Top-of-line spatial corrosion prediction in gas pipelines

The top-of-line corrosion (TLC) is corrosion observed at the upper section of a pipeline, as measured from the circumference of the pipe. The magnitude of TLC is mostly determined using the mechanistic condensation models. The spatial prediction of TLC, however, has not been of the interest among researchers, so as to know at what o'clock orientations (with respect to pipeline cross section) corrosion may accumulate the most. TLC spatial prediction is directly related to the release of corrosion inhibitor (CI) in the pipeline. The probability of retaining CI at the upper part of the pipeline is always a challenge due to the inconsistency of the operational flow parameters coupled by acceleration due to gravity. Thus, there is the need to properly understand the development of TLC with regard to its space. This paper proposes the analysis on TLC spatial prediction to be carried out by means of statistical approaches called the Exploratory Data Analysis (EDA) due to the nature of corrosion that are random. EDA is a simple tool that is able to summarize the main characteristics of TLC data using visual methods. The TLC data was taken from a gas pipeline operating in Malaysian offshore region. A median polish model (of EDA) for the TLC was later generated. A prediction table was also developed to guide users on the estimate of TLC in gas pipelines with regards to the o'clock orientations of the pipe circumference. Copyright © 2014 by ASME.