Carryover with steam, in steam technology, refers to transport of moisture and impurities with steam.

The moisture carryover with steam is quantified by the mass flow rate of liquid water per mass flow rate of steam. In boiler

Boiler

A boiler is a closed vessel in which water or other fluid is heated. The heated or vaporized fluid exits the boiler for use in various processes or heating applications.-Materials:...

s or steam generator

Steam generator

A steam generator is a device used to boil water to create steam. It may refer to:*Boiler , a closed vessel in which water is heated under pressure...

s producing saturated steam, it is typically about 0.1% but may increase with fouling

Fouling

Fouling refers to the accumulation of unwanted material on solid surfaces, most often in an aquatic environment. The fouling material can consist of either living organisms or a non-living substance...

and boiler impurities.

The carryover of impurities (for example, sodium, chloride, copper, silica) with steam can be divided into two parts:

1. mechanical carryover of the impurity with liquid water droplets entrained with the steam, and
2. vaporous carryover of the impurity in steam.

The total carryover is a sum of the mechanical and vaporous carryover. The vaporous carryover generally increases with increasing steam pressure. In low pressure boilers, the mechanical carryover of impurities prevails, possibly with the exception of more volatile impurities, like silica.

The impurity carryover can cause corrosion and fouling of steam turbines, reheaters, and superheaters.