New Delhi: Delhi govt will strictly enforce the mandatory hydro-test requirement for CNG vehicles and won’t allow refuelling if the certificate has expired or can’t be shown, senior officials said.The hydro test, required to be carried out every three years as per Rule 35(1) of Gas Cylinder Rules (2025 Amendment), checks whether a cylinder can safely withstand the high pressure at which CNG is stored in it. During the test, the cylinder is emptied, filled with water and subjected to very high pressure to check for leaks, cracks or swelling.In CNG vehicles, gas is stored in cylinders at 200-250 bar pressure. Regular use, pressure changes and exposure to road vibrations can affect the cylinder over time, making periodic testing important for detecting structural damage that may not be visible during a routine inspection, said an official.The hydro-test certificate serves as an official document confirming that the cylinder has passed the prescribed high-pressure water test and is considered safe for use.The move follows the explosion of a truck’s CNG cylinder during refuelling on Aug 19, killing three pump workers and seriously injuring three others.Indraprastha Gas Limited (IGL) has already launched a special drive at its CNG stations and asked personnel to verify the validity of hydro-test certificates before refuelling, said the official. The periodic test is essential for every safe journey, said an IGL official, urging vehicle owners to get their cylinders tested on time and keep the certificate in the vehicle. Vehicle owners have been asked to get their cylinders tested at a centre approved by Petroleum and Explosives Safety Organisation as per the Rules.
