Spiral Pipe stress corrosion cracking causes and preventive measures

Spiral steel construction and family life is a common pipe, which shine in many industries. Here's what the spiral pipe stress corrosion cracking causes and protective measures.

Spiral Pipe Stress corrosion cracking is a lag time-related damage, which is completely similar to delayed cracking and hydrogen. Stress corrosion cracking is a low-stress brittle fracture. Spiral Pipe stress corrosion only in certain circumstances take place, only exists stress (especially tensile stress) only when the stress corrosion cracking. This stress can be applied stress, T or introduced during welding and processing the residual stress corrosion products can also be caused by the action of the expansion wedge stress. Stress corrosion cracking is a petrochemical equipment, especially oil pipes with spiral steel pipe common cause of failure. Due to stress corrosion cracking occurred unpredictability, so the petrochemical industry, the biggest hidden dangers. In the petrochemical and nuclear industries such as equipment, most of the stress caused by stress corrosion cracking is caused by the residual tensile stress, it is often superimposed on stress at work. Mainly from the device residual stresses produced during the welding residual stresses. Stress corrosion cracking is a necessary condition for coexistence of tensile stress and corrosive media, the tensile stress is an important condition for stress corrosion.

Currently, the project is widely used welding cooling after annealing treatment to eliminate residual stress, while cooling after welding residual stress is an important process, this approach is not only a waste of energy and easy to produce larger welding residual stresses. Heat treatment after welding is a new technique to eliminate the residual stress. Preheated before welding the material to a heat treatment temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the stress corrosion resistance of metals. Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Post weld heat treatment can effectively improve the spiral pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant.

Besides, the spiral steel pipe is mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of 20 key products. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube.