Thursday 25 April 2024

Alleima launches new super-duplex tube for acids

Sandviken, Sweden, March 4, 2024

Alleima, a global manufacturer of high value-added products in advanced stainless steels and special alloys, has introduced new advanced super-duplex tube tailored for acids.
SAF 3006 is a high-alloy duplex stainless steel tailored to enhance corrosion resistance in acidic and caustic environments. The new alloy, an upgrade to traditional super-duplex stainless steels, adds to the company’s growing duplex portfolio. The main application is heat exchangers in the chemical and petrochemicals industries.
“We’re thrilled to welcome this new super duplex to our expanding duplex family. It provides that ‘missing duplex tool’ for customers battling acids in heat exchangers, giving them that extra edge. With the addition of SAF 3006 (UNS S83071), we strengthen our presence in duplex materials tailored for acidic corrosion, where we see strong growth potential. Applications may include caustic evaporators, acid coolers and evaporators,” says Eduardo Perea, Market & Product Manager EMEA at Alleima Tube Division.
Pioneering the duplex revolution 
Alleima pioneered the ‘duplex revolution’ of the 1960s and 1970s, introducing a cost-efficient stainless-steel alternative to more expensive nickel alloy grades. The company continues to innovate in this area. Duplex grades, with a 50-50 austenitic-ferritic structure, offer more than twice the strength of standard stainless steels and superior corrosion resistance.
The groundbreaking SAF 2507 (UNS S32750), introduced by Alleima almost four decades ago in 1985, set the industry standard for combatting wet corrosion in a diverse range of industrial applications. Renowned for its exceptional performance in corrosive conditions, SAF 2507 offers excellent resistance to stress corrosion cracking (SCC) in chloride-bearing environments, as well as to pitting and crevice corrosion.
Tailored for acids
“SAF 3006 will complement SAF 2507 in dealing with corrosive conditions in heat exchanger tubing exposed to hydrochloric, sulphuric, formic or other acids. This is our super duplex tailored to resist acids,” says Perea. 
“From an R&D perspective, this new super duplex reflects a sharper focus on optimizing the material for acid corrosion resistance. Previously, most of our duplexes were developed with chloride resistance as the main focus, with high PRE levels to resist pitting and crevice corrosion. Resistance to acidic conditions was less prioritized. Now, we have fine-tuned the chemical composition to resist acidic environments better. This involves a high chromium content of 30 % and a molybdenum level of 3.2 % to maintain good structural stability and balancing of the alloying elements,” says Daniel Gullberg, Manager of Product Development CRA.
New innovation for acid environments
“SAF 3006 is an upgrade over existing duplex grades facing higher-than-desired corrosion rates and where extended equipment lifetime is wanted. You get all the benefits of traditional duplex steel in terms of strength, lighter weight and cost-efficiency, but tailored to resist acids. It can be used in acid production plants with or without seawater cooling,” says Oscar Öhlin, R&D Engineer at Alleima.
SAF 3006 will be produced in Alleima’s fully integrated value chain, from R&D to end product, with tight quality control and a strong focus on sustainable production. The tube is based on more than 80 % recycled steel and melted and produced using a high degree of fossil-free energy sources. Seamless tube and pipe in SAF 3006 will be supplied in standard heat exchanger dimensions. 
Advancing the chemical & petrochemical industry 
“The introduction of SAF 3006 marks the ongoing evolution of the duplex revolution Alleima started decades ago – now tailored for acidic conditions in heat exchangers. We look forward to collaborating with customers to advance their needs,” concludes Tom Eriksson, Executive Vice President and Head of R&D at Alleima. 


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