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Gas Turbine Exhaust Systems

DESIGN PRACTICE, OLD GENERATION GAS TURBINE EXHAUST SYSTEMS

Early generation offshore installed exhaust systems were typically designed with external thermal insulation, in combination with ducting fabricated in Austenitic Stainless Steel, and unfortunate combinations of material thicknesses and welding practice.As result, early generation systems are suffering from operational wear like extensive crack damages, leaking flanges, and degraded thermal insulation.Installations have in many cases been considered beyond repair and decided retrofitted.

As of today, operators realize that retrofit installation may not be practical and economic, due to high CAPEX and production loss during unit retrofit period.

NOBLE INSTALLATION EXHAUST SYSTEM EXTENDED LIFE™

Noble Installation has developed and patented proven upgrading products and methods extending the exhaust system life with more than 500 start/stop cycles, typically accumulating to 20 years extended operational life.

The extended life upgrade includes field activities without use of hot work, and by applying Noble Installation patented and proven methods and products

NOBLE INSTALLATION PROVEN PRODUCTS AND METHODS

Over the past 8 years, Noble Installation has focused on development of products and methods to
extend the life of old generation exhaust systems.

The designs are based on own inhouse technology, by personnel with up to 50 year experience in
engineering, manufacturing, testing and field servicing of Gas Turbine Packages.

The Life Extension Designs are made in compliance with OEM requirements and general Codes &
Standards, and in compliance with customer requirements.

The following is a brief presentation of our proven products and methods.

HotBolt™:

  • Self-aligning fastener: To allow for bolting of warped and non-parallel flanges.
  • Temperature range: Up to 1050 °C
  • Material selection: B7, Duplex, Super Duplex, Inconel 625, Inconel 718.
  • Dimensions: Metric or imperial, designed for each application.
  • Stress level: Accumulated stress level from HotBolt™ pre-tension and thermal growth in bolted material will not reach Ϭ proof.
HotBolt™ Inconel 625 with locking plates.
HotBolt™ Inconel 625 with locking plates.

HotSeal™ : Gasket for Exhaust System flanges.

  • Jacket material: Silica, reinforced with Inconel wires.
  • Sealer core: Inconel mesh sealer core.
  • Operating temperature: 732°C continuous operating temperature.
  • Resilient properties: Maintained after heat cycle and long-term operation.
  • Flange Spacer strip: Securing correct gasket compression and a stiff bolt connection.
HotSeal™ Gasket on flange.
HotSeal™ Gasket on flange.

CCRM™. (Crack Cold Repair Method).

Crack damages in exhaust system typically develops after few years of operation, depending on material selection, operational loads, and number of transient operations.

Typically, tempts are made to repair weld crack damages.
However, repair welding of crack damages has a limited life, and the cracks typically develop further after only few Start / Stop Cycles.

Noble Installation has developed the method CCRM™ for repair of crack damages, without use of hot work.

The CCRM has been applied on several Gas Turbine Exhaust Systems and has proven to extend the life with 500 Start/ Stop Cycles.

CCRM™¨Corner reinforcement profile EXHAUST SYSTEM EXPANSION BELOW.

General expansion bellows may have a limited life, and under unwanted conditions, yearly replacement may be needed. Noble Installation has in cooperation with LBH International in Denmark developed an Extended Life Expansion Bellow.

AlphaFlex™ Expansion Bellow is manufactured and field installed by Noble Installation AS.

  • AlphaFlex™: Design life is 600 Start / Stop Cycles.
  • AlphaFlex™: Offered with 4 years operational guarantee.


EXHAUST SYSTEM HOT SPOTS.

Exhaust systems with crack damages and leaking flanges will suffer from external surface hotspots.
Hot spots may also be caused by degraded thermal insulation.
Surface hot spots with elevated temperatures may result in a hazardous situations if exposed to gas.


Noble Installation has developed and qualified a repair method to reduce hot spot temperature
levels.

The method includes use of Noble Installation patented products and methods:

  • HotBolt™ Fasteners.
  • HotSeal™ Flange Gasket.
  • CCRM™ Crack Cold Repair method.
  • AlphaFlex™ Expansion Bellow.
  • Noble Installation-LBH long fiber Ceramic insulation concept.
  • Taylor made insulation pillows and panels.