Columbus Stainless

Choosing the right metal for the future.

advantage is that stainless steel is also considered an environmentally-sustainable material of choice, since it is 100% recyclable and is produced using predominantly recycled materials. The future of manufacturing is indeed Stainless.

Columbus Stainless, based in Middleburg, Mpumalanga, is a subsidiary of the Spanish group of companies, Acerinox SA, and Africa’s only producer of stainlesssteel flat products (coils, plates and sheets), with global distribution networks to final customers, stockists, engineering shops and mines.

The company supports the livelihoods of 1 250 employees and 600 contractors and we create in the region of 150 job opportunities annually for young trainees. Through its BBBEE programme, Columbus Stainless actively promotes doing business with small, medium and micro enterprises (SMMEs) owned or controlled by black entrepreneurs that are able to supply quality products and services in a timely and competitive fashion.

We are proud to have contributed to the supply and development of stainless steel for close to six decades and will continue to support the growth in Africa’s manufacturing industry through sound technical advice and premium customer service.

For most projects, current economic constraints require a balance between materials of construction selected and ultimate cost savings. The selection of stainless steel in this economy becomes the obvious choice. Stainless steel is a versatile metal of construction – its corrosion resistance and elegant appearance offers longevity and low maintenance in service. The added

Columbus Stainless produces the three main families of stainless steel, namely Austenitic, Ferritic and Duplex grades, which are suitable for most applications including agro-processing, food-processing equipment, mining and power generation – including nuclear, chemical, automotive and manufacturing industries.

Ferritic Stainless Steel: Commonly known as plain chromium steels. Typical examples include grades 430, used for applications like cutlery, cookware and architectural applications like wall cladding, hand rails and balustrades.

Utility Ferritic Stainless Steel: 3CR12® is a world-renowned low-cost utility ferritic stainless steel developed by Columbus Stainless and is used in structural applications. This material bridges the gap between coated carbon steels and the traditional higher alloyed stainless-steel grades. Due to excellent properties in wetabrasion conditions, 3CR12® is used successfully in the mining industry to fabricate ore-handling equipment, conveyor-belt systems and ore wagons. Applications in the agro-processing industries include handling and processing equipment, handrails, floor gratings and walkways. 3CR12® has seen great success and longevity in roofing and cladding applications, even in highly corrosive ammonia-containing environments like chicken farms, piggeries and other livestock holding facilities.

Austenitic Stainless Steel: These steels are alloyed with chromium and nickel for improved corrosion resistance, fabricability and exhibit good strength properties both in cryogenic temperatures (for example, cold storage containers) and high temperatures (ovens, stoves and cookware). Common grades include 304 and 316, which are used extensively in the food- processing industry, demanding high hygienic properties. Typically used in agriculture and abattoirs (including dairy processing and meathandling equipment, food and beverage storage tanks); catering and hospitality (cooking utensils, food-processing equipment, cold storage and healthcare industries for medical equipment and surgical tools); mining and chemical industry (cathode plates, processing tanks).

Duplex Stainless Steel: These grades exhibit high strength, good resistance to stress corrosion cracking and superior corrosion resistance. Popular grades include lean duplex 2304 and standard duplex grade 2205. Successful applications are in the paper and pulp industries, chemical, petrochemical and mining industries for various processing equipment and storage tanks. Due to their superior corrosion resistance these steels can withstand harsh marine environments. Our duplex stainless steel grade 2205 has been used and qualified in South African nuclear applications.

Case study: 3CR12 railway electrification masts in Gqeberha

Corrosion is the natural, gradual deterioration of metals reacting with their environment, compromising the useful properties of metals and structures, including their strength and structural integrity. In the ambient environment, metal alloys tend to revert back to their natural stable states. Carbon steels, for example, are made up of iron and a combination of other alloying elements. Without any additional surface protection, they tend to form a layer of rust (iron-oxide) which is brittle and exfoliates, exposing a new fresh layer of steel to be attacked. This cycle continues with devastating effects to equipment and structures due to resultant loss in through-thickness and inevitably causing perforation. Stainless steels have a unique advantage in that a thin, self-repairing protective layer forms on the surface of the steel. This chromium oxide passive layer gives the steel its characteristic corrosion-resisting properties in most environments. The steel must contain at least 10.5% chromium for this passive layer to form.

There are many modes of corrosion; atmospheric corrosion is one of the most widespread causes of metallic degradation. It occurs as a reaction of a metal to its immediate environment. It is generally predictable and measurable, and therefore can be designed into a structure by adding thickness factor. Examples of successful use of stainless steel in a corrosive environment are the railway electrification masts in Gqeberha. The line runs from the harbour along the coast to the North End, moving inland. During high tide and windy conditions, the masts are constantly exposed to sea spray. The metal of construction used is utility ferritic stainless steel grade 3CR12®. Installed in 1982, these masts have seen very aggressive coastal environmental conditions. But after 40-plus years in operation, the structure is still in pristine condition, with minimal thickness reduction experienced. This proves that the longevity of the product and minimal maintenance are critical attributes to consider when selecting materials of construction.

Stainless steels are known for their superior corrosion resistance and are mainly used in the bare mill finish without the need for additional protective coating systems to enhance corrosion protection – hence cementing them as the lowlife-cycle-cost metals of choice.■