With the experience gained from many inspections in both the North Sea and the Gulf of Mexico, GUL’s Sub-Sea GWT equipment has evolved into a reliable modular system. GUL Sub-Sea rings are easily adjusted to fit different pipe sizes and are available for both ROV or diver deployment.

The advantages of using the Sub-Sea rings include:

• Screening unpiggable sections of line for internal or external corrosion/erosion.
• Screening under weight coat and insulation with minimal cleaning and excavation.
• The on-site analysis allows the ROV to perform follow-up indications.

First developed in 2005 with the assistance of Network Rail, the G-Scan rail instrument sends guided waves down the length of a rail to look for any areas of cross section change. The guided waves that are created in the rail are able to detect cracks and corrosion in any section of the rail, including the ‘foot’ and ‘toe’.

Because of this ability to detect corrosion areas that are normally hidden from higher frequency methods that access the rail from the head, the G-Scan system is often used to inspect level crossings that are susceptible to foot corrosion, but are difficult to inspect without disrupting both rail and road traffic. Guided wave inspection performed from outside of the level crossing can inspect the section while the road is still fully operational; rail traffic is often not disturbed if the period between trains is long enough. The results allow you to rank the crossings, extending the mandatory lifting time for some crossings, prioritising replacement for others.