Determination of depths of corrosion pits in pipes associated with deposit by radiography

Pipings and pipelines are vulnerable to internal and external corrosion and subjected to deposit accumulation because of chemical effects. Determining the extend and progress rate of corrosion and deposit provides useful information about the operational life and safety of the equipments and plants. The condition of pipings and pipelines can be monitored by the proper use of non-destructive inspection methods even while the plant is in operation. Pitting is a special kind of corrosion, which is very often encountered in pipes. Detection of corrosion pits in pipes can easily be performed by using tangential radiographic and film density measurement methods. Detection of pits, which are associated with deposit can not be directly performed by density measurement method and requires special simulations. This study describes the determination of depths of pits in pipes associated with deposit by radiographic density measurement method. Special simulations were made in order to obtain density-deposit thickness reference curves for the evaluation of deposit thickness and thus pit depth. Difficulties and limitations of the method were discussed