Super Duplex Steel Fasteners are designed by incorporation of both nickel and chromium alloys that provide them with outstanding strength as well as resistance to high temperature. The most valuable aspect with super duplex stainless steel is that it unites the finest aspects of austenitic and ferritic stainless steel. The resulting special mix provides fasteners with high mechanical strength, economic efficiency, and excellent corrosion resistance at a comparatively simple manufacturing process. Moreover, these fasteners also provide excellent resistance to stress cracking and can be considered as a good option in the harsh industrial conditions. These are super duplex pipelines that are commonly utilized in offshore oil and gas as well as onshore pipelines where the environment in which the pipeline is in contact always poses a threat of extreme corrosion. This quality that they are not subjected to high-pressure situations without collapsing makes them also applicable in residential as well as commercial sectors.
Evolution of Super Duplex Steel Fasteners
Since the 1970s, super duplex steel fasteners have been among the favourable options in the industry mainly because of their outstanding performance and their versatility in a variety of service environments. Other versions like Super Duplex Steel 32750 Fasteners contain chromium and nickel alloys that provide a much higher tensile strength as compared to the conventional stainless steel. The necessity to overcome three nagging problems related to standard stainless steel fasteners, namely lack of corrosion resistance, lack of fatigue resistance, and low temperature strength, contributed a lot to developing super duplex steel fasteners. The initial issue was addressed by making the composition of the alloy have more chromium and nickel since these two elements are active in the inhibition of oxidation and rusting. The second problem was addressed by adding more nickel in the alloy design which enhanced toughness, flexibility and wear resistance at the same time. Lastly, molybdenum being an important alloying element was added so that super duplex steel fasteners could retain their structural shape and be deformed at high temperatures up to 1200 degrees Celsius. Super duplex alloys are always better than the traditional stainless steel alternatives in terms of corrosion resistance. They are very strong at high temperatures without loss in rigidity, which is the usual restraint of other alloy formulations at high temperatures.
Key Features of Super Duplex Stainless Steel Fasteners
- Super Duplex Steel has shown a high level of resistance to erosion in both the freshwater and saltwater environment and also its fined alloy composition has greatly increased the total corrosion resistance.
- Super duplex steel has one of the best yield strength, ductility and formability among the welding materials in the industry.
- Super duplex has one of the lowest corrosion rates of all high-strength steel materials, and it is one of the most corrosion-resistant options currently being offered in the market.
- This material has structural integrity and is not pitting at temperatures up to 425degC (825degF) of temperature.
Industrial Applications of Duplex Steel Fasteners
Duplex Steel Fasteners are used in the following industries
- Oil & Gas (Offshore and Onshore): Duplex stainless steel bolts and fasteners. These applications can not be matched by the corrosion resistance of saltwater and the mechanical strength. For more on the piping systems used alongside these fasteners, see our guide on Duplex Stainless Steel Pipes.
- Chemical and Petrochemical Processing:Reactors, heat exchangers, columns, and scrubbers all rely on duplex 2205 fasteners and super duplex bolts to maintain joint integrity in acidic and chloride-containing process media.
- Marine and Shipbuilding: Duplex fasteners are commonly used in the hull, ballast, and seawater cooling lines of the ship where the standard stainless would have been easily pitted and creviced.
- Desalination Plants: Super duplex fasteners are preferred material as used in membrane housings, pump casings and pressure vessels flanges in seawater desalination plants due to their high resistance to corrosion developed on them by chloride.
Source High-Quality Super Duplex Fasteners from Unifit Metalloys
At Unifit Fastener, we supply certified super duplex stainless steel fasteners and super duplex fasteners across grades 2205 and 2507, along with the full range of complementary piping products. Our inventory includes duplex pipes, fittings, flanges, and tubes regularly specified alongside fasteners in industrial projects.