عنوان مقاله [English]
Considering day to day increase in the cost of the gasoline for Iranian customers; the interested for using dual fuel automobiles are increasing. It is common using steel CNG vessels in Iranian dual fuel cars. Nowadays; there are millions of CNG vessels with more than 10 years of commissioning time in Iran. Recently, periodic inspection regulations are issued by the Iranian Standard bureau which is mandatory for taxi services. In this regulation, visual inspections are considered and it is recommended using ultrasonic inspections and/or hydraulic tests for critical vessels. Because of the importance of the topic for the safety of the citizens, this paper dedicated to investigate the statistics of the CNG vessels and their most common defects in country. In addition, the periodic inspection procedure of the Iranian regulations is compared with international counterparts. According to the discussion, inspection measures which considered by the Iranian standard bureau are enough and useful for standard CNG vessels; however, more than 25% of all CNG vessels in Iran are manufactured in nonstandard manners and they need more inspection measures. It seems that reducing of the inspection period from 36 months to 24 months will be of value.
 Fred F. Lyle, Jr. “Evaluation of the Effects of Natural Gas Contaminants on Corrosion in Compressed Natural Gas Storage Systems-Phase II”, Report Prepared by Southwest Research Institute 6220 Culebra Road San Antonio, Texas 78284, 1989.
 Hien Ly, “Effects of Natural Gas Composition Variations on the Operation,
Performance and Exhaust Emissions of Natural Gas - Powered Vehicles”, NGV Conference, 2002.
 U.S. Department of Energy Alternative Fuels Data Center http://www.afdc.energy.gov/vehicles/natural_gas.html
 مهدی ظهور، سعید صفار، محمد حسن صدفی طهران، طراحی مخازن گاز طبیعی فشرده (CNG) تمام فلزی برای خودروها، کنفرانس ملی مهندسی ساخت و تولید،
 ISO 11439:2013 Gas cylinders - High pressure cylinders for the on-board storage of natural gas as a fuel for automotive vehicles.