Regular inspection is important to verify the integrity of in-service pipeline in the petrochemical industry. Early detection of flaws is therefore essential to ensure the continued safe operation of pipeline. In generally, Conventional ultrasonic for thin-walled small-diameter pipes has limitations due to regulation requirements, efficiencies, lack of permanent results and repeatability. In many cases, the preferred method of inspection is radiographic testing, however there are many obvious shortcomings for radiographic detection. The aim of this work was to propose appropriate phased array ultrasonic scan plans that were able to achieve the following: reduce the inspection times, improve defect detectability and sizing, and reduce human intervention, which will reduce workforce radiation uptake. Ultrasonic simulation using CIVA and experimental verification for thin-walled small-diameter pipe with flaws that were carried out to determine the most appropriate phased array probe and its detection capabilities in this paper.