Abstract: A heat exchange surface in reactors and/or heat exchangers of installations for the conversion of hydrocarbons and other organic compounds at high temperatures in the gaseous phase. According to the invention, the metallic surfaces coming into contact with the organic substances are treated at a temperature of 300 to 1000.degree. C. over a period of 0.5 to 12 hours with a mixture of a silicon- and sulfur-containing product and a dry gas flow which is inert with respect to the silicon- and sulfur-containing product. The invention is further directed to a process for producing a catalytically inactivated metallic surface in chemical reactors and/or heat exchangers.

Abstract: The invention relates to the protection of tubular reactors or heat exchangers against coke formation in plants for converting hydrocarbons and other organic compounds at high temperatures in the gaseous phase. The problem in such plants is that the usual steam/air cleaning processes for removing coke deposits lead to an increase in the catalytic activity of the material surfaces, which in turn shortens the service life of the plants. The object of the invention is to substantially reduce coking and to maintain the long-term passivity of steels for long operational periods.