Case of stress corrosion failure of instrumentation pipeline fittings caused by mutual interference between production units

Thread Content

Case of stress corrosion failure of instrumentation pipeline fittings caused by interactions between production units. Example: A chemical plant built a new production unit, whose instrumentation pipelines were constructed using copper pipes and brass fittings. After several weeks of use, the accessory was damaged due to stress corrosion cracking. The investigation found that not far upwind of this newly installed facility, there is another production unit that periodically releases small amounts of nitrogen oxides into the atmosphere. This creates the environmental conditions for stress corrosion cracking to occur in brass fittings with residual stress. Analysis: This case involves the location selection for a production facility. There are corrosive interactions between the various devices within a single production unit, as well as between different production units. This mutual influence is mainly caused by the leakage and emission of corrosive gases. Measure: Therefore, when locating production facilities, it is necessary to avoid building them downwind of those that release corrosive gases. Production facilities that emit corrosive gases should be built as far as possible away from areas where air circulation is poor or where there is a lack of wind, to ensure that these corrosive gases can disperse quickly. At the same time, it is necessary to avoid pollution of nearby factories and residential areas. Equipment that emits corrosive gases should be installed outdoors as much as possible. If it needs to be built inside a factory building, the structure of the building should be as simple as possible to facilitate natural ventilation; it is best designed to be open or semi-open. Within the same building, the areas where corrosive gases are emitted and those where non-corrosive gases are emitted should be separated, to prevent the equipment in the non-corrosive areas from being damaged by corrosive gases and wastewater. To ensure the proper operation of instruments, areas where instruments are concentrated, such as control rooms and power distribution rooms, should not be located on floors where liquid corrosive media are handled, and they should also be kept away from equipment that emits corrosive gases.