Why do Some Stainless Steel Pipes Need to Be Degreased?

  • By:Iris Liang
  • Date:2023/08/19

As we all know, stainless steel pipes need to be pickled and passivated before leaving the factory.

However, it is sometimes encountered that users require re-degreasing of pipes. As far as the pipeline is concerned, the more reasonable degreasing should be to complete the degreasing treatment of the entire pipeline system on site after the installation is completed. Generally, the manufacturer will not be allowed to degrease the pipeline, so what is the reason for requiring the manufacturer to degrease the pipeline?

What is degreasing stainless steel pipe?

With the increasing level of industrialization in our country and the vigorous development of petrochemical, natural gas, medical equipment, instrumentation, aviation, aerospace and other industry projects, the requirements for stainless steel pipe technology are also getting higher and higher. Such as the cleanliness of the pipeline, some users require that there should be no free rust, large particles of dust, welding slag, grease and other impurities inside.

Among them, the oxygen pipeline has quite strict cleanliness requirements. Most of the oxygen pipelines transport oxygen with a purity greater than 99.99%, with high pressure and fast flow. If the internal cleanliness of the pipeline cannot be guaranteed, trace amounts of oil and metal ions in the pipeline may be oxidized and collided with high-pressure pure oxygen, and the generated electric sparks will cause unimaginable serious consequences and even lead to disastrous accidents.

Among them, in the process of producing welded pipes, the process of internal leveling can be added to improve the smoothness of the inner wall of the welded pipe, reduce iron filings and material residues on the inner wall, and thereby reduce corrosion. Hangao Tech (SEKO Machinery) has more than 20 years of industry experience in stainless steel tube inner weld bead leveling equipment, and has accumulated a large amount of production data and customer cases, which is completely worthy of your trust.

Therefore, according to the process requirements, the new equipment pipeline needs to use chemical cleaning method to remove the oil and other impurities on the internal pipe wall before the device is started. At the same time, the supplier will also be required to degrease the pipeline.

What are the degreasing and cleaning steps for stainless steel oxygen pipelines?

Stainless steel oxygen pipeline degreasing cleaning steps: water washing → manual wiping degreasing → water washing → compressed air (or nitrogen) purging.

Water flushing: When flushing, use small-scale high-pressure water cleaning equipment to flush, and the pressure is controlled at about 0.6Mpa to ensure that the impurities inside the pipeline are flushed clean. The purpose is to remove ash, silt, detached metal oxides and other loose dirt in the pipeline.

Manual wiping and degreasing: Pour the cleaning and degreasing mixture into the cleaning basin, add it in proportion, mix it evenly before using it, and wipe it repeatedly. During the cleaning process, the cleanliness of the degreasing cleaning solution should be monitored. If the color of the degreasing cleaning solution becomes dirty, the existing degreasing solution should be drained and the degreasing cleaning solution should be reconfigured. The purpose is to remove all kinds of organic matter such as oil, graphite, anti-rust oil in the pipeline, so as to ensure that the interior of the pipeline is clean during installation and meet the requirements of equipment operation.

Water flushing: After the pipe is degreased, flush it with a large amount of water. When the flushing water flowing out of the pipe is clean, the water flushing can be ended. The purpose of water flushing after degreasing is to flush out the degreasing residue in the pipeline.

Compressed air (or nitrogen) purge: Use oil-free compressed air (or nitrogen) to purge, dry the inside of the pipe, and then wrap the pipe or parts with a clean plastic cloth to ensure the cleanliness of the inside of the pipe and avoid Secondary pollution.

Stainless steel pipe degreasing acceptance method

Pipeline degreasing treatment shall apply the degreasing solvent specified in the design and require degreasing. If it is not specified in the design, it can be degreased with carbon tetrachloride to check whether the degreasing is qualified.

Degreased stainless steel pipe packaging

After the pipeline is degreased and cleaned, the following requirements should be met:

1) Use ultraviolet light with a wavelength of 320-380nm to check the inner wall of the pipeline, and there should be no grease fluorescence.

2) Wipe the inner wall of the pipe with clean and dry white filter paper, there should be no trace of oil on the paper.

3) Or use a degreasing solvent to detect that the oil content does not exceed the requirements of the entrusting party.

4) Other relevant technical indicators proposed by the entrusting party.

The chemical cleaning and degreasing process of stainless steel oxygen pipelines standardizes the construction process of oxygen pipeline cleaning and degreasing, greatly improves the internal cleanliness of oxygen pipelines, and is a reliable guarantee for safe and efficient operation of oxygen pipelines. It is worthy of attention and promotion by stainless steel pipe manufacturers.




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