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To prevent various types of brittle damage that may occur in hydrogenation reactors, it is effective to take the following measures during operation, startup and shutdown, or when shutting down the reactor for in-service inspections. For reactors manufactured from steels with high sensitivity to temper brittleness (such as 2¼Cr-1Mo steel), a hot-state start-up and shutdown procedure should be employed during restarts and shutdowns after the first operation. During the shutdown process, it is advisable to have a holding period at 300°C to 350°C to allow as much of the hydrogen absorbed during operation to escape from the vessel walls, thereby minimizing the residual hydrogen content in those walls. The requirements of the operation manual must be strictly followed during startup and shutdown. To prevent the formation of large thermal stresses, it is recommended that the heating and cooling rates during startup and shutdown not exceed 25°C–30°C/h and 25°C/h respectively. Unplanned shutdowns and restarts should be avoided as much as possible. This is effective in protecting the reactor and reducing hydrogen-induced delamination of its surfacing layer. When the top manhole is opened for reactor installation or shutdown inspection, appropriate protective measures must be put in place to prevent rainwater from entering the reactor. Take appropriate measures to prevent stress corrosion cracking due to polythiic acid in the austenitic stainless steel parts within the device.