This code covers the structural aspects of designing and constructing steel chimneys, both self-supporting and guyed. It provides comprehensive guidelines on materials, load calculations (wind, seismic, thermal), and the design of the chimney shell, lining, base plates, and foundations. The standard also addresses critical serviceability issues like deflection limits and vibrations induced by wind.
Code of practice for design and construction of steel chimneys, Part 2: Structural aspects
Quick Reference Values
Minimum shell thickness for self-supporting chimney6 mm
Minimum shell thickness for guyed chimney5 mm
Minimum corrosion allowance (unprotected)1.5 mm
Permissible tensile stress for IS 2062 Gr A steel150 MPa
Minimum thickness for base plates20 mm
Minimum diameter of lightning conductor (Copper)20 mm
Minimum diameter of lightning conductor (GI)25 mm
Key Formulas
f_combined = (W/A) + (M/Z) — Combined stress due to axial load and bending moment
Vb = C * αh * W — Seismic base shear
T = C_T * H^2 / (D * sqrt(t/ρ)) — Fundamental period of vibration of chimney
Vcr = fD^2 / (H * St) — Critical wind speed for vortex shedding
Practical Notes
This standard (Part 1) focuses on mechanical details and must be read in conjunction with IS 6533 (Part 2), which covers the structural design and analysis for loads like wind and earthquake.
Corrosion allowance is a critical parameter not explicitly defined for all cases; it must be determined by the engineer based on flue gas characteristics, operating temperature, and expected service life.
The code specifically excludes the design of refractory linings but requires their weight to be considered in the overall design.