Structure Analysis And Safety Assessment Of Pressure Vessels

Pressure vessels work in pressurized situations, and they deal with the mediums of high temperature and flammable or explosive natures. Once an accident occurs, it will cause immeasurable damage, loss of human life and property. Liquefied gas container accidents can have a disastrous effect resulting in fire or explosion which can damage not only a large quantity of industrial and living facilities but also cause serious environmental pollution.The accidents of pressure vessels have a connection with deficiencies and cracks existing in the structure of the container. As research on container deficiencies and crack mechanisms continues, many existing problems remain unsolved. Examining the practical problems existing in the boiler and liquefied gas container, this article analyses 3-D transient temperature and the distribution regularity of stress of the vessel; as well as structural analysis of boiler and LPG pressure vessels with numerical and finite element methods which are based on heat transfer and heat elasticity theories. Research on safety assessment of pressure vessels is carried out, combined with their working character of boiler and LPG containers and based on changing regularity of temperature and stress and fatigue or crack theories.The work encompasses the following aspects: boiler drums, boiler evaporation pipes, liquefied petroleum gas (LPG) vessel in the flame environment and liquefied ethylene gas (LEG) cargo tank in a cryogenic state.The transient method is adopted systematically to calculate and analyze the temperature and stress field in various typical working processes in the boiler. The impact on stress caused by different temperature between upside and downside or between inside and outside of the boiler drum and its uneven temperature in parts is explored.On the basis of structure analysis combined with CTOD (crack tip opening displacement), this article will also calculate the total stress of dangerous areas and the annual development of the cracks in the drum and determines the crack critical size according to the crack tolerance of the materials.