Material selection for hydrocracking units in refineries under high-temperature sulfur and high-temperature sulfide corrosion conditions

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1. For pipelines whose medium temperature is 240°C or higher and that are exposed to corrosive media containing active sulfides, the impact of high-temperature sulfide corrosion on material selection must be taken into account. Under normal circumstances, the total sulfur content in the medium and the operating temperature of the medium should be used as parameters to estimate the corrosion rate of candidate materials using McConomy’s method; thereafter, the main material should be selected based on the following principles: ① Taking into account the temperature distribution, the high-temperature oil pipelines of the entire system should be divided into several temperature zones, and an appropriate material should be chosen for each zone ； ②Carbon steel and 1Cr5Mo should be given priority; 1Cr9Mo material can be used when necessary ； ③For large-diameter pipes, it is advisable to use carbon steel + stainless steel composite sheets to roll the steel pipes. 2. When the flow velocity of the medium is 30 m/s or higher, materials resistant to erosion and corrosion should be considered.