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REHABILITATING THE INTERNALS OF PIPELINES AS LONG AS 20KM CAN NOW BE ACHIEVED
These new materials offer chemical, temperature and abrasion resistance for pipes transporting sour crude, acids, effluent, brine, hot gases and other chemicals. The coating system is also suitable for use on less aggressive lines where long life expectancies are required, including seawater, drinking water, cooling water, sewage and liquid wastes. Until recently, the in-situ coating process had only been used to apply thin film solvent-borne epoxy paints at circa 50-100 microns per coat. However, development work over the last three years has enabled Corrocoat to treat pipe internals that can be lined in-situ using vinyl ester glass flake coatings up to 1mm in thickness and the coating does not require post curing. Advantages include significant savings compared to the cost of a pipeline renewal, significantly reduced downtime, extension of the life of the pipeline beyond design expectations and little disturbance to the environment. The coating can be applied thickly to infill corrosion pits and repair channel erosion in the base of the pipe. The specially adapted glass flake filled coating materials can be made to cure in sub-zero temperatures as well as being useable in hot environmental conditions. Solvent-free formulation ensures no solvent entrapment to cause premature breakdown of the coating, whilst excellent resistance to runs and sags at joints reduces the possibility of defects. Moisture vapour transmission and permeation resistance is excellent resulting in very low rates of gas diffusion through the film attaining extended life expectancy. The Corrocoat pipe coating system involves a series of processes including mechanical scouring, using a scraper pig to remove loose debris and the products of corrosion, followed by mechanical cleaning using foam and wire brush pigs to ensure a clean, dry finish. The glass flake coating material is then applied using specially designed coating pigs. The coating is normally applied in two coats but can be applied in several runs along the length of the pipe to achieve a multi-layered, consistent coating thickness along the length of the pipe. Corrocoat’s in-situ internal rehabilitation system may currently be specified for pipes measuring 6" to 20" in diameter and up to up to 20km in length, including buried or submerged sections and either continuously welded or flanged designs. It is expected ultimately, that pipes up to 36" in diameter will be accommodated. The pipes must be piggable, so short radius bends or changes in internal diameters cannot be accommodated.
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