After the first CO2 strippers were taken into operation having 316L Urea Grade heat exchanger tubes, it appeared that, short after the start up, these HP Strippers with 316L UG heat exchanger tubes were not resistant under the severe conditions present in a HP Stripper.

Upon that a new material was developed by Stamicarbon and Sandvik called x2CrNiMo25.22.2. The first Stripper with these 2RE69 tubes was already installed in the urea plant of UK Wesseling in (West) Germany in 1969 (picture). This material was and still is a favourite material in HP Strippers The measured corrosion rate in the heat exchanger tubes is average 0,05 to 0,06 mm per year on stream.