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Mechanical Seal Design Principles & Basics

mechanical seal support systems design principles
API Plan 74 with Optional Components

Better by Design: Swagelok Seal Support Systems

Swagelok leverages deep fluid system expertise to design and construct simple-to-configure, easy-to-maintain, and safe-to-operate seal support systems. If you are tasked with keeping rotating equipment online and operating efficiently, you will find that Swagelok mechanical seal support kits and assemblies are just what you need to minimize downtime, reduce costs, and save you time.


Swagelok’s standard designs adhere to best practices and incorporate all recommended components as laid out in API 682. To optimize the operation and service of your seal and pump, we go beyond the standards to design systems specific to your application. Choose from optional isolation valves, bypass loops, and instrumentation to help your pump operator easily maintain the system and monitor the health of the seal.


Swagelok mechanical seal support systems are designed and built by your local authorized sales and service center, making it simple to receive what you want when you need it.


Swagelok engineers leverage fluid system expertise and design practices that maximize your seal support system’s operation and encourage safe maintenance. Mechanical seal support systems, like all Swagelok products, are also backed by our Limited Lifetime Warranty.

Designed for Reliability and Maintenance

Swagelok design options include high-point vents in the seal support system, allowing systems to be vented and cleared of entrapped air to prevent flow or cooling disruption. Designs also may include low point drains to allow the system to be quickly and safely purged of buffer, barrier, or flush fluids when pumps are out of service. Many Swagelok seal support systems offer additional pressure and temperature measurement instrumentation options at points where having measurements would help troubleshoot an issue or provide other operational benefits.

Designed for Appropriate Flow

Whether the system delivers a flush fluid to the inboard seal or buffer and barrier fluids are circulated between seals in a dual seal arrangement, maintaining proper flow and circulation through the support system and seal chamber is a requirement for effective seal operation. Swagelok seal support systems are designed to with components such as filters and strainers located in easily accessible areas to simplify maintenance and minimize issues caused by clogs or unwanted flow restrictions. Additional options such as bypass loops can be added to the system to ensure a continued supply of flush fluid when a filter or strainer element is being replaced or cleaned. Tubing runs are also carefully designed, with best practices followed such as sloping all runs, eliminating the use of elbow fittings, and using large-radius bends in the tubing to further assist flow.

Designed for System Safety

Swagelok seal support system design options allow for customization to suit applications where high vibration levels, inadvertent contact by maintenance personnel, or other factors might create challenging conditions. The designs also incorporate block-and-bleed valves on all instruments, including gauges as recommended by API to provide an additional level of safety for items that need to be calibrated or removed for servicing. Wherever practical, Swagelok seal support systems offer options such as two-valve manifolds or other appropriate isolation on instruments.

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