Sanicro® 35 is an excellent corrosion resistant alloy for harsh environments

This high performance corrosion resistant alloy, with properties like a nickel based alloy but with a price profile of a stainless steel, was first launched by Alleima as seamless tubes and later by Outokumpu as sheet and plate.

Sanicro® 35 provides excellent corrosion resistance to give equipment a long service life in demanding environments. It can withstand a wide range of corrosive conditions, including seawater, acid and alkali, erosion-corrosion, pitting and crevice corrosion as well as stress corrosion cracking (SCC). In addition, it has high mechanical strength together with excellent fabricability, e.g., formability, weldability and machinability.

These properties make Sanicro® 35 ideal for equipment such as reactors, heat exchangers and processing vessels in direct contact with high temperature seawater applications, sour environments and other corrosive chemicals.

Sanicro® 35 has now been available on the market for a couple of years and a number of successful references have been reported.

• Ventilation duct in a pulp mill: Earlier the stainless steel UNS N08904, also known as Alloy 904L, was used in the environment consisting of a wet sulfuric acid stream of 50-100°C. The 904L alloy lasted only three weeks before it needed to be replaced resulting in significant replacement costs.  Sanicro® 35 was selected as showing promising corrosion and erosion properties, and with a PRE value close to that of Alloy 625.  The new impellers, fabricated from 5.5mm thick cold rolled Sanicro® 35 sheets, have been used for more than a year without any reported failures. 
• Seawater cooled heat exchanger for Ethylene production. Sanicro® 35 was selected for the seamless heat exchanger tubes as well as for the tube plates. Material selection was based on the resistance to localized corrosion that in other cases might be caused by the chloride content of the Mediterranean water in combination with the temperature. The temperature of the seawater is 20 → 40°C and of the ethylene 128 → 40°C. Outokumpu supplied round discs with a thickness of 30mm.
• A biofuel refinery has selected Sanicro® 35 for several different applications. The material selection was made after extensive testing and environment of renewable fuels is challenging. Sanicro® 35 is used for heat exchanger tubes, channels, partition plate and baffles for in total seven tube and shell heat exchangers in the pre-treatment of the renewable oil feedstock. Further 10mm thick hot rolled plates of Sanicro® 35 were used to produce a 150 meter long tube reactor loop for cleaning the incoming feed to the hydrothermal cleanup pretreat process.   

“Sanicro® 35 is a material of the future. We expect it to play a big role in the market to cost efficiently combat corrosion”

says Marie Louise Falkland, Outokumpu’s Senior Technical Manager.

“Its good balance of alloying elements, its property profile of corrosion resistance, mechanical strength and excellent fabricability makes it perfect to be the new “work horse material” for many applications in the harshest environments, replacing nickel base alloys at a competitive and stable price.”

In cases where the well-known stainless grades have been regarded as not sufficient the traditional choice has been to go to high nickel and costly nickel based alloys. With Sanicro® 35 now being available a smarter, more cost efficient and proven alternative is possible. Traditionally, engineers have used nickel-based Alloy 625 or C-276 as the go-to grades for equipment in corrosive environments. However, the cost of these alloys is high and variable due to its alloying content, which includes approximately 60 percent nickel and up to 10 and 15 percent molybdenum respectively. Both these alloying elements are regularly experiencing price volatility, making the cost of them unpredictable. In turn, this creates challenges in project planning and delivery.

Sanicro® 35 provides similar performance while reducing exposure to this market volatility as it contains only 35 respectively 6.4 percent of nickel and molybdenum.

Outokumpu is producing Sanicro® 35 as part of its Ultra range under license from Alleima, the expert in advanced alloys that was formerly known as Sandvik Materials Technology. Alleima introduced the grade in 2020 and has since delivered seamless tube to the market, e.g. as heat exchanger tubes in traditional and biofuel refineries, in wastewater treatment, and in chemical process industries such as phosphoric acid acetic acid and in fertilizer plants. 

Outokumpu is offering Sanicro® 35 as hot rolled plate 8 up to 50 mm thick and cold rolled sheet 0.4 – 5.5 mm thick This is complemented by Alleima’s production of seamless tube and bar to provide the market with a range of product forms.

Sanicro® 35 in the form of sheet and plate is covered by ASTM B625, seamless tube and pipe is covered by ASTM B163 and B677 and bar is covered by ASTM B649 and all these products forms by ASME Code Case 2982-2, Boiler and Pressure Vessel Code, Section VIII, Division I and II. For the European market the Vd TÜV Pre PMA 1326W232560 is used for flat products and for the tubular Vd TÜV Pre PMA1326W043219 can be used. This creates the opportunity to adopt the grade in pressure vessels.

Sanicro is a trademark owned by Alleima AB.