Material Engineering The (Process) Chain Breaks at the Weakest Link

Editor: Dominik Stephan

Anyone who works in the chemical industry is familiar with the problem: aggressive media and high temperatures put vessels, valves, fittings and internal components under extreme stress. It is important to select the right material to ensure that the equipment does not become the expected point of failure in the process chain.

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(Picture: © James Steidl - / Milton Beychok; [M]-Anetzberger)

In 1912, Clemens Pasel, who worked in the Patent Department at Krupp, delivered a short document to the Imperial Patent Office in Berlin. The formula, which the archive worker handed to the Prussian clerks, was for something which researchers throughout Europe had regarded as the “holy grail”: a non-rusting steel.

For years, the up and coming chemical industry had been searching for a material that would withstand the enourmous stress of production. Conventional steel became brittle and developed cracks when exposed to aggressive media and thermal stress. A highly resistant material would have huge advantages …

Steel for Chemicals – A Though Challenge

It is hardly surprising that European material researchers kept an eye on each other. German and English foundries in particular vied to develop new alloys with the armament race looming in the background. Sending a minor office worker like Pasel was a clever move by Krupp Research Director Professor Benno Strauß. The company’s “King of Steel” was responsible for a number of successful alloys. His crowning achievement however was corrosion-resistant Nirosta, the first austenitic stainless steel. Containing 23 % chromium and 9 % nickel, it is very similar to V2A which is still used today. The new material made its breakthrough in the chemical industry a year later. Reactors made of austenitic stainless steel were used for the first time when Haber-Bosch ammonia synthesis started up at BASF.

A broad portfolio of stainless steel is currently available to the chemical industry. Alloys containing chromium, nickel, molybdenum, manganese or niobium are used for various media and types of mechanical stress. Which is best depends on the application. Steel with chromium added can readily be hardened and has good resistance to heat deformation. Alloys containing nickel have better corrosion resistance and are easier to weld.