Common deposits and their influence on corrosion in the pulp and paper industry

Deposits commonly encountered throughout the Pulp and Paper Industry are generally classified as microbial or non-microbial. Both of these categories can be further subdivided into a variety of classes, within which all common deposits can be placed. Despite the variety of deposits encountered, the corrosion problems posed by the presence of the deposits are few. Quite simply, environments beneath deposits promote localized attack, i.e. under-deposit attack. General corrosion can also be promoted by the chemicals and procedures used to remove the deposits from equipment and piping systems. The production of bleached paper is-traced from the wood yard through the paper machine. This discussion is limited to the deposits commonly found in the equipment and piping directly in contact with the chips and fiber. Generic guidelines for the control of these deposits are discussed, along with the impact of process changes on deposit production.