The trend in crude oil refinery processing in recent years has been toward longer unit operating cycles. This has been largely accomplished by improved design, upgrading equipment metallurgy, onstream inspection, and use of corrosion inhibitors. Increasing run length has added emphasis to the importance of equipment fouling since fouling in many units is now the limiting factor in determining length of operating cycles, rather than metallurgy as in the past. When operating units were shut down on short cycles for maintenance, the equipment was cleaned during the turnaround; consequently, fouling was normally not a serious problem. With operating cycles extended, however, this is no longer true. Case histories presented in this paper demonstrate how antifoulants and corrosion inhibitors have been used to mitigate both fouling and corrosion.
