Reinforced-Concrete Chimneys
for Industrial Plants

For reinforced-concrete industrial chimneys, internal diameter and height are determined by the process gas, draught requirements and the structural model. Typical production ranges cover internal diameters of several metres and heights of several tens of metres; taller chimneys can also be built with dedicated calculations and a slipform programme. Wind, seismic action, temperature differentials and maintenance access all influence the cross-section. Final dimensions are not fixed until the site survey, emission line and structural calculations are complete. At handover, verticality, levels and platform access are recorded.

On taller chimneys, wind-induced vibration and maintenance platform loads increase the required cross-section. Internal diameter alone is not enough at the survey stage; existing neighbouring units and the gas duct are also assessed. Formwork fabrication is not committed until structural approval has been received.

Yes. The key at an operating plant is to open safe installation windows without stopping the production line unnecessarily. OHS, crane corridors, lifelines and the shift pattern are established together with the plant operator. Slipform or steelwork is sequenced so that it does not clash with the gas line or with maintenance shutdowns. Measurement platforms, ladders and embedded connections are installed as the shell rises, reducing the need for subsequent breaking-out and rework.

At an operating plant, a shift change never resets the work: completed guardrails and lifelines are handed over to the next crew. Hot work permits are renewed daily. If the programme conflicts with the control room's shutdown schedule, fabrication is put on hold.

Continuous emission monitoring points should be resolved within the same design as the chimney shell. If port levels, platform width, ladder access and electrical routing are added later, both tightness and occupational safety are compromised. Measurement balconies, lighting and cable routes are therefore built into the slipform or steel erection programme. At handover, the operator can see the sampling and maintenance levels in the report. In this way, regulation-compliant access becomes an integral part of the structure.

If a sampling port is cut afterwards, both tightness and sample quality suffer. Platform width is selected according to the load of instruments and personnel. Cabling is never embedded randomly in chimney joints; it runs down a dedicated cable route.

Lining and concrete class are determined by process temperature, gas composition and corrosion risk. On high-temperature lines thermal expansion is the priority, while with acidic gases chemical resistance comes to the fore. Internal coatings, joint details and levels requiring maintenance access are marked during the site survey. Material selection is not just about catalogue values; it goes hand in hand with the site pouring regime and setting control. The right lining has a direct effect on the chimney's service life and maintenance frequency.

Lining trials do not end with a laboratory label; setting and surface moisture are also monitored during site pours. The wrong coating can flake away within a few seasons. The handover notes record the maintenance levels and how coating renewal is to be carried out.