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A cold-storage facility recognized an issue concerning a failed mechanical seal on a Goulds 3196 ammonia pump. Because ammonia centrifugal pumps are critical to maintaining temperatures at a cold storage facility, identifying the problem and appropriate solution was dire. The facility's maintenance department and the engineering and service teams at Crane Engineering worked together to find the right solution.
This cold storage facility has two primary pumps used to maintain temperature throughout the facility. One of these pumps experienced catastrophic seal failure less than one year after it was replaced by the customer. To make things worse, the other critical pump wasn’t doing much better as it slowly leaked as well.
The customer was in a tough situation. Summer weather arrived – making it even more difficult to maintain the cold temperatures. Time was running out.
Instead of installing a new seal, the team at Crane Engineering stepped back to determine why the mechanical seal failed. Oftentimes there is an underlying cause for seal failures, especially when they happen within a short period of time. It was determined that seal selection was not the issue. This style of seal is commonly used across the cold storage industry and is widely accepted due to its reliability.
The pump was disassembled by Crane Engineering's service team in Kimberly, Wisconsin. The condition of critical parts was assessed to determine if replacing the seal would fix the problem. Many components showed significant wear. Replacing the seal would only be a temporary solution, as the worn components directly impact the overall reliability of the seal.
Worn components, such as a scored shaft or shaft sleeve, will damage the mechanical seal before it gets the change to run. Scored shafts and sleeves tend to damage o-rings as they slide on.
Bent shafts, old and out of spec bearings, and imbalanced impellers cause vibration, internal parts contact, and bearing damage, etc. All of these factors will shorten the life of the mechanical seal.
All used parts should be thoroughly inspected before reuse. They should meet factory specifications. If they don’t, they should be replaced.
A Crane Engineering Account Manager also noticed the seal’s piping plan wasn’t ideal. It sloped in the wrong direction with tight 90 degree elbows instead of gentle slopes. A proper pipe installation method was discussed and necessary changes were made to ensure adequate lubrication.
The last piece to any rotating equipment repair is to ensure proper alignment. If the alignment is off, it negatively impacts the life of the equipment. The facility had its own laser alignment equipment but opted to allow the service technician to align it himself. The service technician performed the laser alignment and noticed significant misalignment, which would have decreased the life of the pump.
The facility's maintenance team was trained on pump rebuild procedures and best practices to improve reliability and lower operating costs. The operators also learned how to become more efficient with future repairs.
The pump repair and installation took a total of two days. Many causes for the shortened seal life were found, and necessary components on the pump were either repaired or replaced. Since then, the pump has operated without issue. Plus, the maintenance team came out with a greater depth of knowledge on the subject.
Root cause analysis of the failed mechanical seal helped maintenance personnel extend the life of their pumps. They’re now minimizing costs associated with repeated mechanical seal failure.
Experiencing seal failure on your pump and unsure why? Ask us about it! We are happy to provide technical assistance to business and municipalities in Wisconsin, Upper Michigan, Minnesota, and Iowa.