Validation of External Corrosion Growth-Rate Using Polarization Resistance and Soil Properties

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• Onshore Transmission Pipeline
• Gas Pipeline
• Liquid Pipeline
• External Corrosion

Main Objective

The objective is to estimate corrosion growth-rates, reduce assessment costs, and improve the selection of reassessment intervals of pipelines and increase their safety. This will be achieved by: (1) perform field tests and demonstrations using LPR and ER technologies, (2) correlate results with weight-loss of buried coupons, (3) evaluate soil parameters that affect corrosion, and (4) incorporate the measurements into a database and program that improves corrosion-rate estimates.

Public Abstract

External corrosion growth-rate is an essential parameter to establish the time interval between successive pipe integrity evaluations. Actual corrosion rates are difficult to measure or predict. NACE Standard RP0502 for Direct Assessment (DA) of transmission pipelines recommends several methods including comparison with historical data, buried coupons, electrical resistance (ER), and Linear Polarization Resistance (LPR) measurements. This research establishes a testing program and procedure to implement and validate LPR and ER methods for the DA of external corrosion of gas pipes.
The objective of this research is to enhance the estimation of corrosion growth-rates, reduce the assessment costs, and ultimately, improve the selection of reassessment intervals of gas pipelines and increase their safety. This will be achieved by: (1) performing field tests and demonstrations to promote the use of LPR and ER technologies by gas utilities, (2) correlate the results with other measurement methods, (3) evaluate soil parameters that affect localized corrosion, and (4) incorporate the measurements in a database program that improves corrosion-rate estimates with the increasing number of soil data and corrosion measurements.