Expansion Joint Challenges In Gas Turbine Exhaust Applications Design factors to consider when selecting your next GTX expansion joint.

Designing an effective custom expansion joint for a GTX (Gas Turbine Exhaust) application requires strict attention to a number of unique engineering problems. Typically installed in the vital space between the turbine and exhaust duct, a GTX expansion joint represents a single point of failure - if the joint fails, the plant ceases to operate as the turbine must be shut down. Therefore, when FlexCom engineers are tasked to design a custom expansion joint for a gas turbine exhaust system, we expect to face certain challenges common to most gas turbine applications, but unique compared to other industrial facilities.

Heat stress poses an intense issue to gas turbines, since the thermal state of a GTX system fluctuates severely during the course of turbine operation - particularly as the turbine starts. A gas turbine initiates from a cold state to extreme heat very quickly, subjecting an expansion joint installed on the exhaust outlet flanges to thermal shock. If the joint is not adequately protected against these rapid shifts in thermal stress, the heat will damage the joint and ultimately cause it to fail.

In addition to heat, vibrations and mechanical movement add significant stresses to an operating GTX expansion joint. As turbines and connected ductwork assemblies increase in size, power and temperature output, so too do they produce greater levels of duct movement and overall metallic vibrations. The turbulent flow of exhaust gas through the joint additionally increases vibration - as well as “flutter”, rapid shifts in gas pressure that can damage an unprotected fabric joint. These mechanical stresses can cause significant damage to an inadequately designed joint in a relatively short amount of time.

For gas turbine exhaust applications, we at FlexCom recommend using a flat belt composite expansion joint designed with highly temperature resistant fabrics. The fabric and stainless steel construction of FlexCom flat belts provide highly efficient movement compensation and vibration isolation, while our PTFE/fiberglass laminate fabrics reliably insulate the joint against the unique thermal stresses found in the exhaust duct of a gas turbine.

For hot-to-hot configurations (one in which both flanges must operate at the exhaust gas temperature), we also recommend including an accumulation pillow in the custom joint design. A pillow will reduce the overall temperature of the joint, as well as limit vibration transmission to the turbine outlet flange and help absorb ductwork movement stresses in these very high temperature environments.

Custom design of a gas turbine exhaust expansion joint requires a special level of engineering precision, as well as specialized expertise in compensating for the extreme stresses present in this type of exhaust ductwork. Don't risk your gas turbine operation on a lesser quality product - contact FlexCom offices today and let us show you how our custom designs deliver superior performance.

To learn more about the FlexCom 1800 Series flat belt expansion joint, visit us at www.flexcomonline.com!

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FlexCom Inc. 6864 Chrisphalt Drive Bath, PA 18014 Phone: 610-837-3812 Toll Free: 888-376-FLEX

• Expansion Joint Challenges In Gas Turbine Exhaust Applications
• Our Products: FlexCom 1800 Series
• About FlexCom Inc.

FlexCom Metal Bellows and
Metallic Expansion Joints.

A FlexCom® metal bellows offers an ideal solution to the problem of high pressure (up to 300 psi) liquid or gas transfer: flexible movement compensation coupled with highly durable thermal resistance, ideal for applications such as wastewater handling and desalinization.

A well designed custom metal bellows such as this, carefully engineered to fit detailed application specifications, can improve system predictability, reduce faults and improve overall application efficiency.

We've Moved!

Since 1991, Flexible Compensators (FlexCom) Inc. has focused its energy and resources upon the single task of becoming the industry leader in robust, dependable fabric and metal expansion joints. In 2008 we took the next logical step: moving into a new state of the art manufacturing plant. Our new plant in Bath, Pennsylvania today serves as our fully integrated and full service engineering, manufacturing and test facility.

Two-thirds larger than our previous plant, this new facility has effectively doubled FlexCom's production capacity, enabling us to offer even greater cost efficiency, quality control, fast shipping and customer service.