Proceedings of the ASME 2013 Pressure Vessels & Piping Division Conference PVP2013 July 14-18, 2013, Paris, France 1 Copyright © 2013 by ASME PVP2013-98040 FRACTURE ASSESSMENT OF X65 STEEL PIPE WITH THROUGH-WALL CRACK UNDER PURE BENDING A-H. I. Mourad Mechanical Engineering Department, Faculty of Engineering, United Arab Emirates University B. O. Box. 15551, Al-Ain, UAE. Tel: +719-3- 7135116 Email: ahmourad@uaeu.ac.ae J. Altarawneh Mechanical Engineering Department, Faculty of Engineering, United Arab Emirates University B. O. Box. 17555, Al-Ain, UAE. Email: jafery711@yahoo.com A. El Domiaty Mechanical Engineering Department, Faculty of Engineering, United Arab Emirates University B. O. Box. 17555, Al-Ain, UAE. Email: alyeldmiaty@eng.suez.edu.eg ABSTRACT Stable crack growth emanated from circumferential through-wall crack in X65 steel pipe under pure bending was evaluated. Seamless carbon steel pipes grade X65 PL5 with an inner diameter of 42.9 mm and an outer diameter of 60.3 mm were used in the present experimental work. This type of pipes is of common use in piping systems of gas and oil industry. Pipes of different circumferential crack depths were tested. J-R curve was used to characterize the nonlinear fracture behavior of the through-wall crack pipe. Variation of J with crack growth, crack surface area and deflection of the pipe were obtained. J- integral-crack growth curve was used in the calculation of critical crack size based on the Jc value measured in our previous experimental work by testing full scale pipe made from the same material. The length of crack at unstable crack growth is also determined. Both critical and instability crack sizes can be used for fracture assessment of X65 steel pipes. NOMENCLATURE a Crack length COD Crack opening displacement E Young’s Modulus G, Strain energy release rate J J-integral K Stress intensity factor J C , K C, G C Fracture toughness K IC , J IC Plane strain fracture toughness P Applied load EPFM Elastic plastic fracture mechanics LEFM Linear elastic fracture mechanics σ y Yield strength σ u Ultimate strength  Poisson’s ratio INTRODUCTION The structure integrity assessment of gas pipe line, nuclear reactor pressure vessels, conventional pressure vessels might be evaluated according to fracture mechanics models such as CEGB R6, BSI 6493,WES 2805 and ASME X1. These methods are based on deterministic approach where the fracture toughness parameters(K 1c and J 1c ) are essential input values to evaluate and assist the structure fracture integrity [1-15] Analytical methods for elastic-plastic fracture analysis of circumferential through-wall-cracked (TWC) pipes subjected to pure bending are well-developed. Brust et al. [1] and Rahman et al. [2,3] have summarized several methods for predicting the J-