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Ultrasonic Flaw Detection in CNG Cylinder.

Ultrasonic Testing uses high-frequency sound waves to detect internal cracks, voids, and wall thinning—ensuring CNG cylinders meet safety and compliance.

Hintech Team
Hintech TeamDecember 4, 2025

Ultrasonic Flaw Detection in CNG Cylinder Calibration — Why It Matters?

Ultrasonic Testing (UT) is a Non-Destructive Testing (NDT) technique that uses high-frequency sound waves (typically 0.5–15 MHz) to detect flaws inside solid materials. It’s widely used in aerospace, oil & gas, power, and CNG cylinder calibration because it can identify internal defects without damaging the component.

⚙️ How it Works

  • Probe/Transducer generates ultrasonic sound waves that enter the cylinder wall.
  • Waves travel through the material and reflect (echo) when they hit a boundary (like the back wall or a defect).
  • The returning echoes are received by the probe and displayed on a screen as peaks (A-scan display).
  • By analyzing the time of flight and amplitude of echoes, inspectors determine:
    • Thickness of the material
    • Size, location, and orientation of flaws
    • Whether the defect is surface-breaking or subsurface

✅ Why UT for CNG Cylinder Testing?

CNG cylinders operate at 200–250 bar pressure or 3000-3600 PSI, even microscopic cracks can cause leaks or explosions. UT flaw testing is used to:

  • Detect cracks, voids, inclusions, and corrosion pits invisible to the eye
  • Measure wall thickness to detect thinning or erosion
  • Identify fatigue or stress-related defects caused by repeated pressurization
  • Verify that the cylinder material is uniform and free of hidden weaknesses

📊 Values Obtained in UT

  • Thickness readings (in mm) → ensures cylinder meets PESO/ISO minimum thickness requirements
  • Defect depth & size → quantifies severity of cracks or voids
  • Defect location → surface, mid-wall, or back wall
  • Echo patterns → type of defect (crack, porosity, inclusion, lamination)

🎯 Advantages of UT (as an NDT Method)

  • Non-destructive: Cylinder can continue to be used if it passes
  • High sensitivity: Detects defects as small as 0.1 mm
  • Quantitative: Provides measurable defect size & depth
  • Immediate results: Inspectors get real-time readings
  • Safe & reliable: No radiation, unlike X-ray testing

👉 UT flaw detection acts as the second safety net after hydrotesting. While hydrotest ensures the cylinder can withstand pressure, UT ensures the material itself is flawless. Both together guarantee safety, compliance, and longer cylinder life.