Experimental fracture studies on carbon steel elbows 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.
• Various data acquired during the study include load, LLD, CMOD, ovality of the elbow.
• Circumferential notch at intrados significantly affects elbow load carrying capacity.

Pipe bends or elbows are commonly used components for nuclear power plant piping system. In service, these piping components are subjected to internal pressure in addition to bending loads and the internal pressure is known to have a significant effect on the load carrying capacity of these components. Hence, a systematic study was carried out to investigate and quantify the effect of internal pressure on the fracture behaviour of elbows used in nuclear power plant piping system. Fracture studies were conducted on five 219 mm diameter carbon steel elbows with and without internal pressure under in-plane opening moment. The investigations have shown that the presence of a circumferential notch at the intrados has a more detrimental effect on the fracture behaviour of the elbow, when compared with the presence of an axial notch at the intrados. It is also found that internal pressure plays a significant role in reducing the ovalization.