ABSTRACT
Non-intrusive continuous wall thickness monitoring systems are fast becoming industry best practice for online detection and monitoring of corrosion and erosion. Challenges with localized corrosion have been knowing where to deploy online monitoring sensors and also being able to quickly and easily interpret the data that is delivered.
The authors will demonstrate that deploying only a modest number of point measurement devices in an area of elevated localized corrosion risk will provide the best possible combination of probability of detection (POD) as well as ongoing wall thickness monitoring for localized corrosion attack.
Recent advances in ultrasonic signal processing that takes advantage of specific historic data that is recorded by the online wireless wall-thickness monitoring system has been instrumental in separating the effects of wall-thickness loss from changes to internal surface morphology at the measurement locations. These advances make the data from the online monitoring system considerably easier to understand and interpret when the corrosion mechanism that is occurring is creating a rough internal surface at the measurement location - i.e., as per many localized corrosion mechanisms. Specific field examples from the ~10,000 installed sensors worldwide are presented to demonstrate the improvements of the new signal processing technique.
INTRODUCTION
Part A: Reliable Detection of Localized Corrosion
The purpose of online integrity monitoring is to enhance the operational performance of an asset through improved decision making whilst the equipment is live; avoiding loss of containment whilst maximising asset productivity. This is achieved through a combination of:
Early detection of corrosion or erosion events, before the risk of loss of containment is too great for remedial action to avoid loss of containment.
Monitoring of the severity of corrosion or erosion, measuring the integrity of the equipment in real time and helping determine the root cause of corrosion or erosion.
Optimization of any required corrosion mitigation strategy based on above insights, thereby optimizing asset performance.
Validation of corrosion or erosion mitigation strategy continues to adequately control corrosion or erosion, while maximizing the operational performance of the asset.
