Management of modification of new heat recuperator system / Rahimi Ngah

The heat recuperator has been affecting the continuous operation of the Perwaja Direct Reduction Plant. The problems of heat recuperator are tubes crack, clogging at top of hot exhaust inlet gas and at bottom cold outlet gas. Intergranular corrosion and stress corrosion cracking are problems associated with the use of stainless steel and must be considered when selecting types suitable for use in process environment. The stress corrosion cracking of stainless steels can be caused by a few ppm (part per million) of chloride ions. Stress corrosion cracking can be avoided by selecting materials that are not susceptible in the specific corrosion environment. The life of equipment that prone to corrosive environment can be prolonged by proper design. Many factors have to be considered when selecting engineering materials, but for chemical process plant the overriding consideration is usually the ability to resist corrosion. The most economical material that satisfies both process and mechanical requirements should be selected, this will be the material that gives the lowest cost over the working life of the plant allowing for maintenance and replacement.