Caisson Guide – Cleaning, Inspection and Centraliser Installation
Tool Tec were approached in 2020 by one of its key customers to carry out the installation of new centralisers into two of their conductor guide funnels to support both a 42″ and 20″ diameter caisson. From ROV survey footage it was clear that the previous centralisers had failed and were no longer providing any support, however, some of the supporting structure and locating bolts were still in place, potentially causing issues for the installation of the new centralisers.
With the use of the 36″ Cleaning and Inspection Tool c/w Extension Arm Module, Tool Tec were able to initially travel down one of the adjacent conductors and carry out cleaning of the caisson and guide funnel, using the manipulator held mechanical and HP waterjetting cleaning tools. Once the area was thoroughly cleaned, the manipulator was armed with a laser measuring tool to carry out a survey of the area, the data from which was compiled into a formal report providing the precise location of the caissons within their guides and any obstacles present.
Tool Tec’s engineering team were then able to use this data to design and manufacture a bespoke centraliser solution for use within both of the guide funnels. A trial fit using a mock-up guide funnel was carried out onshore, before the offshore team went back out and fitted each of the centralisers with the use of the manipulator on the 36″ Cleaning and Inspection Tool. Finally, an as-left survey was carried out by the Tool Tec mini-ROV as a final check, prior to the demobilisation of personnel and equipment.
The Pipeline Technical Authority on the project commented “We really appreciate the efforts of all the Tool Tec team involved. Tool Tec were able to carry out the full scope from concept, detailed design, manufacture, testing and installation – and the fact that the new centralisers were installed quickly with no problems, is testament to the hard work and knowledge of the Tool Tec team”
BEFORE – Extension Arm trials being carried out onshore with mock up conductor layout
BEFORE – Centraliser (or shims) fitted within test / transportation frame
AFTER – Extension Arm carrying out laser inspecting on an adjacent caisson
AFTER – centralisers successfully installed offshore