Cable Protection Fasteners
Courtesy of West Special Fasteners
Filtration Screens from Wedge Wire
Courtesy of Hempel Wire
Superduplex is a generic term covering a range of highly alloyed grades developed for use in highly aggressive conditions, notably in sea water.
Approximate Composition – 25% Cr 7% Ni 3.5% Mo 0.25% N (nitrogen) plus optional Cu (copper) and W (tungsten). (Exact composition ranges vary between EN and ASTM standards).
This grade combines the following characteristics:
- Excellent pitting and crevice corrosion resistance (PREN > 40)
- Excellent stress corrosion cracking resistance
- Good yield strength (550 MPa minimum)
- Good impact toughness down to minus 50°C
- Cu bearing grades excellent resistance to sulphuric acid
- Knowledge required to maintain properties in fabrication
The superduplex grades are used in extremely aggressive conditions notably in seawater and high chloride or acidic chemical processes. Their complex metallurgy means that the process parameters must be kept within narrow ranges to maintain the required microstructure, corrosion resistance and impact toughness. This is especially true in welding. Therefore, fabricators require relevant training and approvals to work effectively with this material.
Oil and gas subsea, desalination, chemical processing, pulp and paper, valves, pumps, fish stunning electrodes, firewater systems.
Superduplex grades provide a combination of high corrosion resistance and strength in very aggressive conditions.