What standard steel pipes should be used for the furnace tubes in coking heaters?

Delayed coking? Cr9Mo

The radiation section generally uses Cr9Mo, while the convection section uses 316L due to the issue of naphthenic acid corrosion.

For the 1.2 million tons per year delayed coking unit in the million-ton oil refining and million-ton ethylene project, the pipeline material used in the radiant section of the delayed coking heater’s tubes is P9(1Cr9Mo), while the pipeline material for the convective section is 1Cr5Mo; the specifications are Φ127×8 mm； The pipe material in the convection section is 1Cr5Mo, with specifications of Φ127×10 mm and Φ152×8 mm ； The furnace tubes in the high-temperature radiation section of the heating furnace are made of P9 material; those in the shielding section are also of P9 material. The feed to the heating furnace is high-sulfur, low-acid residue oil, which tends to coking when operated at high temperatures, and sulfur corrosion is a concern due to the presence of sulfur in this medium. Therefore, P9 material is used to enhance oxidation and corrosion resistance ； The furnace tube material in the convection section and steam section is 1Cr5Mo ； The designed medium flow rate for the furnace tubes in the convection section, shroud section, and radiation section is 22,500 kg/h. The designed inlet temperature is 320°C, the designed outlet temperature is 500°C, the designed inlet pressure is 2.5 MPa, the designed outlet pressure is 0.55 MPa, and the hydrostatic test pressure is 6.3 MPa.