Valve Chlorine Service: Material Selection, Cleaning, and Design Per Chlorine Institute Standards

Chlorine is highly corrosive and toxic. Valves for chlorine service require special material selection and cleaning per Chlorine Institute (CI) standards. This guide covers CI Pamphlets 6, 7, and 69.

Dry chlorine: Iron and steel are passivated by dry chlorine. Carbon steel valves are acceptable for dry chlorine service below 120degC.

Wet chlorine (chlorine water): Highly corrosive. Attacks most metals except titanium and tantalum. Use titanium or Hastelloy C for wet chlorine service.

Body: ASTM A216 WCB (carbon steel) for dry chlorine below 120degC. For higher temperature or wet chlorine, use ASTM A351 CF3M (316L stainless steel).

Trim: 316 stainless steel or Monel (Alloy 400) for dry chlorine. For wet chlorine, use titanium or Hastelloy C-276 trim.

Seat: PTFE is acceptable for dry chlorine. For wet chlorine, use PTFE with titanium insert or all-titanium seat.

CI Pamphlet 6: Materials of construction for chlorine service. Defines acceptable materials for dry and wet chlorine.

CI Pamphlet 7: Cleaning of equipment for chlorine service. Requires degreasing and verification of cleanliness.

CI Pamphlet 69: Valves for chlorine service. Specifies design, material, and testing requirements.

All valves for chlorine service must be cleaned per CI Pamphlet 7. Remove all oil, grease, and particulate matter. Use halogenated solvents or alcohol for degreasing.

After cleaning, the valve must be dried and sealed with plastic caps. Do not use lubricants unless they are chlorine-compatible (per CI Pamphlet 6).

1. Bellows seal: Prevents packing leakage of toxic chlorine. Use PTFE or metal bellows depending on temperature.

2. Extended bonnet: For chlorine liquefaction service (below -34degC). Keeps packing above the frost line.

3. Fire-safe design: Chlorine is a strong oxidizer. Fire-safe valves are required for chlorine storage and transportation.

No. Wet chlorine rapidly corrodes carbon steel. Use titanium or Hastelloy C for wet chlorine service. CI Pamphlet 6 explicitly prohibits carbon steel for wet chlorine.

Dry chlorine has <150 ppm water. It passivates carbon steel. Wet chlorine has >150 ppm water and is highly corrosive. Always verify moisture content before selecting valve materials.

Ted Wang

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