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What are the key points of tower top pipeline design? 1) The operating temperature at the bottom of the tower is generally higher, so when arranging the tower bottom pipeline, its flexibility should meet the requirements of relevant standards or specifications. Especially when the extraction pipe at the bottom of the tower is connected to the pump, the pipe should be short and have few turns, and must be flexible enough to reduce the stress on the pump nozzle. The extraction line from the bottom of the tower should be led outside the tower skirt or base. It is strictly prohibited to install flanges, instrument joints and other pipe fittings inside the tower skirt. The extraction pipeline from the bottom of the tower to the bottom pump must not have a "bag shape" on the horizontal pipe section and should be "step by step" to avoid cavitation in the bottom pump. The partition valve on the extraction pipe should be as close as possible to the tower body and easy to operate. ； (2) Unless it is an auxiliary reboiler, or two or more parallel reboilers are operated at the same time, and their heat load is required to be adjusted within a wide range, the pipeline from the bottom of the tower to the reboiler is generally not suitable for valves. When the tower bottom kettle type reboiler is equipped with a centrifugal pump, the elevation of the reboiler should meet the effective NPSH required by the centrifugal pump, and at the same time, the static pressure head formed by the height difference between the liquid level at the bottom of the tower and the liquid level in the reboiler is sufficient to overcome the pressure loss in the downcomer, reboiler and riser pipe. Therefore, the layout of the pipeline should meet the flexibility requirements, and the pipeline should be short and have fewer elbows. (1) The top pipelines generally include top oil and gas, vent and safety valve outlet pipelines. The vent pipe at the top of the tower is generally installed at the top of the horizontal pipe section at the highest point of the oil and gas pipeline at the top of the tower, and should comply with the requirements of fire protection regulations. ； (2) The medium in the oil and gas pipeline at the top of the tower is generally gas phase. The pipe diameter is larger and the pipe should be as short as possible. It should be "step by step", bag-shaped pipes should not appear, and it should have a certain degree of flexibility. ； (3) Each pipe along the tower needs to be equipped with a load-bearing bracket on the upper part and a guide bracket at an appropriate position to prevent the nozzle from being overstressed ； (4) The oil and gas pipelines at the top of the fractionation tower are generally not insulated, only anti-scalding. ； If the pipeline goes to multiple cold exchange equipment, in order to avoid biased flow, it should be arranged symmetrically ； (5) When there is a two-stage condensation at the top of the tower, the pipeline arrangement should make the condensate flow automatically step by step. The oil and gas main pipe and the condensation road inlet branch pipe should be arranged symmetrically to ensure uniform flow. ； (6) When the tower top pressure is controlled by thermal bypass, the thermal sleeve pipe should be insulated and kept as short as possible. Its regulating valve should be installed on the upper part of the reflux tank, and the pipe should not be "bag-shaped" to avoid liquid accumulation. ； (7) The oil and gas pipeline at the top of the pressure reduction tower is directly welded to the tower opening instead of flange connection to reduce leakage.