Solutions for corrosion on the outer surface of pipelines
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This post was last edited by yqyabo on 2019-7-25 at 13:38. Corrosion of the outer surface of pipes inside the insulation layer: Solution: Apply a waterproof coating to the outer surface of the pipes to completely prevent water from coming into contact with the pipe wall.
This should be a cold-insulating pipe; for such pipes, the issue of condensation must be taken into account first – preventing water from condensing on the surface of the pipe – and only then can attention be paid to preventing corrosion of the pipe.
There is no need to replace the waterproofing after 30 years.
This waterproof coating bonds tightly to the pipe wall, preventing condensation from coming into contact with it.
Your pipeline’s insulation must not be properly sealed, and the quality of the primer applied is poor; when humid air comes into contact with the pipeline, it continues to condense, resulting in condensation water that corrodes the pipeline. Under normal circumstances, if the primer is applied properly and the insulation covering of the pipeline is sealed tightly, such problems are less likely to occur.
Such composite materials are generally porous due to the need for heat insulation, and it is difficult to prevent erosion by water and oxygen using this material alone; during operation, a small cut can be made in the insulating material from time to time to check the condition of the pipe walls.
It provides insulation against heat and cold; the outer layer can be made of photocurable sheets, offering high strength, seamless sealing for complete isolation, and corrosion resistance.
It is recommended that for such insulation pipes, an anti-corrosion coating be applied to the metal surface just before insulation. This anti-corrosion layer must be treated as a highly enhanced anti-corrosion system; it can be designed with 2 coats of primer and 2 coats of topcoat, resulting in a paint film thickness of over 200 microns. Such as 2 coats of epoxy zinc-rich (epoxy iron oxide) + 2 coats of epoxy topcoat. Then, a thermal insulation layer and a waterproof layer are applied, so that even if the waterproof layer is damaged, it will not cause corrosion to the metal. Additionally, for pipes with insulation layers that are prone to problems, proper inspection and management should be carried out.
Your suggestion is very suitable for new projects. This is an old project; if the entire system’s pipes are replaced, the costs associated with materials and construction would be high. Additionally, operations would have to be suspended for 2 months, which would have a significant impact on business operations. The advantage of using this waterproof coating is that, in addition to avoiding the need to replace pipes and thus not disrupting operations, the investment required is much lower than that for pipe replacement. Moreover, the 30-year warranty on this waterproof coating is one of the main reasons it gains customer approval.