Seamless Heat Exchanger Tube SA210 A1 ASTM A213T12 Q195 Q235 Carbon Steel

How to determine the central moment of the heat exchange tube?
The central moment of the heat exchange tube is generally not less than 1.25 times the outer diameter of the heat exchange tube, which is mainly considered:During expansion, the elastic deformation ranges between the pipe holes do not intersect; when welding, leave a certain distance between the welds of each pipe section to reduce the welding stress between them. For slot welding around the tube hole on the tube sheet, the central moment of 125% of the outer diameter of the heat exchange tube is already the lower limit, and more than 132% of the outer diameter of the tube can be taken when conditions permit; this value is greater than or equal to 25mm. For heat pipes, it is convenient enough to clean the tube bundle, but for heat exchange tubes with an outer diameter of less than 25mm, in order to facilitate cleaning, the clear distance between the tubes should be 6mm.
Why can the heat exchange tubes not consider the corrosion allowance?
The corrosion of the heat exchange tube definitely exists, but it is mainly concentrated in the pipe joints, and uniform corrosion is generally not the main problem; the heat exchange tube is a heat exchange element, if it is too thick, it will affect the heat exchange efficiency; the diameter of the heat exchange tube is very large. If it is small, the corresponding calculated thickness is also small, and the corrosion allowance is still there, but it is not as large as the shell, so its design service life is shorter than that of the shell; if the corrosion is serious, corrosion-resistant materials can be used. For example, some heat exchanger tubes are made of stainless steel, while the shells and heads of the shell side and tube side are all carbon steel; if the heat exchange tubes are corroded and penetrated, they can be replaced; The way to solve it, insist on using it until the next overhaul in order to replace the new heat exchanger.
What are the special requirements for heat exchange tubes?
The heat exchange tube is a pressure component. In addition to the material properties that it should have as a pressure component, the heat exchange tube itself has its own special requirements: high dimensional accuracy (outer diameter, wall thickness, length); material plasticity and toughness Good, especially for tube expansion, flanging and bending; welding performance of thin-walled tubes; low hardness value, generally lower than the hardness value of tube sheet; high test pressure.