Corrosion Under Insulation (CUI) of insulated pipelines and leakage or intrusion detection on underground utility pipelines are two applications where Distributed Fiber Optic Sensing (DFOS) provides a promising alternative to existing monitoring techniques. In this paper, we present case studies for both domains.

When Distributed Acoustic Sensing (DAS) is used in combination with Distributed Temperature Sensing (DTS) to monitor corrosion under insulation (CUI) risk in the chemical industry, a fiber optic cable is attached to the outer cladding of the insulated pipeline. This offers the big advantage that the insulation or cladding does not need to be dismantled to install the monitoring system. The monitoring system CUI-CONTROL was specifically developed this way.

On the other hand, detecting leaks and third-party intrusions (TPIs) in underground pipelines can be done by placing a fiber optic cable inside the pipe. This allows existing pipelines to be retrofitted without new trenching, and leak sounds are detected without concerns about the relative positioning between fiber and leak. With that in mind, DALI (Distributed Acoustics for Leakage and Intrusions) was developed, which is highly suited for retrofitting utility, steam, oil and gas pipelines.