In a webinar hosted by LNG Industry, Emerson’s Joe DeMonte and Caitlin Carroll drew on the company’s 50-plus years of liquefied natural gas (LNG) experience to walk through the valve challenges that run across the entire LNG value chain, from inlet feed gas through liquefaction, storage, and marine transport. With over 70 percent of global LNG flowing through Emerson valves, the pair shared practical lessons on sizing, selection, and monitoring applicable to new mega-projects, de-bottlenecking efforts, and aging infrastructure alike.

Why it Matters

Global LNG demand is forecast to reach 630 to 718 million tons per annum by 2040, and a wave of new projects is racing toward startup before the end of this decade. Poorly specified or undersized valves in critical services can cause unplanned shutdowns, fugitive emissions, and safety incidents, so getting valve selection right at the front end of a project and revisiting it whenever process conditions change are among the highest-leverage actions an operator or engineering contractor can take.

Key Takeaways

• Inlet feed control valves require noise-abatement trim, spoked plug designs, and oversized actuation to handle the extreme flow rates and vibration at the front end of an LNG plant.
• The rich amine letdown valve is an outgassing application, not a flashing one; treating it correctly at the source prevents trim damage, stem breakage, and oversizing errors.
• Joule-Thomson valves operating at cryogenic temperatures demand factory-tested dynamic performance, low-friction cryogenic seals, and compliance with emerging International Society of Automation (ISA) cryogenic seat leakage standards.
• Pilot-operated pressure relief valves (PRVs), particularly the Anderson Greenwood 9300H for low-pressure marine service and the Anderson Greenwood Series 200 for high-pressure applications, deliver the seat tightness and capacity LNG operations require.
• Real-time PRV monitoring using Rosemount differential pressure transmitters turns a relief event from a binary “open or closed” report into a quantified record of duration, magnitude, and product loss.

Control Valves at the Heart of the LNG Train

Joe organized his discussion around four control valve applications that, if any one fails, can shut down an entire LNG train. At the inlet facility, where large-diameter pipelines deliver feed gas at high pressure, the primary enemies are noise, vibration, and plug instability. He recommended multiple valves in parallel, with at least one smaller trim valve for startup and seasonal conditions, paired with Fisher spoked-plug designs that reduce the surface area exposed to turbulent flow. Every critical valve, he stressed, should carry a smart positioner with online diagnostics so that tubing leaks, control drift, or impending failures surface before they force a trip.

The Amine Letdown Lesson: Outgassing, Not Flashing

One of the most actionable segments focused on the rich amine letdown valve at the bottom of the acid gas absorber. Joe explained that process data often makes this look like a flashing application because inlet pressure sits close to the fluid’s vapor pressure. In reality, the process fluid is not pure; dissolved carbon dioxide comes out of solution as pressure drops, much like opening a carbonated drink. Mistaking outgassing for flashing leads to oversized valves and controllability problems.

Joe shared a Gulf Coast success story in which a customer replaced a competitor’s valve that was causing plant trips due to excessive vibration across an 800-plus-psi pressure drop. Emerson delivered a complete solution, including dirty service trim produced through additive manufacturing in a hardened material, in nine and a half weeks against a 12-week turnaround window. The replacement has been running for over a year, and the customer is now extending the solution to additional trains.

Cryogenic and Anti-Surge Demands

Joule-Thomson valves sit at the coldest point in the process, where even small seat or packing leaks can result in lost cargo. Joe cited a case where an operator was losing multiple cargoes per year because a competitor valve had to run in manual mode. Replacing it with a properly sized Fisher globe valve with cryogenic extension bonnets and factory-verified dynamic performance eliminated those losses.

On the compression side, anti-surge valves must open within milliseconds to protect multi-million-dollar compressors from surge events that can damage them. Joe recommended factory testing every anti-surge valve to the compressor vendor’s specifications and equipping it with partial-stroke testing capability, because many of these valves sit on the seat for months and must perform the instant they are called upon. For customers unsure where to start, Emerson offers a factory test specification as a reference.

Pressure Relief across the LNG Value Chain

Caitlin shifted the conversation to pressure relief valves (PRVs), where the twin challenges are cryogenic performance and fugitive emissions. For low-pressure tank and carrier service, she highlighted the 9300H pilot-operated relief valve, developed specifically for marine applications and certified by major classification societies. The 9300H’s market-leading flow capacity can reduce the number of tank penetrations or the required valve size, lowering weight, maintenance burden, and associated piping costs.

For high-pressure applications, the Series 200 pilot valve, proven across more than 80 LNG sites worldwide, uses a flexible soft seat to maintain bubble-tight sealing to at least 95 percent of set pressure while resisting icing at cryogenic temperatures.

Caitlin also introduced a monitoring layer: Rosemount differential pressure transmitters installed on pilot-operated PRVs that capture when a valve opens, how far it opens, and for how long. In one case, this approach helped an LNG carrier operator monitor vacuum relief events on membrane tanks after the original valve supplier exited the market, giving the crew real-time insight into under-pressure conditions that could allow atmospheric air into the tank.

Get Started Early

Both Joe and Caitlin stressed that the best time to engage a valve partner is as early as possible, and not only for new projects. De-bottlenecking activities, planned turnarounds, and maintenance windows are all opportunities to reassess critical valve applications and optimize solutions before small issues become costly shutdowns. Explore Emerson’s full portfolio of flow control, pressure relief, and monitoring solutions for LNG.