Process materials (gases and chemicals)

Why is moisture in halogen-based gases such as hydrogen chloride controlled especially strictly in gas piping?

  1. AMoisture makes the gas lighter
  2. BWith moisture, it forms a corrosive acid like hydrochloric acid that corrodes stainless piping and causes metal contamination
  3. CMoisture changes the gas's color
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Answer: B. With moisture, it forms a corrosive acid like hydrochloric acid that corrodes stainless piping and causes metal contamination

Dry hydrogen chloride barely corrodes stainless steel, but with added moisture it becomes highly corrosive. If the pipe interior corrodes, metals such as iron and chromium enter the gas and contaminate wafers, and particles are generated. Moisture is therefore kept extremely low.

  • A. A change in weight is not the problem.
  • B. Correct. Moisture makes it corrosive and causes metal contamination.
  • C. A color change is not the problem.
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