[ Duplex ] seawater , are environments where duplex grades are often applied . These have three types of environments : atmospheric , splash or submerged zones . Depending on the level of corrosivity , each can require duplex steels of varying strength . The most severe zone of all is the splash zone , where hazards include oxygen-rich seawater ( chloride environment ), wetdry cycles and UV radiation . In addition , other challenges include powerful wind or underwater currents , cold and sea spray and sand abrasion . For all these reasons , standard or super-duplex grades are required ; for the other two , lean grades can sometimes be enough . Recently , the Merkur offshore wind farm in the North Sea constructed the supports of the wind turbines using Outokumpa Forta 2205 duplex for its corrosion resistance , strength and flexibility . The turbine in question is the gigantic Heliade 150-6MW from GE , whose rotor has a diameter of 150 metres . Offshore wind farms also require valves made in duplex stainless steel . Oliver Twinsafe supplied Modular and Monoflange double block and bleed valves for the largest offshore wind project in the world , Hornsea 3 in the North Sea . The materials used included 316 , titanium and super-duplex . They were applied in cooling systems and firewater applications . Another growing marine application is boats . A few years ago , Sweden ’ s Stainless Steel Yachts ( SSY ) built a sailing yacht from super-duplex 2507 , combining excellent corrosion
[ Duplex ] seawater , are environments where duplex grades are often applied . These have three types of environments : atmospheric , splash or submerged zones . Depending on the level of corrosivity , each can require duplex steels of varying strength . The most severe zone of all is the splash zone , where hazards include oxygen-rich seawater ( chloride environment ), wetdry cycles and UV radiation . In addition , other challenges include powerful wind or underwater currents , cold and sea spray and sand abrasion . For all these reasons , standard or super-duplex grades are required ; for the other two , lean grades can sometimes be enough . Recently , the Merkur offshore wind farm in the North Sea constructed the supports of the wind turbines using Outokumpa Forta 2205 duplex for its corrosion resistance , strength and flexibility . The turbine in question is the gigantic Heliade 150-6MW from GE , whose rotor has a diameter of 150 metres . Offshore wind farms also require valves made in duplex stainless steel . Oliver Twinsafe supplied Modular and Monoflange double block and bleed valves for the largest offshore wind project in the world , Hornsea 3 in the North Sea . The materials used included 316 , titanium and super-duplex . They were applied in cooling systems and firewater applications . Another growing marine application is boats . A few years ago , Sweden ’ s Stainless Steel Yachts ( SSY ) built a sailing yacht from super-duplex 2507 , combining excellent corrosion
Inner Sheath
Dual layer armour package Cross section of a deep-sea umbilical .
resistance with a weight saving of up to 50 %, resulting in greater fuel economy . A polished hull reduced water friction and eliminated the need for anti-fouling paint . Since then , the same company has introduced a range of small boats , including , yachts and patrol boats , built from 2507 and hyper-duplex grade 3207 . In both cases , the material was supplied by Alleima ( then Sandvik ). According to SSY , these grades are superior to two materials that are sometimes used on light vessels : aluminium , which fatigues more quickly , is sensitive to fire and is susceptible to galvanic corrosion ; and carbon fibre , which cracks more easily , is nonrecyclable and sensitive to fire . Once again , only duplex has all the essentials covered .
Outer Sheath
Electric Cable ( power / signal )
3 Phase HV Cables
Fibre Optic Cable
25cr Super Duplex – Hydraulic Control , Injection of Service Chemicals & Hydrate Inhibitors
Wastewater and desalination Desalination is an obvious area in which duplex grades are applied , because of the exposure to saltwater . But wastewater treatment is increasingly turning to duplex because of the need to resist both corrosion and erosion . Type 2205 is used in evaporators , piping systems , heat exchangers , tanks , valves and reactors . Recently Invest-Tech designed a new type of wastewater treatment storage tank built of Forta LDX 2101 . This departs from the traditional round form because of the need to expand to accommodate increased capacity . Square or rectangular shapes are bolted together – though the process does require some welding . Therefore , apart from corrosion resistance , high pressure and weldability were important criteria .
Food storage A few years ago , water or food storage tanks would have been manufactured entirely of austenitic grades 304 or 316 ; later , manufacturers favoured a combination of austenitics on top and duplex for the lower part , which is under greatest pressure . Now it has
Diagrams showing how duplex is used on an offshore wind farm . Hull structure of SSY ’ s M17 Cruiser .
www . stainless-steel-world . net Stainless Steel World April 2024 17