Measuring Pipe Deformation with Ring Laser

Owned by Ernest Döbeli
Last updated: Apr 20, 2023 by Daniel Steiner
4 min read

This article explains how the operator must proceed to properly record a video clip with the ring laser equipment.
The end part describes how to position the calibration rings or the calibration points. For more details please read the manual to the module LaserScsan.

Instructions

Range of operation
• Investigation of pipe line systems, which have to satisfy high demands on material stability.
– Hydropower plants (stability examination of high pressure pipes)
• Warranty assessment of high performance drainage systems for objects like…
– Tunnels and bridges
– Highways
– Airport Runways

Prior to the survey

• Pipe cleaning: removal of floating deposits
• Removal of encrustations to reduce light reflexions on pipe wall or pipe ground
• Block water flow in order to get the pipe ground visible

Run the survey

 

Prior to the scan
• Center camera head
• Set Laser ring diameter to 75% of image height
• Set recording format to MPEG2 in order to increase accuracy of measuring results
• Place the whole length of the calibration bar within the camera view angle
• Cover the manhole in order to avoid light intrusion at the beginning of recording a video clip

During the scan
• Switch off the light and text display: only the laser ring must be visible
• Increase the light intensity of the laser ring at larger diameters accordingly
• Decrease image luminosity in order to get disturbing red sparks disappeared
• Scan with a constant low speed (max. 17 cm/sec) in order to avoid jerky movements of the camera head.
• Keep the camera head centered during recording
• Record a sequence showing the entire calibration bar (100 mm - 600 mm)

Center the camera

Scan procedure

Speed <= 17 cm/sec

 

Record calibration bar (horizontal)


Record calibration bar (vertical)

Calibration bar: scale invisible

Calibration bar: scale visible

Laser ring with light intrusion

Laser ring with light reflections


Laser ring too big

Laser light too weak

Laser ring not centered

Water flow not blocked

Settings: OK

Set calibration points

Show calibration rings

After the scan

 

Multi-Laser; scan pipe deformation

Multi-Laser; measure pipe deformation

 

You always need a video clip with the corresponding index file (time-distance file); without this the LaserScan module cannot run the scan process.

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