The test specimens were made of SA 333 Gr. 6 carbon steel and SS 304 LN grade stainless steel. The carbon steel pipes were of 12² nominal outer diameter and nominal thickness of 22 mm. The stainless steel pipes and elbow specimens were of 6² nominal outer diameter and nominal thickness of 14.2 mm. The circumferential notch was located on the base metal for carbon steel pipes whereas for stainless steel pipes the circumferential surface notch was located on base metal in a few specimens and weld metal in others. The notch was located in the base metal at intrados, extrados or crown location for stainless steel elbows. The orientation of the notch on elbow specimens was either circumferential or axial.
Crack growth data was acquired during the fatigue tests at regular intervals of loading. Alternating Current Potential Difference, Ultrasonic and Phased Array techniques were employed for crack detection and sizing. Surface crack growth measurements were made using a video microscope. Beach mark loading technique was also employed for crack growth profile validation. Fatigue crack growth tests were carried out under various loading conditions namely, vibration loading, vibration and torsional loading, etc. Same FCG tests were also conducted on elbows in water environment. In addition, fracture tests were conducted on pipes under static monotonic loading under in-plane bending. The extensive experimental investigations have resulted in better understanding of the behaviour of piping components and helped in generating valuable fatigue crack growth data under different environmental and loading conditions which will be very useful for integrity assessment of power plant components.