No matter which Northern California petrochem refinery you work in—Concord, Martinez, or Benicia—the scene is common. You get the maintenance ticket for a horizontal pump that you’ve never done planned maintenance on before. It’s leaking. The pump hasn’t been shut down, but when you get there it becomes clear that mechanical seal failure is the root cause of the problem.
You check the maintenance log and find that the seal was installed less than a year ago. Per the API, mechanical seals should last an average of three years. A quick review of the immediate pump environment reveals no obvious issues. What’s the problem?
I’m here to help you sort it out.
You’re probably familiar with the truism that mechanical seals fail when the seal support system no longer provides the required seal chamber environment to ensure reliable operations. To be a bit more specific, two major seal support system issues—temperature and particulates—inevitably lead to mechanical seal failure.
Let’s look at each of these with an eye toward proactively addressing the problems to prevent failure.
Changes in process fluid temperatures and/ or a seal support system’s inability to efficiently control seal chamber temperature can slowly, or in some cases, quickly lead to leakage. In older Bay Area refineries, seal support systems installed years ago, intended for certain process conditions, now contend with higher process fluid temperatures. As a result of elevated temperatures, there are a variety of effects:
The inability of a seal support system to maintain the proper temperature in the seal chamber can be the result of numerous factors. The table below summarizes the issues and offers practical solutions to address them.
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Seal Support System Issue |
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Inadequate cooling capacity |
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Insufficient fluid circulation |
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Seal chamber pressure increased by steam flush |
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Unexpected shutoff of barrier/ buffer fluid |
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| Worth considering: Although not directly a part of a seal support system, the addition of a thermal bushing or heat slinger in the seal box can significantly limit high-temperature process fluids from migrating into the seal chamber and reducing mechanical seal life. |
As mentioned above, an increase in fluid temperature eventually correlates with increased corrosion throughout pipes and pumps, posing the potential to damage mechanical seal reliability. An increase in process fluid particulates, whether by corrosion or inherent in the process fluids, can lead to:
Effective remedies for particulates include:
⇒ Upgrading to inline, serviceable (in situ or once removed) T-type, F, FW, or TF filters with appropriate pore sizesProtecting pumps from the plague of corrosion via better filtering may be one of the easiest means of improving pump reliability.
Proactive identification and remedying of these seal support system issues are the most cost-effective means to reduce unplanned downtime caused by pump leakage. But it’s not always a simple matter of “ordering from the catalog.” Upgrades and replacements should be undertaken with a holistic approach.
Consider some of the many factors involved in selecting the right seal support system configuration for petrochem processing:
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Guidance from experts who have “been there, done that” can simplify the complexity of upgrading or replacing inadequate seal support systems.
At Swagelok, I’ve worked with rotating equipment engineers across Northern California refineries to find the right seal support solutions to meet their process needs. Our experienced Field Engineers consult with you at the plant to review the challenges in context of the specific pumping operations. You’ll get recommendations including detailed technical specifications, based on API 682 plans and configuration options to address these common seal support system issues.
Upon your review and approval of Swagelok recommendations, we’ll then select the components, fabricate and test your seal support systems following the ISO 9001 process quality standards prior to delivery. Being local, with facilities in Fremont and Concord, we’re always available for technical support by phone or onsite.
To find out more about how Swagelok Northern California can help address common seal support system issues by providing expert consultation and Assembly Services, Contact our team today by calling 510-933-6200.
Paul holds a B.S. in Mechanical Engineering from North Dakota State University. Before joining Swagelok Northern California, he was the West Coast Regional Sales Manager for an organization based in Illinois involved in pneumatic and hydraulic applications where he supervised product distribution throughout the western United States, Canada, and Mexico. While in this role, he was able to help provide technical and application-specific expertise to customers and distribution to drive specifications.