SINERGI Vol. 22, No.1, February 2018: 19-23 DOAJ:doaj.org/toc/2460-1217 DOI:doi.org/10.22441/sinergi.2018.1.004 . G. Priyandoko, Non-Destructive Leak Detection in Galvanized Iron Pipe 19 NON-DESTRUCTIVE LEAK DETECTION IN GALVANIZED IRON PIPE USING NONLINEAR ACOUSTIC MODULATION METHOD Gigih Priyandoko Department of Electrical Engineering, Faculty of Engineering, Universitas Widyagama Jl. Borobudur, No. 35, Malang, 65142 Indonesia Email: gigih@widyagama.ac.id Abstract -- Non-destructive testing is a wide group of analysis techniques used in science and industry to evaluate the properties of a structure without causing damage to it. The main objective of this project is to carry out an experiment to detect leakage in a pipeline using nonlinear acoustic modulation method. The nonlinear acoustic modulation approach with low frequency excitation and high frequency acoustic wave is used to reveal modulations in the presence of a leak. The pipe used in this experiment was galvanized iron pipe. The experiment is started with the experiment of an undamaged specimen and followed by the experiment of a damaged specimen with a manually applied leak. The results obtained are being observed and the difference between the specimen without leak and with leak can be distinguished. The distance between the leak and the distance of the outlet detected is nearly accurate to the exact location which is a leak at 4.0 m and outlet at 6.0 m. Therefore, the results demonstrate that leakage can be detected using nonlinear acoustic modulation, and proved the objective of distinguishing the difference between the results of a specimen without leak and with leak has succeeded. The damage detection process can be eased with the knowledge of the signal features. . Keywords: Non-destructive testing; Nonlinear acoustic modulation; Leak detection INTRODUCTION Recent developments in pipeline systems have heightened the need for a study about the pipe defect detection using ultrasonic guided wave method. In recent years, several studies have focused on defect detection in pipeline systems because it is very important used extensively all over the world to transport and distribute natural gas, crude oil, water, and other easy-flowing products. Indeed, in the process of continuous transportation, gas pipeline leakage cannot be avoided because of the corrosion of pipe walls (Arwati and Sianipar, 2018; Jarvis at. al., 2016), third-party interference (Liang, 2012) aging of the pipes (Vargas-Arista at. al., 2007), and so on. Therefore, leakage detection and localization are one of the paramount concerns of pipeline operators and researchers all over the world (Priyandoko and Fun, 2015). Many researchers have argued that Non- destructive testing (NDT) is a wide group of analysis techniques used in science and industry to evaluate the properties of a material, component or system without causing damage. NDT is a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research. Common NDT methods include ultrasonic, magnetic-particle, liquid penetrant, radiographic, remote visual inspection (RVI), eddy-current testing, and low coherence interferometry. According to K Haller (Sohn at. al., 2014), damage can be monitored in many ways. The choice of composite materials is no longer restricted to specific applications. In other fields, using these new materials as innovation tool and performance rising of their products such civil engineering. It is important first to have the best possible knowledge about these materials in somehow to monitor any changes in these properties and consequently their influence on the structure behavior (Lakhdar at. al., 2013; Li and Xu, 2013). Plastic pipe is a good material because of high resistance, light, cheap and long-life span. Therefore, plastic pipes usually are used to transport gas, water, and chemicals. In general, plastic pipes are widely used in metal or concrete pipes. Due to the material being immune to water corrosion and highly resistant to fouling, it is also being considered as a replacement for stainless steel in safety-critical applications in nuclear power stations (Assunção at. al., 2013). According to Carvalho et. al. (2008), researchers have spent an ample amount of time, investigations and researched on non- destructive test techniques. As much as during the setting up phase during their useful life, these techniques are used as a method to assess engineering structures and system (Cheng and Tian, 2011). Crack inspection is a valuable non- destructive test (NDT) method in many industries. The crack inspection method is useful, which