Capabilities and Limitations of Radiography and Phased Array Ultrasonic Test in the Detection of subtle welding defects Fereidoon MAREFAT 1 , M.Reza FAGHEDI 2 , A.Reza KHODABANDEH 3 , M.Reza AFSHAR 4 , Ali AMADEH 5 , Afshin YOUSEFI 6 1 Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Quality Coordinator- Mapna MD2 Co. Tehran, Iran; Phone: +989111373228, Fax: +982182987814; Email: marefat_f@mapnamd2.com, marefat_msa@yahoo.com 2 QC&QA Manager – MapnaMD2 Co. Tehran, Iran; Email: faghedi@mapnamd2.com 3 Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; Email: metallurgy@srbiau.ac.ir 4 Department of Materials Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; Email: mafshar@srbiau.ac.ir 5 School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Iran; Email: amadeh@ut.ac.ir 6 Laboratory Managers – Iran Welding Research and Engineering Centre; Tehran, Iran; Email: a8688_yousefi@yahoo.com Abstract Not only progression of technology will not be conducive in development of construction processes ranging from forming and welding processes as well as development of advanced materials without modern processes of inspecting about the reliability of the final product, but also may cause irreparable damages. In order to do so, the modern method of Phased Array Ultrasonic, having potential abilities, has been invented to be substituted with radiographic inspection which has been a common but old method of assessing quality of production and welding of different parts. In this article, we are to check the possibility of substituting the new approach (Phased Array Ultrasonic) with the former laborious method in some power plant connections. And for this purpose we have focused on each methods weak points i.e. inability of radiography to detection of delicate but dangerous flaws especially in the thick sections and ultrasonic weakness in detection of surface flaws. Keywords: Non Destructive Test (NDT), Phased Array Ultrasonic Test (PAUT), Radiographic Test (RT), Artificial Defects, Gas Tungsten Arc Welding (GTAW), Shielded Metal Arc Welding (SMAW) 1. Introduction Non Destructive Tests (NDT's) are referred to the techniques which are often used to distinguish defects and disorders of materials. In most cases, they are unique methods to get information about perfectness of both parts and processes. As the matter of fact, it is not easy to contrast between what called as physical properties of material and what maybe imperfections and thus, it causes to fail in detecting imperfections and defects as well as wrong consideration of some information as a defect. Moreover, personal errors always interact and affect whole process. A proper application of NDT leads to enhance information which helps for the healthy and correct application of part and equipment. In contrast, any wrong result will make an incorrect picture of health and integration of product which may bring non- compensable detriments [5].Nowadays, regarding growing rates of industrial requirements, NDT procedures are rapidly developing. These requirements are able to be categorized as: 1- Reducing the total prices SINCE2011 Singapore International NDT Conference & Exhibition , 3-4 November 2011