In view of the importance of the national standard tee in the safety assessment of pressure pipelines with defects due to its complex structure, many structural parameters and limit load research, the difficulty of establishing analytical solutions of stress and limit load of tee with local thinning defects and the limitation of theoretical derivation can not well simulate the mechanical model and boundary conditions. In this paper, the method of finite element analysis is used to obtain the formula of plastic limit load on the basis of accumulating a large number of plastic limit load data of tees with different geometric parameters, so as to explore the calculation method suitable for engineering application. In view of the existing problems, the following research contents are determined on the basis of previous research results:
(1) Finite element method is used to analyze and calculate the ultimate load of flawless welded tees under internal pressure, and the influence of geometric parameters of national standard seamless tees on the plastic ultimate internal pressure is studied, so as to simplify the influence factors of plastic ultimate internal pressure, and on the basis of a large number of finite element calculations, the plastic covering area is established. Limit internal pressure database.
(2) Based on the established database of plastic limit internal pressure of defect-free welded carbon steel tee, the engineering estimation formula of plastic limit internal pressure of defect-free tee is fitted, which is suitable for engineering application and has high precision.
(3) The plastic limit internal pressure of welded tees with local thinning defects under internal pressure is studied by numerical analysis and calculation.