Steam check valves or steam non-return valves are installed in pipeline systems, to enable the movement of the medium in one direction only.

Steam check valves work entirely through the steam line fluid reaction, and thus no external actuation is needed. In this context, the flow direction expected or desired is called 'forward flow'.

Although steam check valves can effectively shut off the reverse flow, they should never be used in place of an isolation valve to contain live steam, in a section of pipe.

The 'reverse flow' is in the opposite direction. These forces may cause a wave of pressure to run up and down pipework until the dissipation of the energy

There are several reasons for the use of the steam check valves, including the Protection of any equipment item that may be affected by reverse flow, such as flowmeter, strainer, and control valves. For starters, water-hammer to test the pressure surges associated with hydraulic forces.

These hydraulic forces may cause a wave of pressure to run up and down pipework until the dissipation of the energy.