Toll-Free: 888-376-FLEX
Phone: 610-837-3812
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Expansion Joint Challenges In Gas Turbine Exhaust Applications

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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 duct 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 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 (GTX) 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 – call FlexCom offices today and let us show you how our custom designs deliver superior performance.

NV Energy Case Study

Customer: NV Energy • Las Vegas, NV

NVEnergyNV Energy, Inc. provides electricity and natural gas to more than two million customers throughout Nevada and parts of California. The company’s service area covers approximately 54,500 square miles.

Challenge

The Edward W. Clark Generating Station, dating back to 1954, is the oldest steam-generated power plant in Nevada. Today, it is a multi-technology natural gas-fueled power-generating complex that includes a total of 19 gas-fired Pratt & Whitney turbines with Selective Catalytic Reduction (SCR) exhaust systems. The station is located just a few miles from the Las Vegas Strip and supplies much of the power for the city.

FlexCom was tasked with developing custom fabric expansion joints that could address several challenges:

  • internal operating temperatures of more than 900°F;
  • sudden and powerful rise in temperature in a very short period of time, putting great stress on equipment, compensation joints and connected pipes;
  • particulate contamination in the exhaust flow;
  • noise pollution generated by high vibration plant operations;
  • keeping the joint’s external skin temperature to within Occupational Safety and Health Administration (OSHA) requirements.

Solution

Based on NV Energy’s specifications, FlexCom designed and built composite fabric expansion joints to address all design requirements:

  • Frames were made from A387 chrome molybdenum steel composite, a custom alloy that provides high temperature and thermal shock resistance;
  • ChemShield®, a composite material made from polytetrafluoroethylene (PTFE) thermoplastic film laminated to a PTFE-coated fiberglass cloth, provided excellent temperature and pressure tolerance and a surface that is inert to nearly all chemicals and solvents;
  • Ceramic fabric accumulation pillows ensured superior abrasion resistance and reduced exterior temperatures;
  • Vinyl joint covers further reduced exhaust noise and joint surface temperature.  

When you have a demanding application, turn to the professionals at FlexCom for all your custom industrial expansion joint needs.

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Air Liquide Case Study

Customer: Air Liquide Inc. • Houston, TX

AirLiquidejpgAir Liquide Inc., located in 80 countries, is a world leader in gases, technologies and services for industry and health. Air Liquide has more than 5,000 U.S. employees, over 200 locations including more than 140 industrial gas plants and approximately 2,000 miles of pipeline.

Challenge

Air Liquide’s Hydrogen Manufacturing Facilities in El Segundo, California and Pasadena, Texas, are the first of their kind to be built in the United States. Each is designed to create up to 90 million cubic feet of hydrogen per day, used to supply nearby oil refineries. Air Liquide turned to FlexCom for a variety of industrial expansion joints, in sizes up to 25 feet in diameter and capable of compensating for regular steam exhaust above 1000°F.

Solution

FlexCom designed and fabricated close to 80 percent of the industrial expansion joints in Air Liquide’s hydrogen plants in El Segundo and Pasadena, including flexible fabric expansion joints and composite fabric expansion joints.

  • Flexible fabric expansion joints provided a cost effective, low maintenance solution. These fabric-only joints are relatively lightweight and easy to install. They are constructed of ChemShield®, a Teflon®-coated, high strength fiberglass cloth that is laminated to a sheet of pure Teflon, providing necessary heat tolerance.
  • Composite fabric expansion joints were built for larger outlets, measuring 25-feet by 13-feet. With the same protective features of the flexible fabric expansion joints, the composite fabric expansion joints have heavy-duty stainless steel frames for additional structural integrity.

Turn to the professionals at FlexCom for all your custom industrial expansion joint needs. We provide cost-effective, reliable solutions for even the most challenging environments. 

Connect with FlexCom.

Contact Us Today »  Get a Quote »

Custom Fabric Expansion Joints

FlexCom’s composite fabric expansion joints tolerate heat stresses and pressure loads and provide movement compensation. Our flexible fabric expansion joints are a lightweight, economical option for low pressure and moderate heat applications.

About Fabric Expansion Joints »

Metal Bellows

FlexCom’s custom metal bellows are made from high quality alloys and handle pressure up to 300 psi, temperature loads up to 2500°F and the transfer of liquids through joints and surrounding piping.

About Metal Bellows »

When Connections Matter, FlexCom Delivers

6864 Chrisphalt Drive • Bath, PA 18014 • 888-376-FLEX • 610-837-3812 • sales@flexcomonline.com