RESUMEN
A compression tank is normally made like round column shape to the middle part and plate shape in both sides. These kinds of tanks are usually designed to resist inner pressure but if the inner pressure is too high the tank will be exploded and some pieces can severe damage to human. If the shape of corner is about 90 degrees the stress will be very high at corner. So this kind of tank have been manufactured as smooth round corner even though its cost. Although smooth round type of corner, there is always some area of high level of stress and it is very difficult to calculate exactly because of complicate shape of corner. In this case study, here we introduce the FEM method to calculate the exact solution and compare the result with engineering fomula. The edge of tank was modeled like actual edge of tank and the critical inner pressure is 2.5 kg/cm2. This result is proven by engineering formula and we knew that this FEM method would be trustable to calculate a plenty of delicate problem whether the structures have original defect or not.