Steam Basics - What causes condensate to form?
When steam contacts a cooler surface it gives up or loses some of its heat. This
loss of heat results in the formation of little droplets of water called condensate. Even
though a steam system is well insulated, there is always some loss of heat
along the steam main or equipment, and condensate is formed. At the
lowest points in the system water is collected and drained away by a steam
trap to keep the heating or process steam as dry as possible.