EMAT for detection of axially aligned cracks at girth welds
This paper outlines the work of collaboration with a Western Europe gas pipeline operator and a service company to explore the performance of the PII’s EMAT crack inspection technology to detect axially aligned cracking in the vicinity of girth welds. The operator has reason to believe cracking at the girth weld may exist in their pipelines or may occur in the future, based on the confirmed existence of such cracking in other operator’s pipelines with similar construction and service histories and that are geographically close. The utilization of conventional ultrasonic inline inspection tools, which need to be surrounded by liquid coupling, is a difficult operational challenge in a pipeline that normally carries gas. The EMAT vehicle does not need a liquid couplant but has an area on either side of the girth weld where the detection performance is influenced by the lift-off behaviour of the sensors. The EMAT inspection performance in the vicinity of girth welds has been investigated and the results are summarized in this paper.