DIRAX for Corrosion Protection System for Directional Drilling and CrossingThis report states the requirements and test methods for heat shrinkable wrap around sleeve systems to be used in directional drilling applications for corrosion protection and sealing of joints in pipe structures with a maximum operating temperature of 60C or less.
The DIRAX system comprises two heat shrinkable wraparound sleeves closed with a patch closure and a two component solvent free epoxy primer. The main sleeve is fabricated from a minimal 1.4mm thick irradiation crosslinked thermally stabilized, fiberglass reinforced heat shrinkable woven polyolefin backing that is coated internally with a minimal 1.0mm thick high performance hotmelt adhesive. Adhesion to bare steel pipe surfaces is enhanced by the application of the primer.
The sleeve is closed using a special low profile closure patch. The closure provides sufficient strength to withstand the shrink forces during installation.
The main sleeve edge profile that enters the soil first is smoothed by the application of an additional narrow wrap around sleeve of the same construction as the main sleeve.
The systems are installed using propane gas torches. First the primer is mixed and applied. While still wet, the wraparound sleeves are shrunk down onto it. When heated above 125C, the sleeves shrink tightly around the substrate onto the wet primer. During recovery, the adhesive softens and flows to form an intimate bond with the primer and curing of the primer is initiated. The bond strength builds up during cooldown and is fully retained after completion of the job.
The heat shrinkable sheets are manufactured from a radiation crosslinked, thermally stabilized, UV resistant heat shrinkable fabric, composed of a fiberglass reinforcement and polyolefin fibers embedded in a polyolefin matrix.
The inner surface of the heat shrinkable sheets is coated with a controlled thickness of a hotmelt adhesive.