Common Pump Seal Failure Causes—and How to Avoid Them

It’s the headline we all dread: Fire at Petrochem Refinery Triggers Local Evacuation. Perhaps the story starts with a pump seal leak that the emergency response team felt posed little danger to the community. And then the fire unexpectedly swells. Fortunately, most pump seal failures don’t lead to such dramatic consequences but they are no less important to address early on.

In my years of working with reliability engineers in the petroleum industry across Northern California, I’ve identified three principal categories of pump seal failure causes—outdated design, improper installation, and reactive maintenance. These three categories apply equally to pump seals and seal support systems. By understanding the genesis of the most common failure types, you can largely avoid them with proactive planning, vendor guidance, and outsourced assembly solutions.

Mitigate Failures With Pump Seal Design Improvements

If you’re installing a pump, seals, and support system for a new process, you have the benefit of employing the latest improvements in pump seal design. These advancements include better centrifugal pump efficiency and a wide variety of seal face materials engineered to better withstand harsh or demanding petrochemical processes. We also now have dozens of API 682 Standard Plans with many optional components to ensure pump seal reliability.

With respect to design, older seals and support systems like those found in the older refineries in the Bay Area often fall short. While the designs of those pumps, seals, and support systems likely offered the best solutions at the time they were installed, design and material improvement of today’s solutions provide far greater reliability.

As you inventory and assess pump assets, look for those whose repair history indicates declining efficiency. Prioritize those for upgrades or replacement and select the pumps, seals, and seal support systems that incorporate the latest materials and technologies designed to meet your specific process requirements. 

Match Seal Support Systems To Specific Requirements

Choosing the appropriate seal support plan is the most important decision you’ll make to avoid pump seal failure causes. The API 682 Standard offers dozens of plans with options to address pump seal support needs. Options can be overwhelming, but the guidance of an experienced seal support systems vendor will help you select and configure the systems to meet your specific requirements and maintain the optimum pump seal conditions. 

The vendor will lead you through the seal support system options, which fall into three categories—process side, between seal, and atmospheric side. Let’s take a look at each to understand their capabilities and uses.

Process Side Plans (Flush)

Process side plans circulate process fluids through a flow control orifice to the seal chamber, removing heat and ensuring proper pressure to prevent vaporization of the pumped fluids. Numerous variations for both horizontal and vertical pumps are available. Optional strainers and cyclone separators can be added to some of these plans to remove particulates from fluid that can damage seal faces. 

Between Seal Plans (Barrier/Buffer)

Between seal plans provide unpressurized or pressurized fluids between dual seals, adding a level of protection to prevent leaks—especially of volatile fluids. A buffer fluid seal pot, for instance, uses a reservoir to circulate unpressurized buffer fluid between the inboard and outboard seals. This prevents process fluids, such as light hydrocarbons, from leaking into the atmosphere. 

Buffer and barrier gases, typically nitrogen, are supplied from an external source to provide a constant source of clean, dry gas between inboard and outboard seals. A regulator controls nitrogen pressure entering the seal chamber. Buffer gas serves as a containment seal in the event of inboard seal failure. Barrier gas is ideal for applications where process fluid leakage is unacceptable. 

Atmospheric Side Plans (Quench)

Atmospheric side plans are designed to prevent the formation of solids on seal surfaces and ensure moisture does not enter the bearing housing. Quench from the reservoir uses steam to prevent icing on the atmospheric side of a single seal, typically on vertical pumps. Similarly, quench from an external source delivers quench fluid—steam, clean water, or nitrogen—to the atmospheric side of the seal to prevent or clear solid formation from seal surfaces. 

Foundation Proper Pump Seal Installation is Key to Reliability

Poor pump installation is almost a guarantee of eventual failure. Each component from the foundation and baseplate anchoring to the seal support systems must be properly installed, configured, and tested. Misalignment, loose bolts, inadequate lubrication, or poorly configured support systems are all candidates for pump seal failure causes. Excessive vibration, worn bearings, inadequate flushing or cooling of seals will eventually cause leakage.

Pump installations for a new plant expansion project enjoy the benefit of a “clean slate” with regard to location and design of pumps and supporting infrastructure. On the other hand, replacement installations in older Bay Area plants may need to accommodate limitations imposed by existing infrastructure. For both, however, savvy engineers understand the importance of “getting it right the first time” to ensure pumps, seals, and seal support systems operate reliably from day one.   

Proactive Maintenance Mitigates Many Pump Seal Failure Causes

Alongside the proper selection of pumps, seals, and seal support systems, proactive preventative maintenance based on asset performance history is the ideal method to uphold their reliability. By using an enterprise asset management system that tracks the installation history and repairs, reliability engineers can determine the optimum maintenance schedules for pumps, based on usage, process type, and manufacturer recommendations. Data-driven maintenance has proven to optimize operational resources by mitigating pump seal failure causes before they lead to unplanned equipment downtime.  

Work With Local, Experienced Professionals To Avoid Typical Pump Seal Failures 

Selecting the right seal support systems for your plant is much easier when you work with experienced professionals who know the refineries in Contra Costa County and other California Bay Area regions. You need a local vendor with the expertise to help you stay in line with the Bay Area Air Quality Management District (BAAQMD) and California Division of Occupational Safety and Health (Cal/OSHA) regulations. Expect solid recommendations on the seal support system plans that best fit your needs and delivery of an expertly designed, tested, assembled, and warranties systems. Relying on local support also ensures readily available parts and supplies in the event you need immediate support and delivery. 

Swagelok Northern California can help you avoid common seal failures by guiding the selection of seal support systems then designing and assembling for your specific processing requirements. Contact our team today by calling 510-933-6200.

About Paul Lesnau | Sales Manager, Business Development Manager, and Field Engineer

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.