Fracture and deformation behaviors of tee pipe with local wall thinning

Monotonic four-point bending tests were conducted using tee pipe specimens having local wall thinning. The effects of local wall thinning on the fracture behaviors of tee pipes were investigated. Local wall thinning was machined on the inside of pipes in order to simulate metal loss due to erosion corrosion. The configurations of the eroded area were l = 100 mm in eroded axial length, d/t = 0.5 and 0.8 in eroded ratio, and 2θ = 90° in eroded angle. The area undergoing local wall thinning was subjected to either tensile or compressive stress. It was found that the type of fracture could be classified into ovalization, local buckling, and crack initiation, depending on pipe shape, eroded ratio, and stress at the eroded area. Fracture behaviors of the tee pipes were compared with those of straight pipes. Three-dimensional elasto-plastic analyses were also carried out using the finite element method, which was able to accurately simulate fracture behaviors.