Degreasing (de-oiling) of pipelines, valves, etc. is performed on special occasions, such as media that require oil bans, as well as oxygen pipelines and liquid oxygen pipelines that all require degreasing. The general air separation and gas industry pipelines and valves are mostly Degreasing is required. The general degreasing agents include acetone, trichloroethylene, tetrachloroethylene, and carbon tetrachloride, but the toxicity of acetone, tetrachloroethylene, and carbon tetrachloride are relatively large. Now they are generally banned. The more commonly used is trichlorin. Ethylene, degreasing effect fully meets the requirements. Degreasing has infiltrating method, wiping method, circulation washing method. Degreasing is qualified with a grease detector.