Strictly speaking, stainless steel pipe and carbon steel pipe cannot be stacked together. Because the materials of carbon steel pipe and stainless steel pipe are different, in a humid environment, if carbon steel pipe and stainless steel pipe are stacked together, it is very simple to have a chemical reaction, and then damage the protective layer of stainless steel pipe, resulting in rust of stainless steel pipe. If different steels are stacked together and touched, potential difference will occur, resulting in electrochemical corrosion, especially when there is ponding, the electrochemical corrosion rate between stainless steel pipe and carbon steel pipe will be accelerated.

Just like the principle of the battery, the direct conversion of chemical energy into electrical energy in the chemical battery is due to the oxidation recovery reaction inside the battery. In order to avoid electrochemical corrosion and carburization of stainless steel pipes, it is best not to pile them together. However, at room temperature, when carbon steel and stainless steel are bonded, carburization will not occur immediately. The mottled corrosion on the stainless steel pipe will appear only after a certain period.

End reinforcement of stainless steel pipe fittings. The establishment of three-dimensional finite element model of stainless steel pipe fittings is studied. Through stress analysis, it is found that there is obvious stress concentration on the compression end face of wound pipe fittings under axial pressure

Establishment of three-dimensional finite element model of stainless steel pipe fittings. Through stress analysis, it is found that there is obvious stress concentration on the compression end face of wound pipe fittings under axial pressure. Therefore, it is predicted that the edge effect of compression end face of pipe fittings will lead to the decrease of axial compression strength of pipe fittings. The axial compression strength of strengthened and unreinforced pipe fittings at the end is quantitatively calculated through the three-dimensional finite element model, It is concluded that the axial compressive strength of end reinforced pipe fittings is significantly higher than that of unreinforced pipe fittings.

The thrust support of space vehicle refers to the main bearing structure on the vehicle to transfer the large thrust generated by the engine from one structure to another. It is generally composed of stainless steel pipe fittings, stainless steel joints, end frames, end plates and other components. Stainless steel pipe fittings are the main high load main bearing components of thrust support. They are usually made of metal materials with high quality. The results show that the end strengthening of stainless steel pipe fittings can effectively reduce the negative impact of end effect on axial compressive strength, and the axial compressive strength can be increased by more than 30percent.