Flow control is fundamental to liquefied natural gas (LNG) production, particularly during feed gas handling where conditions can change rapidly.
Many LNG facilities continue to rely on older valve designs, which can struggle to manage fluctuating pressures, temperatures, and flow velocities.
Advances in valve technology are helping operators improve process stability, reduce noise, and increase overall plant efficiency.
Flow Control Challenges in LNG Feed Gas Systems
Over the past 50 years, LNG processing has evolved significantly, but the demands placed on feed gas systems have also increased. Gas entering transmission networks often comes from multiple sources, each with different pressures and flow rates.
These variations can place significant strain on inlet valves, impacting:
Modern valve technologies are increasingly being used to address these challenges and improve overall performance in liquefaction processes.
Managing noise in LNG operations
Noise remains a key operational challenge in LNG facilities. Typical LNG trains can exceed 85 dB due to rotating equipment such as compressors, pumps, heat exchangers, turbines, and vent systems.
Compressors, in particular, operate at high rotational speeds to increase gas pressure before liquefaction, contributing significantly to noise levels.
In addition to mechanical sources, flow-induced noise is created when natural gas undergoes rapid changes in velocity and direction. This can result in:
Historically, noise concerns were largely confined to plant environments. However, increased urban development near industrial sites has made external noise impact a growing issue for surrounding communities. For example, residents in Milford Haven reported persistent low-frequency noise in 2020, later linked to LNG shipping activity in the area.
Designing a High-Performance Flow Control Solution
IMI has worked with a major LNG producer in the Caribbean operating four liquefaction trains with a combined capacity of 12 to 15 million tonnes per year.
The challenge involved upgrading an existing feed gas line to meet updated flow capacity (Cv) requirements. The original 24-inch line, paired with a linear globe valve, was found to be undersized against the required 36-inch specification.
To address this, IMI proposed a quarter-turn ball valve solution with higher flow capacity, designed to improve both safety and production efficiency. This solution was developed as the dBX Shield.
The dBX Shield is engineered to deliver improved flow control while reducing noise and optimising performance in demanding LNG applications.
DRAG™ Technology for Advanced Pressure Control
DRAG™ technology, developed by IMI in 1967, is a key innovation used in high-pressure drop and cavitation-prone applications such as LNG feed gas systems.
Unlike traditional one-to-three-stage pressure reduction methods, DRAG™ technology distributes pressure drop across more than 20 stages depending on operating conditions.
This multi-stage approach provides:
When combined with a quarter-turn trunnion-mounted ball valve, DRAG™ technology reduces both the size and weight of the overall solution compared with conventional globe valve systems, while improving sealing performance.
Continuous Innovation and Performance Improvements
Ongoing development of DRAG™ technology has incorporated additive manufacturing to optimise flow control elements and improve design flexibility.
These advancements enable incremental improvements without redesigning the entire valve system, supporting high-performance applications such as the dBX Shield.
In LNG service, the dBX Shield can reduce noise levels to approximately 60 dB in certain operating conditions, depending on system configuration.
Expanding Applications in Refining and Industrial Projects
The benefits of advanced flow control are not limited to LNG. In a major refinery expansion project in the Middle East, IMI supported a capacity increase from 265 MBPD to 360 MBPD.
The project required approximately 2,000 valves across steam, oil, and diesel applications, all meeting strict requirements including:
Traditional globe valve configurations were unable to consistently meet the minimum opening range requirements. Following consultation, IMI recommended a ball valve solution combined with dBX Shield technology, enabling compliance while reducing overall valve size.
Pump Testing and High-Demand Applications
The adaptability of the dBX Shield has also been demonstrated in pump recirculation systems.
At a centrifugal pump testing facility in the United States, cavitation damage to a 24-inch valve required a replacement capable of handling extreme operating conditions, including:
The new solution required high rangeability, durability, and ease of installation due to frequent configuration changes in the test environment.
A compact dBX Shield design with multi-stage pressure reduction was selected, providing up to 12 stages of pressure control and improved operational flexibility.
Additive Manufacturing in Valve Production
IMI has used additive manufacturing since 2010 to produce components for DRAG™ technology and related valve solutions.
This approach supports:
Additive manufacturing simplifies production, reducing raw material usage, delivery times, and ensuring consistency. With the gas industry facing increasing demand for fugitive emissions control – exemplified through standards such as ISO 15848, API 641 and API 622 – reducing areas of potential leakage is also a priority. Quarter-turn valves made using additive manufacturing techniques offer better sealing capabilities, reducing the possibility of fugitive emissions through static and dynamic joints alike. Consequently, their specification will be vital to reducing the LNG industry’s carbon footprint.
To overcome current size limitations in additive manufacturing, IMI has developed a method for producing DRAG™ flow control elements that are not constrained by machine build size.
Proven Performance in Critical Applications
Across global installations, IMI has delivered more than 160,000 DRAG™ trims and 14,000 isolation valves in applications where safety, integrity, and performance are critical.
The dBX Shield rotary control valve continues to demonstrate strong performance in LNG, refining, and industrial processing environments, combining:
Read more about dBX Shield and also how it transformed Middle Eastern refinery operations.