Q.What is Erosion-Corrosion in Steam Service?

Depending on the steam quality, Let-down valves are subject to erosion-corrosion when pressure drop exceeds 1000kPa. Hard facing is mandatory to prevent erosion-corrosion. It is also recommended to use 2¼Cr-1Mo spool downstream of let-down valve (4 diameters downstream).

Erosion-corrosion is a major concern in wet steam.

The pH of the water is also an important factor for the susceptibility of CS material to erosion-corrosion. Increasing the pH to 9 can decrease the erosion-corrosion significantly. Controlling the pH of BFW is of prime importance and shall be investigated during corrosion study and material selection.