All about CNG Cylinder Hydro Testing and Compliance Plate


What is Hydro Testing of CNG Cylinder ? 

Hydro Testing also called as Hydrostatic Testing is a non-destructive test procedure to check cylinders for leaks, structural flaws, durability, and corrosion. This process checks cylinders structural integrity as well. An external and internal visual inspection of the cylinders are also performed.

This process tests the CNG cylinder for its pressure handling strength, to ensure safety. Hydro Testing are being done at government authorized CNG Hydro Testing Centres.

Process of CNG Cylinder Testing

As per gas Cylinder Rules, 2004 CNG cylinders are required to be tested periodically every 3 years.

Steps followed for testing of Cylinders: -

  • De-pressuring & Degassing of Cylinders
  • Valve opening and Internal Inspection.
  • Internal cleaning of cylinders.
  • Cylinder Wall Thickness measurement by Ultrasonic Thickness Tester.
  • Water Jacket method for Hydrostatic stretch testing.
  • Cylinder Drying, Internal / External Cleaning.
  • Test mark sign is used after testing the fitness of the cylinder.
  • Checking of Tare Weight
  • Internal / External Inspection (bulge, burn, dents, dig, cut, pit and line corrosion etc.)
  • Fixing of Valves
  • Assemble & Disassemble of CNG Cylinder / Cascades
  • Deliver the cylinder with Certificate and compliance plate if found suitable.

What is a Compliance Plate?

It is an aluminium plate affixed appropriately in your Car by Hydro Testing Centres, which indicates that cylinder is safe. Compliance plates are being checked at CNG stations before filling the CNG.

Who does Hydro Testing and gives you compliance plate?

You can find a list of government certified Hydro Testing centres as listed by Transport Department and IGL on their website. You can also reach out to to avail the services of Hydro Testing

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