On the basis of research results, rational alloying, and structural stabilization, the Central Research
Institute for Structural Materials developed three types of heat-resistant and heatproof alloys with superior
operating characteristics for use in various components of radiant coils – the low-temperature part and the
high-temperature part of the tubing system, and the mounting and suspension hardware. Since the tubing
system in radiant coils is a welded structure, welding materials (wire and electrodes) were also developed
for installation and repair of such coils. The alloys developed have different levels of alloying elements,
thereby enabling the alloys to be selected for use based on operating conditions. This rational approach to
use of the new materials reduces the funds required for fabrication and repair of radiant coils.
The functionality of structural materials in high-temperature radiant coils for various purposes is a current issue due
to the severe conditions under which they are being used: in units for direct reduction of iron, units for production of hydrogen, units for production of ammonia, and units for production of ethylene.
Radiant coils in high-temperature oil synthesis plants also operate under extremely severe conditions: operating temperature range 900–1100°C, gas flow velocities 200–300 m/sec, and pressure 0.25–0.37 MPa. Since the working medium for
these units consists of unsaturated hydrocarbons, carbon precipitates out on the inside walls of the tube system during the
reaction to obtain the end product (especially in the case of ethylene); this then leads to the formation of coke on the walls
of the tube system, which sharply reduces heat transfer and causes localized overheating of the tubes.
All the above leads to premature damage (failure) of radiative coil tubing-system components, thereby reducing the
service life of high-temperature plants, and leads to higher material costs for repair and restoration operations.