Abstract
The reasons for which the field data is generally collected, the accuracy of the field data versus requirements of model validations, and the reasons why model validations were unsuccessful were explained in detail in the 2006 version of this paper. It was also mentioned that the lack of knowledge about possible impact of some important parameters, like small amount of H2S and organic acids, on the corrosion rate makes the interpretation of the data often questionable. Other discussed issues were the mechanism of localized corrosion and calculation of the corrosion rate based on inspection and monitoring. Since 2006, no significant changes were reported and the conclusions of the 2006 paper are still valid. However, during the last 10 years the top of the line corrosion (TLC) became an important issue and this aspect was not covered by the 2006 paper. The present paper is dedicated to this subject. As there was neither TLC prediction model available on the market and nor published field experience on the subject, the author company decided to collect very detailed field data from different pipelines and fields. The collected field data was carefully analyzed and possible mechanisms were identified and confirmed by laboratory experiments. Influences of different parameters were experimentally confirmed as well. Finally, validated field data was extensively used for corrosivity prediction, corrosion control and even for the design of new pipelines. The data collection and analysis process lasted more than a decade until full mechanism is understood and validated, main parameters are fully identified and a reliable prediction model is available. The paper describes in details the way the field data is collected, analyzed, validated and used for different purposes mentioned above.
