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Pressure vessel is the equipment widely used in the industry field. The equipment usually works in the pressure condition,and the contact medium is always perishable or more inflammable explosive materials and in high temperature. Once the accident,it will cause incalculable losses to people’s lives and property. Because of negligence or medium corrosion during carriage, installing or operating, there might appear many corrosion defect pits in the surface the container.Pit corrosion defects will make the structure discontinuity and stress concentration in surface of pressure vessel. Because of the complexity of the working environment, the pressure vessel might crack or craze, which would affect the bearing capacity and life length of the pressure vessel badly. Therefore, the mechanics analysis and safety assessment of the pressure vessel with pit corrosion defects is very important and necessary.Pit corrosion defects belong to body defect, which is not easy to analyze the stress with conventional methods. In this paper, the author used large-scale finite element analysis software to carry on stress calculation and analysis of pit corrosion defects in the surface of pressure vessels, in different directions, different quantity, and conditions. Meanwhile, the author discussed the affection of defects of pit corrosion to stress distribution in different conditions, that is, the interference between the pit corrosion effects. And draw the following conclusions: (1)The pit defects of pressure vessel make the stress concentration, which has affects the safe operation of pressure vessels badly.(2)The coefficient of stress concentration of double ring pits is increasing with the increased center distance of the two pits, decreased firstly, then increased and finally become constant. When the two pits are tangent, the stress concentration coefficient is minimum.(3)The coefficient of stress concentration of double axial pits is increasing with the increased center distance of the two pits, increased firstly, then decreased and finally become constant. When the two pits are tangent, the coefficient of stress concentration coefficient is maximum. Therefore, double axial pits are more danger than ring arranged.(4) In all situations, when pits distance increases to be certain, that is (L≥3.0), there almost no influence between pits.(5) When the space reached to be the certain degree, that is no great influence between each pit, the influence to the coefficient of stress concentration is minimum with the increasing number of pits.(6) The pits in axial are more danger than that in ring, which is need to be paid more attention to.
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