Nurul Baini Ghazali creator author. text my 2025 2025 monographic eng xiv, 133 pages : illustrations (some color) ; 30 cm. + 1 CD-ROM The thesis describes the fatigue crack growth (FCG) behaviour of API 5L X65 gas pipeline surface cracks using S-version FEM. API 5L X65 is widely used in oil & gas for transportation of hydrocarbon gas and crude oil from upstream facilities to downstream facilities and end user such as power station, petrochemicals industries, transportation industries and residential. Beside to suit the purpose in term of chemical and mechanical properties, API 5L X65 is cost effective and have better strength compared to other material grade. Nowadays, the major concern of the engineering application is the material failure. Hence, the fatigue crack analysis needs to carry out to determine the fatigue life of a material. This is important as it is involving the human safety and lead to fatality. In this study, a method known as global-local overlay technique was used to predict fatigue behaviour, which involves two separate meshes, one for global (geometry) and one for local (physics) (crack) by using S-version Finite Element Method (S-version FEM). The pre-post program was used to model the FAST global geometry (coarser mesh) so called CentOS programming, which included the material and boundary conditions. As a result, the exact location of the local crack (finer mesh) will be defined, and the mesh control will be adjusted accordingly. The Paris’ crack model is used to predict the fatigue crack behaviour of this material. Local mesh was overlaid with the global mesh before the numerical computation to solve the engineering problem. The virtual crack closure-integral method (VCCM) was used to calculate the stress intensity factors (SIF). The most important result is the fatigue crack growth behaviour, which includes the crack depth (a), crack length (c), and stress intensity factors (SIF). The SIF value is important as it affect the crack growth. Then, the fatigue crack growth with 0.4 aspect ratio (a/c) is determined. After that, different a/c is used to compare the result obtained in S-version FEM with analytical solution in Newman & Raju 1979. specialized Nurul Baini Binti Ghazali Faculty of Mechanical and Automotive Engineering Technology Thesis (Master of Science) -- Universiti Malaysia Pahang – 2025 Includes bibliographical references Faculty of Mechanical and Automotive Engineering Technology Dissertations Universities and colleges Dissertations THE0010090 (Local) UMPSA 250522 20251125111043.0 eng