The Case for Caisson Inspection with Teletest Focus™

Paul Jackson

General Manager - Teletest

Originally designed for detecting corrosion under insulation in petrochemical plant pipework, guided wave testing (GWT) with the Teletest Focus™ has found widespread use in a wide range of applications where pipelines or tubes are not easily accessible.

Teletest is a long-range ultrasonic testing (LRUT) or GWT technique deployed for locating metal loss. Employing a pulse-echo system designed for testing large volumes of material from a single test point, it is the superior candidate for pipelines that are buried, encased in a sleeve or elevated aboveground.

Given this novel capability, the Focus+ instrument was deployed in a field trial to inspect caissons on an offshore installation. Direct access is typically difficult, but the Focus was able to inspect the entire length of the caisson from the topside. The purpose for this assessment was to determine the caisson’s condition prior to removal. Using both torsional and longitudinal wave modes, the Focus used Multimode Modules to get complete data results (check out this blog on why two modes are better than one). In this case, torsional was the ideal testing condition given the wall thickness of the caisson.


The following data results indicate the end of the caisson, located 65 meters (213 feet) away, to be in reasonable condition. An increased area of corrosion identified 32 to 35 meters (105 to 115 feet) down the caisson correspond with the splash zone. Within the software an A-map can be produced instantaneously for all frequencies, providing valuable information about circumferential extent to the technician. In this example, the operator could see that the worst area of corrosion in the splash zone was still within the acceptable limits.



When it comes to the examination of offshore and subsea assets like pipelines, risers and caissons, Eddyfi Technologies rises to the most complex industry challenges. The proven Focus+ unit offers the reliability and versatility operators should expect. Why not discuss your long-range ultrasonic testing requirements with us and stay Beyond Current?

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