Pay attention to sealing and insulating pipes passing through walls and floors to prevent unnecessary pipe corrosion
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Problem: In production facilities, some pipes need to pass through the floor. To prevent sewage from flowing down through the openings, a water barrier should be placed around them, but this cannot completely stop sewage and debris from falling in. Some operators seal the annular gap between the pipeline and the water baffle with foam insulation material. During subsequent maintenance, it was found that the surface of the carbon steel pipes in the areas sealed with foam material had suffered severe corrosion, while the corrosion level in the rest of the pipes was normal. Discussion: Foam insulation materials create closed areas on the pipe surface, causing water vapor to accumulate and thereby intensifying the conditions for corrosion, which leads to accelerated corrosion of carbon steel pipes. In the case of stainless steel pipes, if the foam material contains chlorides, it may lead to chloride concentration, thereby causing stress corrosion cracking and damaging the pipe.
This issue occurs in pipeline floor slabs as well as where pipelines pass through platforms. In one of our company’s units, pipeline leaks occurred due to this problem. It’s somewhat easier to deal with situations where pipelines pass through platforms, as it’s possible to avoid using insulation joints at those points； Pipelines passing through the floor – this area is indeed a bit more challenging than the platform. Pipelines that pass through the floor come equipped with anti-corrosion measures. My suggestion is to avoid having joints in the areas where pipelines pass through the floor; instead, those joints should be placed further away from the floor surface. Additionally, the surface of the pipelines should be coated with asphalt for anti-corrosion protection. Please ask Teacher Wang for guidance.
In principle, heavy anti-corrosion measures are adopted for the outer walls of pipelines that pass through walls or floors. Elastic sealant can be used to seal holes.