One (1) Percenters – Allowable Bare Areas (ABAs) Horizontal Directional Drill (HDD)

Abstract Since Horizontal Directional Drill (HDD) has gained popularity over the last few decades, there were no industry standards to the extent that has reduced the current requirements to prevent coating damage (less than 1 percent) and provide adequate external corrosion protection for the life of the HDD crossing. With all the benefits of HDD there are disadvantages: no possibility of pipeline maintenance due to excessive depths and difficulty controlling external corrosion. HDD installation increases the likelihood of coating damage during the pull back process of the carrier pipeline. This includes operational stress and damage from bed rock and other hard abradants especially when the current requirements are significantly higher compared to the line pipe installations. This also occurs in girth, longitudinal, and spiral welded pipe that is used and more importantly the type(s) of coatings used especially in those at joints and tie-ins. This paper will discuss HDD installations with inadequate coating design and installations with damaged coating that may result in future integrity related issues.