The LM2500+G4 is an advanced variant of the LM2500+ aeroderivative gas turbine, designed to provide increased output and thermal efficiency through a set of targeted design upgrades. It retains the core architecture of the LM2500+ but introduces changes to the flow path that increase overall engine performance.

The primary difference between the LM2500+G4 and the LM2500+ is the increased flow capacity in the high-pressure (HP) compressor, HP turbine, and low-pressure turbine. These modifications raise the overall pressure ratio from 23.6 to 24.2, resulting in higher thermal efficiency and greater mass flow. The design changes are relatively limited, focusing mainly on minor geometry adjustments to blades and vanes to accommodate the increased flow.

In the high-pressure turbine, the G4 version includes improved blade cooling and upgraded materials. These changes enable the turbine to handle higher temperatures, contributing to both improved performance and component durability. To maintain proper rotor thrust balance with the updated flow path, the effective area of the compressor discharge pressure seal was also adjusted.

In terms of operational performance, the LM2500+G4 offers measurable improvements over the LM2500+ across a variety of ambient conditions. For example, it delivers approximately 11% more power in cold conditions and 12% more in hot conditions (running data to -50 deg F and start data to –40 deg F). In combined-cycle mode, the G4 variant is expected to provide a power increase of 8.5% and a heat rate improvement of 0.75% compared to the LM2500+.

The LM2500+G4 supports two power turbine configurations:

• A six-stage, low-speed power turbine, typically used for power generation applications with a nominal speed of 3600 rpm.
• A two-stage High-Speed Power Turbine (HSPT), used for mechanical drive applications, designed for a nominal speed of 6100 rpm, with an operating range from 3050 to 6400 rpm.

Both configurations support operation over a cubic load curve, which allows the turbine to match power output with varying mechanical loads — a feature especially useful in pipeline compression and similar variable-load industrial applications.

The T5.4 thermocouple is a temperature-sensing probe used in LM2500 gas turbines to measure exhaust gas temperature (EGT). The label T5.4 refers to its specific position in the turbine\'s exhaust thermocouple array—zone T5 (turbine exhaust), sensor 4. These sensors are part of a system that monitors thermal conditions at multiple points in the exhaust stream.

This thermocouple operates in high-temperature environments, withstanding continuous exposure up to approximately 1100°C. It is built to maintain accuracy and reliability under the thermal stress and vibration typical in gas turbine applications.

T5.4 thermocouples are often used with flexible

harness systems. This allows operators to replace individual probes without removing the entire harness, improving maintenance efficiency and reducing downtime.

By providing real-time exhaust temperature data, the T5.4 thermocouple supports engine control, performance optimization, and safety monitoring in industrial gas turbine operations.

The Packing O-Ring is a sealing made from durable fluorocarbon rubber, designed for use in high-temperature and chemically harsh environments. Commonly used in gas turbines such as the LM2500 series, it provides a tight seal between components to prevent the leakage of fluids or gases.

This O-ring has an inside diameter of 27/64 inches, a thickness of 5/64 inches, and a hardness of 75 Shore A. It is built to handle operating temperatures from -20°F to 400°F, making it suitable for sealing joints in systems exposed to fuels, oils, and high pressures.

Its compact size and resistance to compression set and fluid exposure make it ideal for use in shafts, housings, and valve assemblies where reliable sealing is critical to turbine performance and safety.

The LM2500XPRESS+G4 DLE UPT is a fast-deployable gas turbine system engineered for demanding oil and gas environments—onshore or offshore. It offers a balanced combination of power, efficiency, and installation speed, making it especially suited for upstream, midstream, and LNG operations where reliable electricity and mechanical drive are critical and timelines are tight.

At the core of this system is the LM2500+G4 gas generator, a proven design that delivers higher output and efficiency than earlier models, thanks to improvements in airflow, thermal capability, and cooling. It strikes a solid middle ground in the 20–40 MW class—powerful enough to support heavy oilfield infrastructure but lighter and more flexible than larger industrial turbines.

The Dry Low Emissions (DLE) combustion system helps meet environmental regulations without relying on water or steam injection—a major advantage for remote or offshore sites where water supply is limited or emissions compliance is strict.

The Upgraded Power Turbine (UPT) adds flexibility in terms of shaft speed and load-following, which makes this unit adaptable for various oil and gas power demands—from continuous baseload operation to backup and peaking support.

Its XPRESS configuration emphasizes rapid deployment. The turbine is delivered in a compact, modular format, pre-assembled into a small number of transportable units with simplified electrical and mechanical interconnections. This minimizes site work, shortens commissioning time to a matter of weeks, and reduces exposure to remote-site construction risks.

The LM2500+G4 SAC 50Hz Combined Cycle 1x1 is a gas turbine system that combines a gas turbine with a steam turbine to improve overall power generation efficiency. This configuration captures waste heat from the gas turbine exhaust and uses it to produce steam, which then drives the steam turbine, generating additional electricity. This approach helps maximize power output while making better use of fuel energy.

Building on the LM2500+ design, the LM2500+G4 increases power capability by about 10% without reducing the lifespan of critical hot section components. This is achieved by increasing airflow, enhancing materials, and improving internal cooling. Despite these upgrades, the core compressor and turbine stages, as well as most airfoil and combustor designs, remain consistent with the LM2500 model.

The LM2500+G4 features a 17-stage high-pressure compressor that raises the engine’s pressure ratio and airflow, boosting the total power output of the gas turbine to over 31 MW. It uses a Single Annular Combustor (SAC) equipped with water injection to help control emissions while maintaining stable combustion. The SAC’s simple, proven design provides uniform flame temperature and reliable operation.

This balanced system is common in industrial and energy applications where efficiency and power output must be optimized, especially under varying ambient conditions. The combined cycle setup offers a reliable and efficient solution for electricity generation in demanding environments.