Equipment thermal tightening
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Which parts require thermal tightening, and what are the requirements for such tightening? The high-pressure threaded fastening ring heat exchangers in our diesel hydrogenation unit have been out of service for a long time; is thermal tightening necessary before restarting them, and if so, how should it be carried out? What precautions should be taken? The seals in the turbine section were removed during the shutdown period; is it necessary to perform thermal tightening when restarting, and what considerations should be taken into account during thermal tightening?
On our end, it’s mainly the high-pressure steam pipes that require heat
Each device has its own specifications for heat tightening, also known as the specified torque. The relevant materials for these devices are documented and available for reference; heat tightening should be carried out in accordance with the specified torque values, and it is not allowed to use a hammer to apply force manually
Operate according to the specified curve (increasing temperature and pressure); heat tightening is generally not required. However, if there is a material leak during startup, heat tightening must be carried out immediately. It is recommended to use hydraulic wrenches, which should be kept on hand at all times.
Since metals expand when heated and contract when cooled, tightening bolts when it’s cold should be more effective than doing so when it’s hot. Why is that? ? ?