[ Duplex ] are GD Engineering ’ s QOCs ( Quick Opening Closures ), used on FPSOs to quickly access pipelines and pressure vessels , which are made of super-duplex because of the favourable strength-toweight ratio , crucial on floating vessels ; and Oliver Twinsafe ’ s 12 " Class 1500 super-duplex valves , specified for the Shell Jackdaw platform in the North Sea , which are specially built to withstand the extreme conditions of the North Sea and therefore of outstanding size and complexity . A third example is the massive Gas Production Swivel Inner Part on Shell ’ s Prelude FLNG , forged in duplex and weighing 14,500 kg . Apart from offshore oil and gas , many other marine structures require duplex , including floating solar installations and offshore wind farms , to cope with salt corrosion , sand erosion and rough seas . Chemicals and petrochemicals are other dynamic industries in which duplex plays an important role . East Asia ( especially India and China ), the Middle East , and the USA are thriving markets . In East Asia , Stamicarbon is supplying its proprietary fertilizer technology to numerous projects , including a new high-pressure ( HP ) stripper for Mangalore Chemicals and Fertilizers in India , an upgrade of New Gold Chemical ’ s urea plant in Hulunbuir , and the new build of a similar plant in Zhangjiagang City . Super duplex is systematically applied in urea manufacture . In the 1990s Stamicarbon developed Safurex ® , developed in partnership with Sandvik ( now Alleima ), to provide resistance to active ammonium carbamate corrosion , chloride-induced stress corrosion cracking and other challenges unique
[ Duplex ] are GD Engineering ’ s QOCs ( Quick Opening Closures ), used on FPSOs to quickly access pipelines and pressure vessels , which are made of super-duplex because of the favourable strength-toweight ratio , crucial on floating vessels ; and Oliver Twinsafe ’ s 12 " Class 1500 super-duplex valves , specified for the Shell Jackdaw platform in the North Sea , which are specially built to withstand the extreme conditions of the North Sea and therefore of outstanding size and complexity . A third example is the massive Gas Production Swivel Inner Part on Shell ’ s Prelude FLNG , forged in duplex and weighing 14,500 kg . Apart from offshore oil and gas , many other marine structures require duplex , including floating solar installations and offshore wind farms , to cope with salt corrosion , sand erosion and rough seas . Chemicals and petrochemicals are other dynamic industries in which duplex plays an important role . East Asia ( especially India and China ), the Middle East , and the USA are thriving markets . In East Asia , Stamicarbon is supplying its proprietary fertilizer technology to numerous projects , including a new high-pressure ( HP ) stripper for Mangalore Chemicals and Fertilizers in India , an upgrade of New Gold Chemical ’ s urea plant in Hulunbuir , and the new build of a similar plant in Zhangjiagang City . Super duplex is systematically applied in urea manufacture . In the 1990s Stamicarbon developed Safurex ® , developed in partnership with Sandvik ( now Alleima ), to provide resistance to active ammonium carbamate corrosion , chloride-induced stress corrosion cracking and other challenges unique
Fourdrinier machine in a paper mill .
Largest floating solar park in Europe on a sand extraction lake , Bomhofsplas in Zwolle , The Netherlands .
to high-pressure urea synthesis equipment . This broadened into a family of proprietory super duplex grades known as E-type material for urea , ammonia and nitrates applications . These materials are used in strippers , condensors , HE tubes , plates , bars , flanges , fittings , piping , valves , couplings , welding consumables and more . They offer longer life , lower weight , increased HE surface area , lower maintenance and other advantages . The severely corrosive conditions of heat exchangers induced Alleima to develop SAF™ 3006 . This super-duplex grade , with 7 % nickel , 30 % chromium and 3.2 % molybdenum , is especially designed to handle acidic and caustic environments . It is an upgrade from grade 2705 , which has proved able to resist stress corrosion cracking in chloride conditions . The new grade is designed to provide better resistance to hydrochloric , sulphuric , formic or other acids and is intended , above all , for seamless heat exchanger tubes . Another appplication where duplex is important is the construction of doublehulled chemical tankers . Again . it is East Asia that is leading the way : in China , Xin Jiangzhou Shipbuilding Heavy Industry is making its debut as chemical tankers builder with orders for four vessels from Singapore-based MAC . Pulp & paper is another industry where corrosive chemicals are used . Growth of about 1.41 % per years is expected between 2025 and 2029 3 . Decline in demand for newsprint has been more than offset by demand for packaging ( much of which , ironically , derives for E-commerce ). A number of duplex grades are used at various stages of the manufacturing process . The most common is 2205 , used in the digester ( where the wood chips are “ cooked ” under high pressure ). The bleaching process ( which uses chlorine dioxide solutions , hydrogen peroxide or ozone ) and reactors can also use duplex , for example super-duplex 2507 in the piping . Super-duplex is also used in the suction rolls of the fourdriniers , machines through which the paper passes at around 100 km per hour while it is dewatered and rolled . Food & drink is another sector which has transitioned from using only austenitics
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