Fracture studies on carbon steel elbows having part-through notch with and without internal pressure

• Fracture studies were conducted on elbows with and without internal pressure.
• Effect of internal pressure on load carrying capacity of the elbows was studied.
• Ovalization of elbows under in-plane opening and closing moments was studied.
• Internal pressure reduced load carrying capacity of elbow with circumferential notch at intrados.

Elbows are one type of components widely used in various industrial applications in conventional and nuclear power generating plants, chemical processing plants and petroleum refineries. Due to the complexities of geometric structure, elbows are one of the piping components that are prone to failure in the piping system of nuclear power plants (NPPs). In service, the piping components are subjected to internal pressure in addition to bending loads, and the internal pressure is known to have significant effect on the load carrying capacity of these components. Hence, fracture studies were carried out on 406 mm diameter elbows with and without internal pressure. The investigations have shown that the location of notch plays an important role in the load carrying capacity of the elbows and their failure behaviour. The internal pressure reduced the load carrying capacity of the elbow when the notch was located at the intrados in circumferential direction and the behaviour is vice-versa when the notch was located at the intrados in an axial direction, when subjected to opening moment, in both the cases.

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