Dry gas seals: 50 years of engineering progress in gas compression

Reliable gas compression under demanding conditions has always depended on the performance of the smallest components. For operators, that reliability translates into longer maintenance intervals, increased uptime, lower emissions, reduced operating costs and confidence that critical equipment will perform as expected. Few technologies illustrate this impact more clearly than dry gas seals.

As gas compression applications have become more complex and operating conditions more demanding, dry gas seal technology has evolved to meet those challenges. This year marks 50 years since the first large-scale, field-proven dry gas seal designs entered industrial service. It is a milestone that reflects not just a single innovation, but decades of engineering development shaped by changing industry needs and environmental expectations.

Reflecting on this history, John Crane's Senior Portfolio Director, Nico Schmaeling describes dry gas seals as “one of the best examples of engineering solving the problems that stand in the way of progress.” That perspective frames a story that stretches from early research efforts in the 1960s to today's digitally enabled, high-performance sealing solutions.

Solving a critical challenge in rotating equipment

Dry gas seals are only one component within a compressor, yet their role is fundamental to the operational success of the compressor. The pressures, temperatures and speeds at which they operate place mechanical seals under constant stress, making their reliability critical for plant availability and safety.

In the 1970s, centrifugal compressors in the oil and gas industry relied primarily on oil-lubricated wet seals. While effective for their time, these systems required complex support infrastructure, generated waste and demanded regular maintenance. The result was higher operating costs and growing environmental concerns as compressor duties increased and expectations around emissions began to change.

Industry needed an alternative approach—one that could support more demanding applications while improving reliability and efficiency. Research and development teams had already begun exploring non-contacting, gas-lubricated sealing concepts in the late 1960s. In 1970, this work led to the first U.S. patent for a modern dry gas seal, awarded to John Crane.

The concept offered clear advantages:

• Reduced wear through non-contacting operation
• Improved reliability and longer service life
• Increased efficiency through lower friction
• Reduced harmful emissions compared with oil-based systems

At a time when environmental considerations were becoming increasingly important, dry gas seals offered a practical way to improve both operational and environmental performance.

1976: From concept to industrial reality in gas compression

The transition from a promising concept to an industrially proven technology occurred in the mid-1970s. By 1975, the first commercially significant spiral groove gas seal, patented by John Crane, had entered field trials. A year later, in 1976, the first large-scale, field-proven dry gas seal designs were introduced to the market.

John Crane's Type 28 was among these early designs, helping to establish non-contacting sealing as a practical solution for industrial-scale turbomachinery. The operating principle was straightforward but transformative. Precision-cut grooves draw process gas between the seal faces, creating a stable gas film that separates them during operation. This eliminates contact during running conditions, enabling friction-free operation and significantly reducing wear and leakage.

For industries dependent on centrifugal compressors, including oil and gas, chemicals and petrochemicals, the impact was immediate:

• Improved compressor reliability
• Extended maintenance intervals
• Lower emissions
• Reduced operating costs

This period marked a turning point in how engineering solutions were applied to real-world industrial challenges, setting a new benchmark for gas compression performance.

1980s-1990s: From breakthrough to benchmark

Once dry gas seals demonstrated their value in the field, development accelerated. Throughout the 1980s and early 1990s, the technology expanded into increasingly demanding applications and environments. These included offshore platforms, liquefied natural gas (LNG) facilities, hydrogen recycle compressors, ethylene refrigeration systems and ammonia service.

Engineering focus during this period shifted toward accommodating a wider range of compressor types and operating conditions. Key areas of development included:

• Elastomer-free seal designs
• Advances in mechanical seal face materials
• Early analytical methods to better understand gas film stiffness and dynamic behaviour

As designs matured, new mechanical seal families emerged, each addressing specific reliability and performance challenges. These advances coincided with increasing process complexity across industries, helping establish dry gas seals as the preferred sealing technology for modern turbomachinery.

2000s: Engineering for extreme operating conditions

Over the past two decades, dry gas seals have been applied in environments that would have seemed ambitious when the technology first emerged. Today, seals operate at pressures above 420 barg and across extreme temperature ranges, from cryogenic LNG applications at -160°C to high-temperature power loops.

At the same time, the energy landscape has continued to evolve. Dry gas seals have become integral to:

• LNG megatrains
• Floating LNG (FLNG) units
• Hydrogen compression systems
• Carbon capture, utilisation and storage (CCUS) applications

Reliability requirements have increased across these advanced applications. The technology has continued to evolve in response, maintaining performance under increasingly demanding conditions while supporting new energy pathways.

Reducing emissions and supporting sustainability goals

One of the most significant contributions of dry gas seals is their impact on emissions and sustainability.

Removing oil lubrication systems reduces power consumption, enabling facilities to lower energy use over the operating life of their equipment. Across hundreds of compressors globally, John Crane's wet-to-gas retrofit programmes—part of the John Crane Performance Plus™ service solutions—are in place. These deliver substantial reductions in CO₂ emissions each year.

More recent engineering developments have continued this trend. Modern separation seal designs, such as the Type 93AX, can help reduce nitrogen consumption by more than 90% compared to traditional labyrinth seals. These improvements help plants reduce N₂ costs while supporting broader efficiency and sustainability objectives.

Digital monitoring and operational insight

As operating conditions have grown more demanding, the need for real-time insight into equipment health has become increasingly important. Mechanical reliability issues can develop rapidly, and traditional inspection intervals are often insufficient to address these issues.

Digital monitoring systems, such as John Crane Sense® Turbo, were developed to address this challenge. These near real-time systems provide continuous visibility into mechanical seal health using acoustic, temperature and liquid data. Operators receive early warnings when operating conditions move outside normal parameters, enabling proactive intervention.

The benefits of digital monitoring include:

• Extended seal life
• Reduced unplanned downtime
• Protection of critical rotating equipment
• Improved operational decision-making

By combining advanced sealing technology with digital readiness, operators can better manage risk in complex operating environments.

Engineering for the next era of energy

Hydrogen, sustainable fuels, CCUS and increasing electrification are introducing new mechanical demands for compressors. Higher speeds, wider temperature ranges and stricter leakage requirements are becoming standard expectations rather than exceptions.

Dry gas seals are positioned to meet these requirements. The engineering foundations established over the past 50 years remain relevant, supported by continued advances in materials, design resilience and monitoring capability.

Celebrating 50 years of innovation and enduring impact

As the next generation of energy systems takes shape, dry gas seal technology will continue to evolve—driven by the same principles that transformed gas compression five decades ago. “Innovation is never static. Our commitment to evolving with industry challenges is what has kept dry gas seals relevant for 50 years, and it's what will keep them essential for the next 50,” Schmaeling envisions.