April 7, 2025 · Power Plant · ShaktiPunj
Boilers, kilns and furnaces all need a chimney to discharge cleaned flue gas high enough for it to disperse safely. Self-supporting steel chimneys are a common choice for industrial plants because they are quicker to build than concrete stacks and can be fabricated in sections.
Deciding the height and diameter
The chimney height is set by the pollution control board's requirements and dispersion needs, not only by the draught. The diameter follows from the flue gas volume and the exit velocity needed to carry the plume clear of the plant.
Structural design
- Wind load, including the vortex shedding that can make tall stacks oscillate
- Seismic load as per the site's earthquake zone
- Thermal stresses from hot flue gas
- Openings for the flue duct, sampling ports and access doors
Helical strakes or dampers are added where the analysis shows a risk of wind-induced vibration.
Foundation and anchor bolts
The foundation carries large overturning moments. Anchor bolts are set accurately with templates before the concrete is poured, because a misaligned bolt circle delays erection and is costly to correct.
Protecting against corrosion
Flue gas can condense on cooler steel surfaces and form acids. Insulation, suitable internal coatings or liners, and a good external paint system extend the life of the chimney considerably.
Erection on site
- Fabricated shells are checked for dimensions and welding quality before dispatch
- The base section is set, levelled and grouted
- Upper sections are lifted with suitably rated cranes and joined by bolting or welding
- Verticality is checked at every stage
- Ladders, platforms, aviation lights and lightning protection are fitted
Every lift follows an approved lifting plan, with the area barricaded and work stopped in high wind. ShaktiPunj prepares chimney designs, fabrication drawings and erection procedures, and supervises the work on site.