The material used to make pressure pipes for hot water boiler pressure vessels is metal plates. During the manufacturing process, metal plates are subjected to welding, rolling, cooling and other process procedures. The temperature of each procedure will change. If the temperature is too cold or overheated, metal materials will be produced. crack. Higher heating temperature causes the crystal to oxidize or melt to produce over-burn cracks. If the heating temperature exceeds the critical temperature of the metal, over-heat cracks will occur. After welding for a long time, cold cracks will occur. Cold cracks that form for a long time are concealed and cannot be easily detected. Hot cracks can oxidize or melt crystal boundaries, and overheated metal cannot withstand deformation. These cracks cause huge hidden dangers to hot water boiler pressure equipment.
The formation of creep cracks is due to the changes in temperature and stress. With the increase of the use time, the creep cracks of pressure pipes of hot water boiler pressure vessels will occur due to damage. The main areas where such cracks are formed are the locations where the stresses of the pipes and headers are concentrated, and the surface of the pipes that are overheated and swelled. At the same time, the equipment will deform, the material structure will be damaged, and they will be separated from each other. The creep crack develops into a crack zone, where the main crack is centered and a large number of cracks are distributed on both sides. There are various numbers of holes in the damaged area of the device with peristaltic cracks. These holes are not regularly connected, and the shape is mostly rice grains or ovals. The propagation direction of the creep crack is along the crystal boundary.
Cracks in the inspection of hot water boiler pressure vessels and pressure pipelines must be prevented in advance and dealt with in a timely manner to increase the safety factor of hot water boilers, reduce the possibility of safety accidents, eliminate hidden cracks in a timely manner, and reduce the loss of citizen life and property.
