Directional boring commonly known as Horizontal Directional Drilling (HDD) is a technique widely employed in landfall areas. HDD provides advantages of crossing considerable lengths with local soil disturbance and low environmental impact, which has contributed to turn it into one of the preferred techniques between various authorities.
In despite of these advantages, the corrosion protection of the HDD is complex due to the unfeasibility of installation of sacrificial anodes distributed uniformly along the HDD, which would require a remote protection engineering solution as an alternative. The remote solution adopted, the level of coating damage on the pipeline after the installation, the corrosiveness and resistivity of the surrounding environment, in particular when very different environments encounter, i.e. sea-sand-rock, are major uncertainties that must be considered on the design. In addition, the lack of recommendation on international standards and the difficulties involved with the direct inspection of the pipeline section inside the HDD increases the robustness required for the design and its verification.
This paper presents the corrosion protection system of a gas line section inside a HDD in a landfall area, describing the combination of pipeline coating and cathodic protection systems both specified to resist the service life of the pipeline. After a brief review of published works related to this subject, this paper will focus on the coating and cathodic protection design presenting not only the premises, design data and methodology adopted, but also associated results and installation issues. Computing modeling and recommended practices are used to identify the best and the most feasible solution. Finally, conclusions and recommendations will be presented in order to support future projects with similar challenges.
New developments for corrosion protection of concrete structures in Australia
