MATERIALS
A supplier ’ s view
Rodney Rice , director of Langley Alloys , notes the continuing high demand for duplex and super duplex grades , particularly in the oil & gas sector . He highlights the strong demand not only in upstream applications but also in downstream uses , specifically mentioning valve components . Rice also points out the growing use of duplex in seawater-exposed applications , such as offshore wind power and in desalination plants , where water scarcity drives demand for duplex and super duplex piping . The versatility of duplex stainless steel extends beyond traditional applications .
Photo : Oliver Valves
When evaluating materials for valve applications , duplex stainless steels offer a balanced combination of properties , though they may not top every category individually . In terms of corrosion resistance and toughness , duplex grades perform exceptionally well , with heat resistance slightly lower but still impressive . However , it ’ s important to consider how these properties compare to other materials used in valve manufacturing . Corrosion resistance is a critical factor for many valve applications . While iridium , a dense and brittle transition metal from the platinum group , holds the title for most corrosion-resistant metal , it ’ s rarely used in valve construction due
to its cost and limited workability . More practically , certain grades of stainless steel , aluminium , copper alloys and nickel alloys are often chosen for their corrosion resistance in valve designs . Heat resistance is another crucial property for valves in high-temperature applications . Although materials like tantalum carbide and hafnium carbonitride ( HfCN ) boast extremely high melting points ( over 4,000 ° C ), they are not typically used in valve manufacturing . For comparison , titanium , which is sometimes used in valve components , melts at 1,668 ° C . Duplex grade 2205 , commonly used in valve applications , has a melting range of 1,385 – 1,445 ° C , while super-duplex grades melt at around 1,410 – 1,460 ° C , comparable to nickel at 1,455 ° C . Strength and toughness , essential for valve integrity under pressure , can be measured in various ways . While graphene holds the record for highest fracture strength ( over 125 GPa ), it ’ s not practical for valve construction . Among metals , tungsten is known for its impact resistance , with chromium , iron , titanium , vanadium and lutetium following closely . Duplex stainless steels , however , offer a practical balance of strength and toughness , making them suitable for a wide range of valve applications .
Advantages of duplex in valve applications
When considering materials for valve manufacturing , duplex stainless steel is a versatile choice that combines multiple desirable properties . This unique mix
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