Why is Q245R used in catalytic reactors instead of Q345R?

The material is selected based on factors such as the properties of the materials and catalysts, as well as the reaction conditions. For example, consider factors such as the reactor’s corrosion resistance, as well as its pressure and temperature tolerance. Then compare the differences between these two materials and you’ll understand.

Cost, my friend – when the process requirements are met, it’s better to choose the option with a lower cost

Materials with lower costs are selected based on factors such as temperature, pressure, and volume during the reaction process, ensuring safety at the same time. 245R was previously called 20g, and 345R was previously called 16MnR

In H2S stress corrosion environments, Q245R exhibits better corrosion resistance than Q345R, and it has a lower material cost.

Choose the one with a lower cost if performance is sufficient

This post was last edited by lupg on 2020-4-8 at 18:16. 1 Starting in the 1990s, as the quality of catalytic raw materials declined, weld cracks appeared in the regenerators and subsequent equipment (three-spinners) of some companies; by the end of the 1990s, such cracks had become a common problem. 2 Due to the good catalytic efficiency, many users were forced to carry out welding repairs while continuing to operate, which posed a significant safety threat. To this end, various companies and their headquarters conducted a lot of analysis and came up with various countermeasures using their unique approaches. 3 At that time, the causes of damage were mainly stress corrosion resulting from the condensation of nitric and sulfuric acids in the flue gas; the main countermeasures involved reducing the strength of the container’s metal material, performing heat treatment on the welds to relieve stress, and increasing the temperature of the vessel walls. In-service equipment was mitigated through appropriate measures; subsequent designs for catalytic converters reduced the use of high-strength 16MnR in favor of 20G. Due to the reduced allowable stress of the metal, a slightly larger wall thickness was chosen.

When both materials are available, it’s a matter of cost

In certain situations, attention should be paid to the effect of the medium on these two materials. In a wet H2S stress corrosion environment, for low-carbon steel and carbon-manganese steel, Ceq≤0.40%. Due to its lower carbon equivalent, Q245R exhibits better resistance to wet H2S stress corrosion compared to Q345R.