Pipe installed by the Horizontal Directional Drilling (HDD) method is typically unreachable for repair. Thus, the pipe coating needs to survive the initial installation to provide the longest potential for protection. There isn't currently a standard which guides coating selection industry wide, but this paper will provide guidance on potential ways to evaluate and can serve as a backbone for developing a standard.
This paper will identify the potential causes of pipe coating failure, from the design angles to the soil types, to the fracture methods of rocks, and pull forces. It will present a logical method for evaluating the condition of an HDD pull prior to its installation so that the right level of coating protection may be applied. The pipelines that carry our world's energy and industrial networks are a vital lifeblood of our society. HDD's play such an integral part in keeping all aspects of the pipeline and its construction running smoothly, the aim here it to ensure there are no hiccups along the way.
HDD pipeline installation is a valuable method, but there are limitations both in installations and in long-term maintenance. Often HDDs can be more expensive and complex because the pipelines have to go deeper than they would in shallow trenches which presents challenges with physical realities such as accessibility for troubleshooting if something goes wrong and almost no chance for repair or even visual inspection once the line is in place.
HDDs carry their own set of risks particularly when compared against other methods of pipeline installation. HDDs are nearly always installed in Hight Consequence Areas (HCA) and at the same time they are inserted into the ground by one of the harshest means possible. Hazards associated with horizontal directional drilling include environmental concerns from drilling mud releases, or dangerous outcomes from contacting other pipelines during the drilling process. HDDs are likely to encounter difficulty in providing uniform Cathodic Protection (CP) to the length of the pipe section due to variations in soil resistivity, drilling mud, and the presence of rock formations, nearby powerlines, or bodies of water. In addition to these hazards, the installation itself can result in significant damage to the anti-corrosion coatings which creates vulnerable points on the pipe where corrosion and pitting can begin. There is a lack of understanding and communication across the industry on how to handle these certain issues that arise during drilling and installation. For operators to avoid these risks it's important that they understand what the problems are so they can take action before it becomes an emergency situation in an HCA.
