Pressure mantle built in 1920 by Krupp, the German industrial giant, and was installed that year in the Ammonia Plant No. 1 at the Ludwigshafen ammonia plant. The pressure mantle consists of a long cylindrical pipe 13 metres long and approximately 1.7 metres in diameter and weighs around 70 tonnes. The interior of the mantle is several layers of laminated steel, and the central internal chamber is coated with low-carbon iron lining to prevent the leaching of carbon from the steel tubing, which would have made the steel brittle and fragile. At either end of the cylinder are flanges, which would have connected the pressure mantle to pipes to supply the reagents and catalysts for the Haber-Bosch process, and to take away the liquid ammonia for further processing. Haber-Bosch process pressure mantle 1913 to 1921