A new and unique bench-scale unit is presented to simulate high temperature corrosion of alloys for
radiant coils in Petrochemical Plants. This unit is developed and dedicated for the examination of
samples at steam cracking conditions: e.g. high metal temperatures/lower gas temperatures, low
residence times and a gas mixture which corresponds to the composition within the outlet tube of a
radiant coil. The oxide layers formed during the start-up of a cracking furnace are examined for different
temperature profiles. Different surface conditions of the inner tube surface as well as the catalytic coke
formation on oxidized surfaces are investigated. This provides valuable information on the amount and
location of catalytically active sites formed on the oxide layer. Furthermore, in order to evaluate the
oxide layer stability of different alloys after several runs, samples are exposed to controlled coking and
decoking cycles under various conditions. The new test rig also allows the introduction of feed
contaminants or reactive elements into the process gas for testing their specific influence on materials
deterioration. All these features enable tailor - making tube materials specific to the coil design and the
operating conditions, in order to optimize the benefits of precise material selection.
Exemplary test results of conventional and experimental alloys are presented.
Keywords: Alumina, carburization, centrifugally cast alloy, chromia, coking, corrosion, high temperature
alloy, hydrocarbon, ethylene pyrolysis, oxidation, oxide scale