Industrial Chimney
An Industrial
100-foot (approx. 30 Meters) MS (Mild Steel) Chimney is a significant
structural installation. At this height, the chimney must be designed as a self-supporting
cantilever structure or a guy-wire supported stack to withstand high wind loads
and seismic forces.
In India, these are
fabricated according to IS-6533 (Code of Practice for Design and Construction
of Steel Chimneys).
1. Typical
Structural Specifications (100ft)
|
Component |
Specifications |
|
Height |
100 Feet (30.48
Meters) |
|
Shape |
Cylindrical with
a Flared (Conical) Base |
|
Inner Diameter |
600 mm to 1200 mm
(depending on flue gas volume) |
|
Base Diameter |
Typically 1.5 to
2 times the stack diameter (for stability) |
|
Plate Thickness |
Bottom: 10mm to
12mm | Top: 6mm to 8mm |
|
Material Grade |
IS 2062 Grade B
(Mild Steel) |
|
Mounting Type |
Foundation/Island
Mounted (Self-Supporting) |
2. Design &
Engineering Details
- The Flared Base: For a 100ft chimney, the
bottom 1/3rd (approx. 33 feet) is often flared out. This provides a wider
footprint for the anchor bolts and prevents the chimney from swaying
excessively.
- Wind Load Management: At 100 feet, wind is
the primary "enemy." The structure is designed to handle wind
speeds up to 150-180 km/hr (depending on your zone in Gujarat).
- Corrosion Allowance: Since flue gases are
acidic and the stack is exposed to rain, an extra 1.5mm to 2mm is added to
the calculated thickness as a "corrosion allowance" to ensure a
10–15 year lifespan.
- Internal Lining (Optional): If you are
venting high-temperature boiler gases 250 C the
bottom half is usually lined with refractory fire bricks or acid-resistant
glass wool to protect the MS shell from heat and chemical erosion.
3. Essential
Accessories
- Lightning Arrestor: A copper spike at the
top connected to a dedicated earth pit is mandatory for a 100ft structure.
- Aviation Warning Light: Due to the height,
a twin-lamp LED red light must be installed at the top for aircraft
safety.
- Ladder & Platform: An MS monkey ladder
with a safety cage and a sampling platform (at about 70-80 ft) for
pollution board testing.
- Sampling Port: A 3-inch or 4-inch nozzle
with a cap for the GPCB (Gujarat Pollution Control Board) to measure
emission levels.
4. Foundation
Requirements
A 100ft MS chimney
cannot be placed on a standard floor. It requires a RCC (Reinforced Cement
Concrete) Pedestal Foundation.
- Depth: Usually 8 to 12 feet deep.
- Base Plate: A heavy MS plate (25mm to 40mm
thick) is welded to the bottom of the chimney and fixed to the foundation
using High-Tensile J-Bolts.
