While 316Lis adequate for most applications, high chloride media, acidic pH levels, high temperature, time of contact, and equipment design can affect the corrosion of stainless steel.
The NEUMO Ehrenberg Group offers a wide range of special alloys: 316L; 1.4435; 904L; AL-6XN®; Ultra 6XN; Hastelloy® C22®/Alloy C22.
These alloys are commonly used in the biotech, pharmaceutical, personal care, home care, food, dairy, and beverage industries worldwide. The main concerns when choosing a special alloy are microbial contamination, system reengineering, maintenance downturns, production loss and safety of its employees and the environment.
The uniqueness (secret) behind the corrosion resistance of stainless steel is the formation of a durable and spontaneous ultra-thin film that covers the surface.
As long as the surface is clean and free of contamination, this film protects the steel in a process known as passivation.
The resistance of this film is dependent on the steel grade chosen and the conditions to which it is exposed. If the conditions become aggressive, the oxide film breaks down resulting in corrosion.
The main types of corrosion affecting hygienic and high purity application in aggressive chloride environments are pitting, crevice, and stress corrosion.
Optimum performance is obtained by the use of alloying elements, chromium, molybdenum, nickel, and nitrogen, all of which are very effective in improving corrosion resistance.
In today’s market there are a wide range of austenitic, superaustenitic, duplex, superduplex, and nickel-base alloys. Besides corrosion performance, other factors should be considered such as commercial availability, appearance, good mechanical properties, and fabrication characteristics.
The higher the PREN-value (Pitting Resistance Equivalent Number), the more resistant the alloy is to localized pitting corrosion by aqueous salt solution.
For stainless steel: PREN = %Cr + 3.3 x %Mo + 16 x %N
Some of the common applications for the special alloys; 904L/ 1.4539, 6XN/1.4529 and Hastelloy C22®/Alloy C22/2.4602 in the hygienic, biotech and pharmaceutical industries are as follows.
The superaustenitic also known as high-performance stainless steel share many characteristics with its standard grade counterpart like high tensile strength, good weldability, and formability becoming a better choice than duplex stainless steel. Additionally, it is a cost-effective alternative to more expensive nickel-base alloys.
HASTELLOY Alloy C-22®/ Alloy C22 is a nickel-chromium-molybdenum alloy with enhanced resistance to corrosion. The alloy provides exceptional resistance to pitting and crevice corrosion attacks in chloride-induced media as well as stress corrosion cracking.
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View / Download more information / technical specification about the MaxCore Special Alloy range.
Made in Germany, used Worldwide
Neumo UK Ltd is 100% owned by AWH (Armaturen Hötensleben) GmbH and stock and distribute AWH products here in the UK.