the evolving ndt method of 3d laser scanning for inspection · (scan, analyze, report) • written...

NDT in Canada 2015 Conference

The Evolving NDT Method of

3D Laser Scanning for Inspection

David Mackintosh, Bryan Cornforth, Tom Taylor, Kerry Blevins, Samuel Langdon


Outline

1. Introduction to 3D scanning

2. Case example

3. 3D Scanning as an NDT method


Part 1

Introduction to 3D Scanning


Some Applications of 3D Scanning

• Inspection and damage assessment

• Measurement and verification

• Reverse engineering (‘scan to CAD’)

• Plants, facilities, and tanks (mid range)


Mid Range Laser Scanning

Typical specs:

• Range up to

150 m (500 ft)

• Completes

360° scan in

about 15 min.


Overview of

Mid Range Scanning

Tankdeformation strain analysis

Surge bin fill volume

Coke burner floor warpage

Documentation and measurement

of component damaged in

explosion


Creaform3D.com

Close-Range Laser Scanning

• Close range means

a few inches from

the surface

LaserScan3D

• The rest of this

presentation will

focus on close range


A Surface Scan Gives Information

• Compare this

surface to a

cylinder

Highlights:

• Corrosion

• Mechanical

• Manufacturing

imperfections


Example: Dent Assessment Software• Designed for on-site analysis by Level 2 technician

Post-processing for strain analysis:


Laser Scanning for Inspection

Strengths

• Non-contact: no part wear or damage

• High resolution (tens of thousands of points

per square foot)

• High accuracy available: some metrology-

grade scanners rated 1 in 10,000

(0.1 mm over 1 m, or 0.001 inch over 1 foot)

• Scan data can be imported for finite element

analysis


Laser Scanning for Inspection

Limitations

• Surface method only; needs reference surface

for analysis.

• Shiny or dark-coloured surfaces usually

require preparation (matte white)

• Bright ambient light can ‘blind’ scanner;

shading may be needed

• Cannot scan into sharp cracks

• Analysis often software-intensive


Ultrasonic Testing (UT) as a Partner

Technology to Laser Scanning

• Laser scanning and UT can be used together to

estimate depth of corrosion.

• Automated (scanning) UT has difficulty on

heavily corroded surfaces

• Spot UT (pencil probe) can provide check

points

• Laser scanner can cover entire surface at high

resolution, with verification from UT points.


Depth of Metal Loss on a Curve

?

• In software, a reference curve can be used to

measure depth

• With extensive corrosion, estimating the

reference curve is more difficult


Ultrasonic Thickness (UT) for More

Accurate Reference Surface

UT1

UT2UT3

UT4

UT5

Estimatedreferencesurface


Part 2

Case Example


A Sample Scanning Job,

from Start to Finish

• Fitness for service

assessment of

support legs on

storage sphere

• Scan data was used

to estimate

corrosion depth

• Job in Edmonton,

Canada, -9°C (16°F)


Surface at First Sight

• Before scanning, surface

was sandblasted to remove

coating and heavy rust.


Additional Debris (Ice) was

Removed from Surface

• Meanwhile, the scanner is in open air

being cooled to ambient temperature


Calibrate.Scan.


Ultrasonic Thickness (UT) Readings

• UT readings

used for

reference on

extensive

corrosion.

• Position of

each reading

is marked with

an optical

target


Scan Data


Analysis

Reference surfaceScan data


Report: Deviation plot


Report: Spreadsheet Grid of Depths

24


Part 3

3D Scanning as an NDT Method


Challenges of a New Technology

• Few codes and standards [MacKinnon, 2014]

• Advanced analysis software can be expensive

and complex

• Common perception of the technology as:

– easy

– automatic

– gives you all the info you need

– ‘laser’ = ‘accurate’


Elements of a Quality Program

• Training course

• Written requirements for certification

• Scanning reference blocks

• Benchmarking


Training and

Certification

• Syllabus

• Multi-choice exams

• Practical exams

(scan, analyze, report)

• Written requirements for

experience

hours


Training Course Outline

• 3D scanning: purpose, benefits, & limitations

• Laser safety (most laser scanners are eye-safe)

• Theory:

– Scanner principle of operation

– Optical properties of surfaces

• Field Practices

– Suitability of scanner for a given job

– Optimizing scan settings

– Sources of noise and inaccuracy

– Software analysis tools


Scanning Reference Block

Example:

• Portable verification

coupon for pipeline

corrosion scanning

• Coupon is scanned to

verify that the system

produces the correct

ASME B31G burst

pressure


Benchmarking

• Example: pit sizing test block

• Block is used to measure and verify scanner

performance on a range of pit sizes


BenchmarkingExample

• What is the narrowest pit (aspect ratio) that a

scanner can measure?

• Typical scanner viewing angles range from

15° to 30°.


Conclusion


3D Scanning

• 3D scanning: a powerful and rapidly-evolving

NDT method

• As with other methods, requires training,

experience, development, and an effective

quality program.


Thank you!

• Questions?


References and SourcesANSI/ASNT CP-105-2011, Standard Topical Outlines for Qualification of Nondestructive Testing Personnel, The American Society for Nondestructive Testing, Columbus, OH, 2011.

ASME B31G-2012, Manual for Determining the Remaining Strength of Corroded Pipelines, The American Society of Mechanical Engineers, New York, 2012.

ASNT, “Laser Based Profilometry Using Point Triangulation”, Nondestructive Testing Handbook, Second Edition: Volume 9, Special Methods, the American Society for Nondestructive Testing, Columbus, OH, 1995.

ASNT, Recommended Practice No. SNT-TC-1A: Personnel Qualification and Certification in Nondestructive Testing, The American Society for Nondestructive Testing, Columbus, OH, 2011.

Harding, K. "3D profilometry: next requests from the industrial viewpoint", Proc. SPIE 7855, Optical Metrology and Inspection for Industrial Applications, 785513 (November 11, 2010).

Kainat, M., Samer, A., Cheng, J.J.R., Ferguson, J., and Martens, M., “Identifying Initial Imperfection Patterns of Energy Pipes Using a 3D Laser Scanner”, Proceedings of the 9th International Pipeline Conference IPC2012, Calgary, Canada, September 24–28, 2012.

MacKinnon. D., Roe, G., "3D Imaging Standards: Where are we now?" 2014 SPAR International Conference, Colorado Springs, CO, April 17, 2014.

Mackintosh, D., Taylor, T., Bryant, G. "Field Experience and Best Practices for Laser Assessment of Pipeline Damage," NDT in Canada 2013 Conference, Calgary, Alberta, October 7-10, 2013.

Pfeffer, C., “The State of 3-D Imaging Standards”, Quality Digest, November 9, 2010.www.qualitydigest.com/inside/cmsc-article/state-3-d-imaging-standards.html.


Authors

Acuren Group, Inc.David Mackintosh, Edmonton, AlbertaBryan Cornforth, Calgary, AlbertaTom Taylor, Acuren Group Inc., Calgary, Alberta

Acuren Inspection, Inc.Samuel Langdon, Acuren Inspection, Inc., Cincinnati, OHKerry Blevins, Acuren Inspection, Inc., Cincinnati, OH

the evolving ndt method of 3d laser scanning for inspection · (scan, analyze, report) • written...

Documents