Steam and condensate glossary

Make-up water

Make-up water – fresh water that is supplied to the boiler in order to replace water lost in the steam system.

Non-condensable gases

Noncondensable gases, non-condensables, incondensibles, incondensables, NCGs, etc. – gases that are called “non-condensables” because temperatures in the cryogenic range (around -150o C) are required to condense them. These gases are present in all steam systems. They increase corrosion and have a negative impact on heat transfer in exchangers, due to the fact that they behave as thermal insulation.


Pitting – corrosion of metal that takes the shape of very small corroded holes.

Plume of steam

Plume of steam – observable form taken by steam that escapes from a pipe, a piece of equipment, etc.

Pressure gauge

Pressure gauge – instrument for measuring fluid pressure (steam, air, etc.)

Pump trap

Pump trap – pump that propels the liquid coming from the condensation of steam (condensate).