A CNG cylinder has to go through several rigorous testing procedures, including burst testing, impact testing, fire testing, ultrasonic testing, and hydro testing. Among all, hydro testing plays a major role in verifying the structural integrity and high-pressure withstanding capability of any CNG cylinders. But what is it, how is it done, and how often should CNG cylinders be hydrotested? If you have these types of burning questions in your mind, stay with us and explore this comprehensive blog post written solely around CNG cylinder hydro testing. Keep reading!
A] What is Hydro Testing in CNG Cylinders?
Hydro testing, also known as hydrostatic testing, is a crucial testing procedure that ensures the structural integrity, safety, and reliability of CNG cylinders. CNG cylinder hydro testing is a non-destructive procedure that utilises high-pressure water to verify the ability to withstand high pressures in normal working scenarios. It is a mandatory safety measure that involves several inline steps, including cylinder inspection, pressurisation, visual inspection, and certification, which are described in detail in the process section below.
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B] Hydro Testing of CNG Cylinders: The Process
1. Valve Removal and Visual Inspection
Before starting the testing procedure, the valve of the cylinder is removed and visually inspected to find any gross visual defects or deformations. If it is observed, the cylinder is sent back to the manufacturing units.Â
2. Filling With Water and Applying Pressure
After removing the valve, the cylinder is filled with water and then pressurised. Pressure is increased gradually until it reaches a predetermined test pressure, usually greater than the cylinder’s working pressure.
3. Holding and Observing for Leaks/Deformation
After achieving test pressure, the cylinder is held at that pressure for a specific duration to reveal leaks, weak welds, cracks, and other structural flaws. If the cylinder has revealed any deformities during hydro testing, it is sent back to the manufacturing units for repair or reconstruction.
4. Certification
At last, if the cylinder passes the hydro test, it is certified by PESO, which authorises the cylinder to be safe and used in normal working conditions. The certification shows that the cylinder has been tested thoroughly and is safe for daily use.
C] How Often Should CNG Cylinders Be Hydro Tested?
As per the Gas Cylinder Rules, 2004, every CNG cylinder should be hydrotested every 3 years, or depending on the local regulations. It checks for the cylinder’s structural integrity and helps identify potential leaks and damages. Doing so leads to the safe operation of CNG cylinders throughout their lifespan. In addition, authorised refuelling stations may restrict individuals from refuelling CNG if the test is not done within the predefined timeline.
D] Validity of Hydro Tested CNG Cylinders
Every CNG cylinder must undergo hydro testing every 3 years, depending on regulatory norms. You can check the validity by looking at the test date stamped on the cylinder’s neck or shoulder, often marked with colour coding (e.g., red for expired, green for valid). Using a cylinder past its validity date can lead to legal issues, rejected insurance claims, and serious safety hazards. Regular hydro testing ensures the cylinder maintains its structural integrity under pressure. Always verify your cylinder’s hydro test date to stay compliant with safety standards and government regulations.
E] Where and How to Get Your CNG Cylinder Hydro Tested
To hydrotest your CNG cylinder, visit an authorised testing centre approved by your local transport or petroleum authority. These centres follow strict safety and testing protocols outlined by the Petroleum and Explosives Safety Organisation (PESO) in India. The turnaround time is usually one to two working days. Always ensure you get a valid test certificate and sticker after the process. Testing your CNG cylinder at a certified facility is essential for road safety and continued insurance coverage of your CNG-powered vehicle.
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Conclusion
A hydro test for CNG cylinders is a mandatory safety process required to verify the structural integrity and ability to withstand the needed pressure. It ensures the CNG cylinder remains safe and operational throughout its lifespan without any structural issues.Â
Rama Cylinders is a leading CNG cylinder manufacturer in India, offering cost-effective and robust CNG cylinders to domestic as well as aboard facilities. Our CNG cylinders go through rigorous testing procedures, including the hydro test, to ensure they are extremely secure and able to withstand harsh industrial or driving conditions. If you are looking for nationally and internationally certified CNG cylinders, contact us today!
FAQs
Hydro testing in CNG cylinders is a mandatory safety process used to assess the cylinder’s ability to withstand high pressure over time. During hydro testing, the cylinder is filled with water and pressurised to levels higher than its working pressure to check for leaks, bulging, or structural weaknesses. It ensures that the cylinder is safe for continued use.sed natural gas used to fuel vehicles. It works by safely storing CNG at around 200-250 bar pressure, which is then regulated and fed into the engine for combustion.
Hydro testing is important because CNG cylinders operate under very high pressure (up to specific test pressure bar as per standards). Over time, due to regular use and exposure to environmental elements, the metal may weaken or corrode. Hydro testing verifies the cylinder’s strength and ensures that it won’t fail or explode under pressure, thus protecting lives and property.
CNG cylinders must be hydro tested every 3 years, depending on the type of cylinder and government regulations. The test date is usually stamped on the cylinder’s surface.
If a CNG cylinder is not hydro tested on time, it becomes illegal to refill it. Additionally, using an untested cylinder can void vehicle insurance and pose serious safety risks, including potential explosion or leakage.
