MATERIALS of characteristics makes duplex grades competitive against other stainless steel grades , carbon steel and alternative materials across various industries . The advantages of duplex stainless steel in valve applications include : 1 . Corrosion and erosion resistance : Essential for valves in aggressive environments , such as seawater or chemical processing .
2 . Heat resistance : Allows for use in high-temperature applications , though not as extreme as some specialised alloys .
3 . Strength : Provides excellent mechanical properties , crucial for maintaining valve integrity under pressure .
4 . Cost-effectiveness : Offers a balance of performance and affordability , particularly when considering lifecycle costs .
5 . Formability : Allows for easier manufacturing of complex valve components .
6 . Recyclability : Contributes to sustainability efforts in valve production and end-of-life management .
These combined properties make duplex stainless steel an attractive option for valve manufacturers seeking to improve performance , durability and costeffectiveness .
Duplex stainless steel valves across industries
Duplex stainless steel valves have found widespread application across multiple industries due to their unique combination of properties . Let ’ s examine how these duplex stainless steel valves are utilised in different sectors :
• Deepwater oil & gas Longitudinally-welded or seamless umbilicals , which bundle together the various lines ( flowlines , power , data , water , chemicals , fluids , etc .) between subsea wells and the platform , often need to span long distances in deep water , so a material that can both resist corrosion and withstand high pressures is called for , such as superduplex type 2507 . Flexible pipes or risers , used to convey oil or gas from seabed to surface , also require high grades . Depending on the depth , super-austenitics , duplex in lean ( 2101 ), standard ( 2205 ) or superaustenitic ( 2507 ) grades are applied . Duplex is also finding use in valves that handle monoethylene glycol ( MEG ). This chemical is used to inhibit hydrate formation in pipelines , which can cause blockages . Recently Oliver Twinsafe supplied double block and bleed valves for the MEG injection pump systems of an offshore project , made of A182 F55 super-duplex stainless steel .
• Marine installations Oil & gas or wind platforms or solar power systems , being exposed to 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 .
• 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 .
Conclusion
Looking ahead , the role of duplex stainless steel in valve applications is set to expand further . As industries push the boundaries of operational environments and seek to optimise their processes , the demand for materials that can withstand extreme conditions while offering long-term reliability will only increase . Valve manufacturers are already exploring new duplex alloy compositions and innovative manufacturing techniques to enhance performance even further . Additionally , the growing focus on sustainability in industrial operations may increase the appeal of duplex stainless steel valves , given their durability and potential for reducing replacement frequency . www . valve-world . net Valve World September 2024
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