Note: If PTFE-lined pipe is used, the temperature limit is 300°F
(150°C). At temperatures above this, a reaction may result between
the carbon steel outer shell and chlorine permeating through the PTFE,
possibly causing a fire.
The physical properties of chlorine do not allow it to exist free in
nature. It is found only in combination with other chemicals, primarily
sodium chloride, from which it is electrolytically extracted from
commercial use.
Liquid chlorine is a clear amber fluid with a density approximately
1.5 times that of water. Under atmospheric temperature and pressure
it evaporates readily, one pound forming about five cubic feet of a
highly irritating greenish gas. Neither gaseous nor liquid chlorine
is in itself combustible, explosive or electrically conductive.
Chlorine gas will support combustion, and certain chlorine compounds
are explosive.
Near the liquefaction temperature, gaseous chlorine does not follow
Boyles' Law. Under conditions of rising temperature or decreasing
pressure its behavior more nearly approximates that of an ideal gas.
Above 200°C (392°F) it follows Boyles' Law almost exactly.
At ordinary temperatures, dry chlorine does not corrode steel or
other common construction materials, although it will react with
mercury and tin and will ignite titanium spontaneously. At elevated
temperatures or in the presence of a few ppm of water, however,
chlorine becomes highly corrosive to practically all metals and
alloys.
The section of a piping material for chlorine is critically dependent on
control of the temperature-pressure relationship of the chemical in the
process stream.
