Screen material selector for wedge wire

How the screen material selector works

The selector suggests a starting grade for a wedge wire screen from four inputs: the process medium, the chloride level, the temperature and the pH. Each result states the reason for the choice and shows the pitting resistance of the stainless grades.

• Chlorides drive pitting. Low chlorides and near-neutral water suit SS 304. As chlorides rise, the molybdenum in SS 316L adds resistance, followed by Duplex 2205 and Super Duplex 2507 for brackish water, seawater and high-chloride streams.
• Temperature increases the risk. Above about 60 degrees C, a chloride level that SS 316L tolerates at ambient temperature can call for duplex.
• Strong acids and hot chlorides (pH below 2, or hot seawater) need nickel alloys such as Hastelloy C-276, while Monel is used in seawater at velocity and in hydrofluoric service.
• Food contact normally means SS 316L, the usual hygienic grade.

The pitting resistance equivalent number is PREN = %Cr + 3.3 x %Mo + 16 x %N. Typical values are about 19 for SS 304, 24 for SS 316L, 35 for Duplex 2205 and 42 for Super Duplex 2507.

Worked examples

Swipe sideways to see the whole table.

Reading the result

The result is indicative. Crevices, velocity, oxygen content, cleaning chemicals and the cost of downtime also affect the choice, so SIMO engineering confirms the material for the operating conditions before the drawing is issued. The material selection guide explains each grade in more detail.