Cleanrooms and equipment

In fabs, what is the main reason the inner surfaces of stainless steel pipes that supply high-purity gases are electropolished (EP)?

  1. ATo make the pipes lighter
  2. BTo smooth the inner surface and suppress particle generation and the adsorption and release of moisture and impurities
  3. CTo color the pipes so types can be told apart
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Answer: B. To smooth the inner surface and suppress particle generation and the adsorption and release of moisture and impurities

A rough inner surface sheds particles and adsorbs moisture and impurities that are later released little by little, lowering gas purity. Electropolishing makes the inner surface mirror-smooth and forms a stable passive film, so high-purity gas reaches the tools without being contaminated.

  • A. Weight reduction is not the purpose.
  • B. Correct. A smooth inner surface suppresses contamination.
  • C. Types are identified with markings and labels.
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