All pressure vessels, valves and piping of small air separation unit and large air separation plant as well as the vicinity of the piping (in contact with oxygen or cryogenic media) must be clean, dry and free from oil and grease before installation. air separation unit which has been degreased by the manufacturer and is not contaminated can be installed without degreasing; if it is contaminated with grease, it should be degreased.
materials such as aluminium and magnesium, requirements: pH ≤ 10 for aluminium and magnesium parts, cleaning temperature 70 a 80°C. After cleaning with alkali solution, the parts should be rinsed with clean water until there is no residual alkali, and then dried.
Before installation and useage, oxygen piping should be blown clean of residues in the piping with oil-free dry air or nitrogen until it is free of rust, dust and other dirt. Blowing speed should be greater than 20m/s. Where the surface of the parts in contact with oxygen and the surface of the parts in operation where the residual oil may be carried to oxygen, the residual oil of the grease shall not exceed 125mg/m2, it is strictly forbidden to blow the pipeline with oxygen.
