INTRODUCTION

ABSTRACT

Corrosion costs the Oil and Gas industries alone billions of dollars annually in downtime, production loss, equipment failures, environmental contamination and most importantly personnel injuries and fatalities. Many of these corrosion related costs could be significantly reduced by endorsing the use of continuous corrosion monitoring technologies as part of a plant comprehensive corrosion management program.

In the last few years, there has been an increasing demand for online corrosion and/or erosion monitoring tools for monitoring wall thickness measurements on pipelines and process equipment. Corrosion-related failures can be significantly minimized if a rigorous corrosion monitoring and inspection program, including predictive maintenance and real-time monitoring tools, are in place. Utilizing a non-intrusive approach will provide flexibility in selecting the monitored locations in non-accessible or congested areas where intrusive devices may not have room to function.

This paper will address a field assessment program conducted recently on a new non-intrusive multi-sensor corrosion monitoring tool. The evaluated technology is based on Acoustic Guided Lamb Waves (AGLW). The objectives of this field assessment were to identify the applicability and limitations of this technology. Based on the obtained data, the system was able to report the wall thinning changes and validate its functionality.

The increased demand for oil, gas, and refined products has resulted in a vast transportation network of pipelines. Monitoring these pipelines can prove difficult, expensive, and time consuming with limited results using common nondestructive testing (NDT) techniques1. The current corrosion monitoring practice within the industry is to install intrusive probes or coupons as a tool to evaluate and monitor fluid corrosivity. Intrusive corrosion monitoring probes or coupons are costly, labor-intensive, and do not provide timely warning. In addition, they cannot reflect what is happing on the monitored pipe. Some oil and gas operation companies do not prefer installation of intrusive probes in their transmission lines which are equipped with scraping facilities2. Such a decision has elevated the need to have non-intrusive tools to maintain their network integrities.

Online corrosion monitoring is an important component of any comprehensive corrosion control program. It enables the operators to detect changes in corrosion behavior, enable timely remedial action to be taken, eliminate unplanned plant shutdowns, diagnose a particular corrosion problem, correlate the effect of changes in process parameters on system corrosion, assess the effectiveness of the ongoing treatment chemicals program, and to increase the lifespan of the equipment2.

Acoustic measurements based on guided wave techniques are attractive tools for pipeline integrity monitoring. A field program to assess an available non-intrusive technology was therefore launched. The proposed system is a non-intrusive device that enables continuous measurement of corrosion or erosion damage across a large area on equipment. The program objectives were to study the functionality and limitations of the newly introduced system on reporting wall thinning in real time. Utilizing a non-intrusive approach will provide flexibility in selecting the monitoring locations in congested areas where intrusive devices may not have room to function3.

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