Around the world, including in the East Asia and Pacific area, steel manufacturers face significant pressure to reduce emissions from original equipment manufacturers (OEMs), regulators, and consumers. The rise in life cycle assessment is a testament to this increased focus.
For hard-to-abate industries like steel, reducing emissions and increasing the sustainability of material manufacturing processes is critical.
The challenge of developing sustainable innovations in materials and corrosion engineering was the key theme of the recent AMPP Malaysia East Asia & Pacific Area conference. The event enabled Alleima to discuss the benefits of its breakthrough super-austenitic stainless steel alloy, Sanicro® 35, which bridges anti-corrosion, performance, cost efficiency, and sustainability.
At Alleima, sustainability is a way of life. It is firmly established in our operations and is integrated into our strategy. Our sustainability targets have been reviewed and validated by the Science Based Targets initiative (SBTi) and are aligned with the latest climate research. Alleima was recently once again awarded a gold medal by EcoVadis, a leading supplier of sustainability assessments. Our stainless steel production has been based on recycled steel for over 100 years, and melting is done in a furnace powered by 100% fossil-free electricity.
Sanicro® 35 is a relatively new material that bridges the performance/corrosion and cost efficiency gap between stainless steels and more expensive high-nickel alloys. And it bridges the sustainability gap toward more sustainable steel manufacture.
Where performance meets sustainability
Due to its superior properties, Sanicro® 35 displays versatility across different industries and applications, including heat exchangers (HX) and hydraulic and instrumentation (H&I) systems.
For heat exchangers, these include refineries (overhead condensers, REAC, and gas cleaning/sour water), petrochemical and chemical (chlorinated hydrocarbon, PTA, organic and inorganic acids), seawater coolers, and biofuel and other renewable energy applications.
For H&I systems, Sanicro® 35 is ideal for use in environments requiring specific grades. These include process plants in coastal areas high in chloride, offshore oil and gas, marine, elevated temperatures, and other highly corrosive conditions
The environmental benefits of Sanicro® 35 stem from its lower carbon footprint, achieved through a reduced nickel content, resulting in lower cradle-to-gate emissions compared to high-nickel materials like alloy 625. Based on verified cradle-to-gate LCAs from Alleima, replacing 243 heat exchangers in European refineries at end-of-life with Sanicro® 35 instead of alloy 625 could reduce CO₂ emissions by approximately 3,700 tonnes.
The balanced chemistry of Sanicro® 35 gives high structural stability. It is not as sensitive as duplex to forming intermetallic phases, especially during welding. Its mechanical properties, including a high yield strength and good ductility, create significant weight reduction possibilities compared to grades such as 304L, 316L, 254SMO, and alloy 825.
Corrosion properties
In general corrosion tests with organic acid, Sanicro® 35 showed the best resistance in formic acid compared to alloy 2507 (S32750), alloy 654 (S32654), alloy 904L (NO8904), and 254SMO (S31254). In sodium hydroxide tests, it demonstrated resistance up to the highest tested temperature (145ºC) and clear advantages over S32654, S31254, and S32750.
Sanicro® 35 has good resistance to hydrochloric acid and high resistance to sulfuric acid and nitric acid, compared to some of the common stainless steels and duplexes used in each acid environment. Sanicro® 35has excellent resistance to pitting corrosion. Its PREN value of ~52 is comparable to alloy 625. This is significantly higher than the PREN values for super duplex and 6 Mo austenitic grades, which are commonly used in seawater applications. For reference, SAF 2507 and Alleima 254 SMO have a minimum PREN value of 42.5. Sanicro® 35 has excellent crevice corrosion resistance in chloride environments and excellent resistance to stress corrosion cracking.
Extending tube life at an Indian fertilizer plant
A fertilizer plant in India was experiencing severe corrosion in pneumatic instrumentation line tubes made from 316L stainless steel. The tubes need to be replaced every month.
In 2022, the tubes were replaced using Sanicro® 35and have been running successfully without any failures since installation.
Reducing costs at a renewable fuel pre-treatment plant
A renewable fuel pre-treatment plant in Europe required replacement heat exchanger tubing. The initial material selection was alloy C-276. However, as this grade is very expensive, the project EPC and end-user contacted Alleima to discuss possible alternatives.
Through advanced laboratory testing, it was proven that Sanicro® 35 would be corrosion-resistant in the process environment. The tube sheet solution was carbon steel, explosion clad withSanicro® 35. For the project, the cost savings on the tubes alone were over 1.2 million Euros.
Standards and approvals
Sanicro® 35 HX and H&I tubing meet product standard ASTM B163. Pipe follows ASTM B677. Bar and wire meet ASTM B149, while plate, sheet, and coil adhere to ASTM B625.
The material complies with NACE MR0175/ISO 15156-3:2015 (Petroleum, Petrochemical, and Natural Gas Industries - Materials for Use in H2S-Containing Environments in Oil and Gas Production - Part 3: Cracking-Resistant CRAs (Corrosion-Resistant Alloys) and Other Alloys) for type 4a and type 4c materials. It also complies with ANSI/NACE MR0103/ISO 17495-1:2016 (Petroleum, petrochemical and natural gas industries-Metallic materials resistant to sulfide stress cracking in corrosive petroleum refining environments) for highly alloyed austenitic stainless steels and nickel alloys.
Approvals include ASME Code Case 2982-2. Boiler and Pressure Vessel Code, Section VIII, Division I and II for the USA, and Pre-approval for Particular Material Appraisal (PMA), TÜV file 1326W043219 Rev. 4.0 in Europe.
One solution, many applications
Sanicro® 35 is a versatile, super-austenitic alloy that bridges the corrosion, cost efficiency, and sustainability gap between stainless steels and nickel alloys. It offers a broader temperature range than duplexes, excellent mechanical properties, extremely high localized corrosion resistance, very good general corrosion properties, and good structural stability, formability, and weldability.
Despite being a relatively recent addition to the Sanicro® family, Sanicro® 35 is already delivering proven performance in various applications and service conditions across APAC, the USA, and Europe.
In the acceleration toward greater sustainability in steelmaking, Sanicro® 35 is acost-efficient alternative to more expensive high-nickel alloys and is a material solution for upgrading equipment suffering from corrosion.
It’s a material that helps users reduce corrosion risk, extend equipment life, and at the same time stay cost-efficient - all while supporting more sustainable choices in material selection and long-term operation.
If you’re looking for a reliable, high-performing material, Sanicro® 35 is certainly worth considering.