The majority of Air Pollution Control Systems employ wet scrubbing technology for the removal and neutralisation of acidic products emitted on the combustion of fossil fuels and the incineration of waste materials, prior to discharge of the flue* gases from a chimney or stack** to the atmosphere. Discharge of wet gases from a scrubber at or below dewpoint results in the formation of condensates. In addition to the formation of highly corrosive sulfuric acid in the clean gas stream, hydrochloric and hydrofluoric acids may be present to a greater or lesser degree. High alloy stainless steels and nickel base alloys are increasingly specified for the linings of the clean gas handling conduit, comprising ducts, gas turning devices, flues and dampers to change direction of flow or for isolation. Application of intrinsically expensive materials in appropriate forms permits cost-effective utilisation,
particularly when Life Cycle Cost criteria are taken into consideration.
Keywords: nickel alloys, nickel stainless steels, metallic linings, critical corrosion conditions,flue gas treatment, pollution control, wallpapering, clad plate, dew point, dewpoint corrosion, fabrication, chimney costs, life cycle costing, residual value, chimney, stack, flue.