Flash Steam

Definition - What does Flash Steam mean?

Flash steam is the steam that is generated from a hot condensate when the pressure within a pipe decreases. Flash steam is the same as normal steam, except that flash steam is produced when the stream is exiting a boiler or steam generator and there is a pressure drop at the boiler's outlet (i.e., the exit of the steam trap).

Inside a boiler or a steam generator, heat is provided to the condensate, which causes the temperature and pressure to increase and convert the condensate into vapors.

Corrosionpedia explains Flash Steam

Flash steam occurs when the saturation point of water varies according to the pressure inside of a pipe or container.

The flash steam ratio is given by the formula:

Flash Steam = (Hf1 – Hf2) / Hfg2

Where, Hf1 represents specific heat of saturated water at the inlet of the boiler

Hf2 represents the specific heat of saturated water at the outlet of the boiler

Hfg2 represents saturated steam’s latent heat at the outlet of the boiler

Due to flash steam, steel and copper pipes are vulnerable to internal corrosion where they are connected at the outlet (i.e., at the steam traps). If the steam trap becomes clogged it will exert high stresses at that portion of an internal piping system, which can remove any internal corrosion resistance coating and lead to thinning of the internal metal surface. The steam can carry these impurities and cause damage further down the pipeline.
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