Air separation plant maintenance

Under the conditions of certain welding methods, welding materials, welding specification parameters and welding structure, the difficulty of obtaining high-quality welded joints is called steel weldability. Therefore, the weldability should be evaluated from two aspects of manufacturing and application. The weldability of process mainly refers to the possibility of various cracks in welded joints, which reflects the difficulty of manufacturing. Weldability of using mainly refers to the mechanical properties and special properties of heat resistance, corrosion resistance, low temperature resistance and fatigue resistance of welded joints, which reflects the reliability of use.

When the same pressure is reduced, the temperature drop of throttling is far greater than that of expansion. This is because the gas does not work externally during throttling, but when the molecular spacing increases, the potential energy of molecules increases, and the kinetic energy decreases correspondingly, reflecting the decrease of temperature. The expansion refrigeration not only increases the potential energy between molecules, but also makes external work to push the impeller to rotate or push the piston to move. All these energies need to reduce the kinetic energy of molecules, so the molecular kinetic energy decreases more and the temperature drop is larger.