TPS 2025: New Gas Seal Technology Eliminates Coke Formation

Chevron encountered persistent reliability issues with a traditional bellows seal: It was prone to coking, which is an accumulation of solid debris that interferes with sealing surfaces and eventually compromises performance, causes premature wear, and unwanted downtime. To address the challenge, Chevron partnered with John Crane to develop and install an advanced gas seal that would eliminate the problem.

At the 2025 Turbomachinery & Pump Symposia, John Crane’s Robert McManus and Jamie Cetrone discussed the new gas seal technology, its benefits, and how the design performed within a 2-year window for high-temperature hydrocarbon services. The new unit—a non-contacting gas-lubricated seal—eliminates the negative impact of solids, reduced Chevron’s downtime, and significantly minimized energy usage up to 90 – 95%.

Type 2874HTC non-contacting wet seal | Image Credit: John Crane

According to McManus, John Crane replaced the conventional bellows seal with a dual-pressurized metal bellows wet seal that uses gas rather than liquid support systems. The technology is built around a non-contacting, gas-lubricated concept that eliminates the need for cooling water and prevents solids from interfering with the sealing interface. At the core of the design are spiral grooves etched into the stationary seal ring. These grooves create a thin, stable fluid film between the sealing faces, enabling them to run without physical contact.

Tested to API Standards

Before installation, John Crane subjected the new design to an exhaustive series of tests to confirm its durability and reliability. Engineers carried out static and dynamic trials, reverse pressure tests, and solids and crystallization testing to replicate the conditions the seal would encounter in the field. The system also underwent qualification to API 682 dry gas seal standards, ensuring compliance with industry best practices.

Cetrone said that the testing validated the design’s ability to remain stable under variable conditions while maintaining the fluid film that protects the sealing faces. By resisting coking and crystallization, the seal demonstrated a significant improvement in performance over traditional bellows designs.

Installation and Cost Efficiency

Chevron’s upgrade demonstrated that installing an improved seal does not sacrifice operational uptime. Seal replacement can be completed within a single day, keeping disruption to a minimum. The cost of replacement, typically between $25,000 and $35,000, is modest compared with the potential savings in maintenance, reliability, and energy efficiency.

For operators, that speed and simplicity translate into both immediate and long-term value. The seal requires no auxiliary systems like steam quench, further reducing ongoing expenses and maintenance demands.

Benefits in the Field

Since installation, the new gas seal has logged more than two years of reliable service in Chevron’s system. During that time, the company has realized measurable benefits:

• Risk mitigation: By eliminating coking and solids-related interference, the seal reduces the likelihood of unplanned shutdowns.
• Simplified maintenance: With no need for steam quench or cooling water, technicians spend less time on upkeep.
• Reduced downtime: The stability of the non-contacting design ensures consistent performance.
• Lower energy use: The seal consumes 90–95 % less power than traditional wet seals, cutting both operating costs and carbon footprint.

These advantages combine to deliver not only operational improvements but also sustainability gains, helping Chevron align with broader efficiency and emissions-reduction goals. The success of Chevron’s project demonstrates the potential for advanced sealing technology to tackle long-standing industry challenges. Solids buildup and coking have been persistent problems across hydrocarbon applications, but John Crane’s dual-pressurized gas seal offers a proven path forward.

By combining robust engineering with field-tested reliability, the seal shows how incremental improvements to critical components can yield outsized benefits in safety, cost, and sustainability. For operators under pressure to maximize uptime while minimizing environmental impact, the Chevron case study provides a blueprint for future upgrades.

Check out more from TPS 2025, with coverage on sealless ammonia pumps, supercritical centrifugal pumps, and more to come!