What are the causes of stress in heat exchanger equipment and how can it be eliminated?

The original poster asked: “What are the factors that cause stress in heat exchanger equipment in chemical plants, and how can it be prevented and eliminated?” Should I ask for your advice? Different types of heat exchangers have different failure stresses. In tubular heat exchangers, the stresses are generally thermal differential stress and welding stress ； Spiral plate stress is the welding stress and the stress generated during the rolling process.

Thank you very much. Most of the heat exchangers used in our equipment are tubular types, with the majority being of the fixed-tube-plate type.

It may not be correct; it’s just for your reference. I thought the main stress on heat exchangers was thermal stress, resulting from pulses in the system fluid, changes in fluid pressure, and variations in the pressure difference between the inside and outside of the heat exchange tubes, as well as forces such as gravity and torque transmitted through the external piping. The welding stress has been eliminated after the equipment is manufactured; even if any remains, it is minimal.

The stress in a tube sheet heat exchanger consists of two components: one resulting from the misalignment in axial deformation between the heat exchange tubes and the shell side cylinder (caused by pressure and temperature differences), as well as from the misalignment in radial displacement and angular deformation of the tube sheet, the tube side cylinder, and the shell side cylinder (also caused by pressure and temperature differences); and the other component being the overall bending stress and overall membrane stress generated on the tube sheet. Another part consists of the local stresses caused by pressure and local temperature differences at the tube sheet tube bridges and at the joints between the tube sheet and the heat exchange tubes [China’s GB151 standard and the U.S. TEMA standard focus primarily on overall bending stresses, while Germany’s AD code focuses mainly on local stresses]. For thick tube sheet structures, the overall bending stress is the dominant factor ； In the thin tube sheet structure, the overall membrane stress and local stress in the middle of the tube sheet are the dominant factors, while the overall bending stress at the edges of the tube sheet is the key factor (the influence area of edge stresses is wider for thick tube sheets and narrower for thin tube sheets).

The main cause is thermal stress resulting from temperature differences, and the best solution is to install expansion joints!