Duplex alloys were originally created to counter the corrosion problems caused by chloride-bearing cooling waters and other aggressive chemical process fluids. They are known to be Duplex because of its mixed microstructure with about equal proportions of ferrite and austenite, duplex stainless steels are a family of grades, which range in corrosion performance depending on their alloy content. The term “Super-Duplex” is used to denote highly alloyed, high-performance Duplex steel with a pitting resistance equivalent of >40 (based on Cr % + 3.3Mo % + 16N %).

With a high level of chromium, Super-Duplex steel provides outstanding resistance to acids, acid chlorides, caustic solutions and other environments in the chemical/petrochemical, pulp, and paper industries.

Duplex UNS S31803/ UNS S32205

Duplex UNS 31803 Flanges has outstanding corrosion resistance to seawater and most concentrations of sulphuric acid. In addition, it is also resistant to sulfide stress corrosion cracking (sour-gas environments). The high quality and performance of Duplex steel UNS 32205 Flanges are widely attributed to the high levels of chromium present as well as nitrogen and molybdenum. It has superior resistance to chloride pitting and crevice corrosion. It has outstanding corrosion resistance to seawater and most concentrations of sulphuric acid. In addition, it is also resistant to sulfide stress corrosion cracking (sour-gas environments).

Super Duplex UNS 32750 /UNS 32760

Super Duplex contains 25% chromium, 7% nickel, 3.6% molybdenum as well as copper, tungsten, and nitrogen, they are highly alloyed steel with high PREN for use in aggressive environments.

The alloy consists of around 40-50 percent ferrite in the annealed condition. The super duplex microstructure has the high strength of the ferritic grades in spite of retaining the corrosion resistance of the austenitic grades. It is common to see Super Duplex Steel being used as a practical solution to chloride-induced stress cracking. It also has outstanding resistance against sulfide-stress corrosion cracking in sour-gas environments.

Super Duplex UNS S32750 Flanges help the material withstand pitting and crevice corrosion. These flanges are also resistant to chloride stress corrosion cracking, to erosion-corrosion, to corrosion fatigue, to general corrosion in acids. They have good weldability and very high mechanical strength.

Super Duplex UNS S32760 Flanges are well known for their high impact strength and are used in industries including oil and gas applications, seawater, subsea pipework systems, heat exchangers and more.

Benefits of Super Duplex Flanges

High strength,

High resistance to pitting, crevice corrosion.

High resistance to stress corrosion cracking, corrosion fatigue, and erosion,

Excellent resistance to chloride stress- corrosion cracking

High thermal conductivity

Good sulfide stress corrosion resistance,

Low thermal expansion and higher heat conductivity than austenitic steels,

Good workability and weldability,

High energy absorption.

Applications of Super Duplex Flanges