DUPLEX & SUPER DUPLEX
Special Piping Materials is renowned for the high volume of Duplex and Super Duplex
products that it stocks. It supplies these materials to countless companies around the
world who use its product’s in numerous applications in many different situations.
Special Piping Materials can supply many different products in both Super Duplex and
Duplex such as welded pipes, butt weld fitting, flanges, forged fittings, seamless pipes
and many more. They are available to buy from any of the company’s offices across the
Duplex stainless steels have a mixed microstructure of austenite and ferrite, the aim
being to produce a 50/50 mix, although in commercial alloys, the mix may be 40/60
Duplex steels have improved strength over austenitic stainless steels and also improved
resistance to localised corrosion, particularly pitting, crevice corrosion and stress
corrosion cracking. They are characterised by high chromium (19–28%) and
molybdenum (up to 5%) and lower nickel contents than austenitic stainless steels. The
most used duplex stainless steel are the 2205 (22% Chromium, 5% Nickel) and the 2507
(25% Chromium, 7% Nickel); the 2507 is known as “super duplex” due to its higher
resistance to corrosion.
The mechanical properties of Duplex steels are approximately double those of singular
austenitic steels, and resistance to stress corrosion cracking is far superior to type 316
stainless steel in chloride solutions. Duplex material has ductile or brittle transition at
approximately -50 degrees.
Super Duplex pipe is known to have better stress corrosion, cracking resistance and
mechanical properties than any other type of steel. Super Duplex is an austenitic
ferritic iron chromium – nickel alloy with molybdenum addition. It has good resistance
to pitting and a very good tensile strength and high resistance to stress corrosion
cracking at moderate temperatures, compared to that of conventional austenitic
The high corrosion resistance of Super Duplex pipeline supplies makes them ideal for
onshore and offshore environments in oil and gas applications. Please see our industry
pages for more information regarding the implications of Super Duplex piping.
All Duplex and Super Duplex materials stocked by Special Piping Materials are tested in
accordance with international standard such as Norsok M630、Shell MESC.