WALL THICKNESS MONITORING OF NEW AND EXISTING SUBSEA PIPELINES USING ULTRASOUND

摘要

Ultrasonics is a safe and reliable method for inspection and monitoring. The most common application of ultrasound in NDT is probably to measure the wall thickness, where the method gives a direct and quantitative result. If ultrasonic sensors are installed permanently, more accurate monitoring is possible, because the error and uncertainty associated with operator and exact measurement position is removed. The current paper describes a system where ultrasonic monitoring is carried out by using an instrumented clamp. Contactless immersion ultrasound is used, which allows for this system to be retrofitted on existing subsea pipelines. The paper describes lab experiments which indicate that this instrumentation can be used to estimate annual corrosion rate with an accuracy of 0.1mm per year within a short period (days).