Local scorch marks on the jacket surface or darkening of the oil color during equipment operation are often related to surface load control and the flow state of the medium. Regarding the maintenance points of concern to technical engineers, the following is presented in a Q&A format.
A: Focus on checking the sealing condition of the wiring cavity, whether there is carbon deposit or scaling on the jacket surface, and whether fasteners are loose. For explosion-proof types, confirm that the flameproof surface is intact and the protection rating is maintained at IP54 or above. It is recommended to record the insulation resistance once a month; when it is below 1MΩ, shut down the equipment for troubleshooting.
A: The jacket-type structure supports core replacement without draining the medium. Before operation, cut off the power and wait for the jacket to cool below 50°C, then loosen the junction box and pull out the core. After replacement, check the cold-state insulation according to JB/T 12233-2015, and slowly raise the temperature to the working temperature to observe whether the current is stable.
A: For oil heating, it is recommended to control the surface power density at 1~3W/cm² to avoid carbonization caused by local overheating. For corrosive media, 316L or titanium alloy jackets should be selected, and the wall thickness should be checked regularly. Under high-temperature conditions, the thermal expansion allowance of the jacket must be calculated to prevent stress concentration at the flange connection.
A: If shut down for more than three months, measure the insulation resistance to confirm the moisture condition; check the wiring terminals for oxidation; carry out the first heating in stages, stabilizing for 30 minutes at each stage, and observe the deviation between the temperature controller and the actual measurement. If the medium contains water, first circulate at low speed to remove the water before energizing.
