This TIP is a review of general considerations related to UT thickness testing of black liquor recovery boiler tubes:

Part I of this TIP provides guidelines and procedures for acquiring accurate ultrasonic thickness readings on boiler tubes, where the tube material and condition are conducive to such non-destructive thickness testing.

Part II describes how tube thickness surveys are commonly laid out for different zones of a typical recovery boiler. It also stresses that a customized survey is essential for each boiler.