pump. The inspection process found numerous problems, such as a damaged centering ring seat in the discharge cover. The barrel was removed and the volute assembly was uncovered. Hydro’s forensic analysis found that the suction pressure face was severely eroded due to insufficient gasket crush.

Hyrdo’s Solution

In creating a solution, Hydro outlined a scope of work, including a detailed in-process inspection, pump assembly and delivery, and pump installation. Hydro’s utilized their powerful engineering expertise to design a work scope. The work scope included upgrading the volute assembly with a new HP steel jacketed gasket, determining the new required shim thickness, installing the discharge cover with the proper shim and new gasket, and verifying bearing housing alignment and re-dowel as needed. Hydro also designed a volute locating ring and completed a full upgrade to the discharge cover and barrel casing to meet Hydro’s standards.

The solution was relatively simple, yet effective. Utilizing a singular shim prevented many issues the pump was experiencing. After installing the shim and the additional upgrades, the pump met BEP and was able to utilize much less energy to gain the required flow rate. The pump was working around the clock after the upgrade which only took five days.

Greatest compliment

A return customer is the greatest compliment and after the job was completed, HydroTex called the plant and a rotating equipment engineer went on site to ensure that everything was working as expected. “We greatly appreciate what your company did. Our operations and maintenance people reported that this was the easiest barrel pump they’ve ever started up.” said the rotating equipment manager. At the same time, Hydro was informed that they would become the preferred vendor. This case study clearly shows the technical equivalency and careful and detailed rebuilding processes that Hydro employs with BB5’s.

This article is published in February 2018 issue of World Pumps.

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