This paper aimed at carrying out a failure analysis on a typical gas pipeline in Niger Delta, Nigeria. The research analyzes the causes of failure of an existing pipeline which conveys 35MSCF/D of natural gas from the processing plant of marginal oil and gas field to a power generating station, 14km away. Non Destructive Testing (NDT) procedure, specifically, Ultrasonic Testing method was used to carry out the failure analysis on the pipe specimen. The pipeline thickness gauging alongside the flaw detention procedures carried out showed that the pipeline failed integrity test, therefore unfit for its intended purpose. The overall result shows that the major causes of the pipe failure are metallurgical/weld defect as well as corrosion along the welded line. The parameters obtained were used to compute the failure model for the pipeline.