Chlorine is a dangerous and toxic material. It’s a greenish-yellow, noncombustible gas with a distinctive, pungent odor. The gas acts as a severe infliction if inhaled. It is noncombustible in both gaseous and liquid states. However, it’s capable of supporting the combustion of certain substances.
Application of Chlorine in various industries:
Chlorine is especially used in producing chemicals. These embody solvents, pesticides and herbicides, plastics and fibers, refrigerants and propellants. It’s also an ingredient in bleach, deodorizer and disinfectant. Additionally, chlorine is widely employed in bleaching pulp, paper, and textiles for drinking water and swimming pool purification; in sanitation of industrial and sewerage wastes.
Chlorine service will be divided into two categories: wet systems (greater than 150 ppm of water) and dry systems (less than 150 ppm of water). Knowing whether or not the chlorine system is wet or dry determines what materials of construction will be selected to best perform within the system.
The risk associated with Chlorine
Chlorine service is typically difficult. It’s extremely reactive as a liquid or gas and may simply go from a generator to a personal or environmental catastrophe if extreme precautions aren’t taken. chlorine applications aren’t for the inexperienced or unverified.
Valves for Chlorine Service
Some valve varieties are better than others when it comes to chlorine processes and operations.
Several factors make the globe valves one of the most effective selections for chlorine use.
- Ability to produce a tight shutoff.
- Ability to verify whether it’s open or closed.
- The multi-turn operation that provides for slow and careful opening and closing.
- Bi-directional seating – its ability to shut off in each direction while not trapping liquid within.
- Any leak can permit moisture from the air to enter the system inflicting corrosion thus versatile graphite or PTFE ought to be used for packing.
Providing tight shutoff, the ball valve contains a reliable stem seal design. They could be full-bore or reduced-bore. A full-bore (or full-port) valve has an opening the same diameter as the piping, therefore there’s no restriction in flow through the valve, as a result of chlorine that gets trapped within the valve may expand, ball valves ought to have a release for any ensuing pressure. Either a relief hole bored into the ball or pressure self-relieving seats can be used.
Single-seated segmental ball valves, on the other hand, don’t trap liquid once they are closed. They’re usually used as control valves.
Fully-lined ball valves are lined with a fluoropolymer resin, thus there’s no metal to chlorine contact. they could be used with wet or dry chlorine gas without worrying about corrosion.
Both soft-seated superior butterfly valves and fully-lined butterfly valves are used.
The soft-seated valves are helpful in large pipes.
In fully-lined butterfly valves, like fully-lined ball valves, the fluoropolymer lining prevents the chlorine from touching any metal.
Criteria for valves selection
In order to prevent leakage through the stem seal in the presence of huge or frequent temperature fluctuations, consider using bellows seals or live-loaded packing.
Consider both ambient and processing temperatures when choosing valve materials. keep in mind that throttling applications will produce pressure differentials, leading to lower temperatures.
Wet or dry chlorine
Wet chlorine is extremely corrosive to a variety of metals, whereas dry chlorine isn’t. If the chlorine being processed is dry, however, might become wet, choose materials that are appropriate for both.
Flashing and cavitation
The capacity for flashing and cavitation should be kept in mind and its avoidance should be considered when sizing the valve.