Although mechanical seal failure is a common and unavoidable problem as it gradually wears down over the years, it is possible to reduce the downtime that may follow system failure. This should start with constant monitoring for any system failure and assessing for the mechanical seal support leak rate. The aging support system, improper installation, use of incorrect fluid, and inadequate maintenance are common causes of leaks and system failure.
Mechanical seals require lubricating buffer/barrier fluid to function smoothly. The improper use of these fluids can damage the seal and increase the mechanical seal support leak rate in more than one way.
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When lubricating fluid is not used |
Without lubrication from barrier/buffer fluid, the seal runs dry. Damage worsens when a pump runs dry. The excess friction and resulting heat due to lack of lubrication can result in burning or melting the seal, causing leakage. |
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When lubricating fluid mixes with process fluid |
It is not uncommon for the buffer/barrier fluid to mix with the process fluid to an acceptable limit. But if the process fluid is highly-viscous, its mixing with lubricating fluid can plug the seal, affecting the flow in the system. Without regularity of flow, the seal can leak due to overheating. |
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Incorrect selection of lubricating fluid |
Incorrect barrier/buffer fluid selection has a negative impact on the cooling and lubricating functions required for the process. Micro cracks may develop in the seal faces, causing leakage. |
Every mechanical seal, support system, and pump is manufactured to withstand a certain process specification. A minor discrepancy beyond the set pressure, temperature, or chemical specifications can shock the system, leading to leakage or failure of the seal support system.
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Temperature rise |
Degradation of seal faces and secondary seal components |
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Pressure fluctuation |
Failure of seal support system to provide adequate pressure in the seal chamber |
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Excess particulates |
Quicker abrasion of the seal face due to less than required lubrication |
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Change in chemical concentration |
Degrade/corrode seal face due to the use of incompatible material |
The seal support system is designed to preserve the integrity of the mechanical seal through functionalities such as minimizing vibration effect and providing ideal operating conditions within the seal chamber for flow control. The constant movement of the rotating equipment can lead to:
It is advised to replace the pumps, seal support system, and related components once its intended operating span has expired to avoid additional damages and to prevent multiple failures at once.
With constant monitoring of the process, optimization of the process conditions, and regular preventative maintenance of the support system, operators can identify the irregularities and leaks in time. However, the biggest challenge in identifying the root cause of seal support system leakage is that, oftentimes, it is the result of multiple components not working in conjunction. Pinpointing the actual cause of a mechanical seal support leak can be effectively done in collaboration with your local fluid systems expert.
If you need an expert’s outlook or a second opinion for your equipment or facility, Edmonton Valve & Fitting is here to help as your local troubleshooting partner in Alberta. Our expert Field Advisors can test and evaluate your seal support system on-site and recommend the design modification and component selection required to minimize the mechanical seal support leak rate at your facility. Through specific troubleshooting or full system evaluation, we can help improve the reliability, safety, and efficiency of your operation.