Integrity of ductile iron pipe installed by horizontal drilling

摘要

The introduction of restrained joint ductile iron is rapidly gaining acceptance as an alternative pipe material for municipal engineering applications using horizontal directional drilling. The boltless restrained connection offers flexibility, ease of assembly, and positive restraint against endwise axial separation due to pulling during trenchless installations. This paper discusses the results of afield testing programme to evaluate the performance of restrained joint ductile iron pipe installed by horizontal directional drilling. The main area of concern is the potential corrosive effects on the pipe from the bentonite-based drilling fluid used in the installation. The research involved assessment of the installation durability and effectiveness of two combinations of externally applied, loose wrapped, polyethylene encasement to provide a protective barrier. Observations found that employing 002 mm linear low-density polyethylene encasement provided excellent protection to the ductile iron pipe against corrosion from drilling fluid and soils with low resistivities.