How to provide heat tracing for a section of the phthalic anhydride production line, and what considerations should be taken?

First, regarding the material used for manufacturing the heat tracing tube: the outer tube is made of carbon steel, while the inner tube is made of stainless steel. The length of the exposed portion of the tube at the heat tracing joints should be kept as short as possible; if the exposed length is too long, it should be wrapped with metal sheeting before being insulated, and copper tubes can be used for additional heat tracing when necessary. Pressurization is required before operation, and both the inner tube and the jacket need to be pressurized. As long as there is a slight internal leak in the jacket, the phthalic anhydride inside will solidify once the flow of material stops. At that time, it will have to be taken down to clear the blockage, which is very troublesome. After the heating element is installed, since there are definitely dirt particles such as welding slag inside the jacket, purging is required; it is best to disconnect the steam trap and use a drain line for purging, and then activate the system after the purging is complete. If it doesn’t blow through, tap it more forcefully; there might be impurities blocking it. If that still doesn’t work, saw it into sections and check where the blockage is located. The new tube needs to be checked regularly; simply rubbing it with phthalic anhydride will do. Under normal conditions, phthalic anhydride will melt when it comes into contact with heat. Because the strainer can still get clogged easily; it’s just sufficient to remove the filter screen and clean it.