SVI BREMCO has experience and in-house capabilities to design steel stacks to meet any structural and aerodynamic project performance requirements.  Steel stacks can come in varying sizes and wall construction depending on the properties of the gas turbine exhausting into them.  A steel stack for gas turbine exhaust can be a single wall or internally lined depending on temperatures.

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SVI BREMCO is an industrial equipment supplier that provides HRSG exhaust and free standing stacks

There are three types of stacks for gas turbine applications that SVI BREMCO can help with:

  • Simple cycle – simple cycle stacks involve hotter temperatures and more turbulent flow because there is usually nothing upstream in the gas path to help improve flow like in an HRSG.
  • Bypass – a bypass is very similar to a simple cycle but in fact the flow coming into a bypass stack can have worse aerodynamics as the transition from horizontal to the vertical stack is usually from the blunt 90 degree angle off a diverter damper.
  • HRSG (main) stack – these stacks are exposed to the most mild conditions for gas turbine exhaust because the HRSG has already drastically improved the exhaust flow and has significantly reduced the temperature of the exhaust gas. In fact most HRSG main stacks are fabricated using unlined carbon steel because the temperatures are in the 300-400F range which is an acceptable temperature for carbon steel even for prolonged periods.

Typical example design codes for stack engineering

Building design codes:

  • International Building Code (IBC)
  • American Society of Civil Engineering- Minimum design loads (ASCE7-10)
  • State or Local Building Codes as required by project specification

Structural Design Codes:

  • AISC Manuals and Codes (structural design, Seismic design, etc.)
  • STS-1 (steel stack)
  • ASME II- part D (material properties)
  • American Welding Society codes (AWS)
  • ASCE publications

Typical stack components and accessories include:

  • Ladders and platforms
  • Test and CEMS ports
  • Aviation lighting
  • Access doors
  • Stack dampers
  • Free standing or support tower
  • Vortex shedding (tuned mass damper or helical strakes)
  • Floor drain
  • Silencer
  • Lightning protection

Given the height of an exhaust stack and the loads that can impact the design, reliability is extremely important.  An exhaust stack has to be designed to remain safe and this can be challenging especially as they can be over one hundred feet tall.  SVI BREMCO uses FEA (finite element analysis) to review all structural design aspects of stack design.  Stack design guidelines  are provided for uniform geometries, but in gas turbine exhaust stacks it is not uncommon to have a stack that is non-uniform.  Most of the time the irregular geometries in a turbine exhaust stack are from the accommodation for an exhaust silencer design.  Some exhaust silencers are in the upstream horizontal ductwork before the stack breech.  However a lot of power islands do not have enough space to accommodate a silencer in the horizontal duct and/or it is more economical to put the silencer in the vertical stack.  However a stack sized for reasonable exhaust velocities may not be a large enough cross section to accommodate the needed silencing.  Therefore the stack design will incorporate a larger gas path that can be either round to round or square to round to be sure an appropriate silencer design can be incorporated.  Given all of this, SVI BREMCO routinely uses FEA analysis to confirm the structural design for the steel exhaust stacks.

Ensuring the reliability and efficiency of your free-standing exhaust stacks is critical to operational success, regulatory compliance, and long-term cost savings. A well-maintained bypass stack in your power plant ensures uninterrupted operations by providing an alternative exhaust route when the primary system, such as an HRSG stack (Heat Recovery Steam Generator stack), is offline for maintenance or repairs. To prolong the lifespan of your stacks, it’s essential to implement regular inspections for corrosion, thermal expansion damage, and structural integrity, conduct non-destructive testing (NDT) for hidden defects, and schedule cleaning to prevent buildup that can impact airflow and efficiency.

To effectively assess the design quality of your existing stacks, evaluate factors such as material selection, structural integrity, thermal resistance, and compliance with environmental and safety regulations. A well-designed engineered exhaust stack should efficiently handle temperature fluctuations, resist corrosion, and adequately distribute emissions. If your stacks show excessive vibration, cracks, misalignment, or declining efficiency, it may be time for an upgrade or retrofit.

When choosing a specialist for exhaust system design and maintenance, look for expertise in industrial exhaust stacks, proven experience with HRSG stack systems, and a track record of successful stack exhaust repairs and retrofits. Key criteria include certifications, compliance knowledge, engineering capabilities, access to advanced inspection technology, and a commitment to long-term maintenance support. By partnering with the right experts, you can extend the lifespan of your stack exhaust systems, maintain regulatory compliance, and avoid unexpected shutdowns that disrupt power generation.

Download our Stack Inspection Checklist from SVI BREMCO'S Experts

We’ve developed a stack inspection checklist to help you identify problems before they lead to plant downtime. There are several good reasons to inspect your stack:

  • Do you want to prevent downtime?
  • Have you noticed significant degradation of any structural component?
  • Has your stack experienced an unusual event such as an explosion, earthquake, fire or overheating?

Knowing what you should inspect annually and every three years saves you time, money, and stress.

Download our Stack Inspection Checklist

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