recent improvements regarding …...recent improvements regarding ultrasonic crack inspection of...
TRANSCRIPT
PPSA 2017, Aberdeen, November 8
RECENT IMPROVEMENTS REGARDING ULTRASONIC CRACK INSPECTION OF PIPELINES
Herbert Willems, Thomas HennigNDT Global, Germany
OUTLINE
� Inspection Task
� Inspection Technology
� Influence of Pipeline Medium
� Resolution & Inspection Speed
� Enhanced Depth Sizing
� Summary
2Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
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OBJECTIVE OF INLINE CRACK INSPECTION
Detection & Sizing of
� Crack-like weld anomalies (ERW, SAW, DSAW,....)
� Fatigue cracks
� Stress corrosion cracks (SCC)
with axial or circumferential orientation and
� Length ≥ 20 mm (0.8 in) resp. ≥ 30 mm (1.2 in)
� Depth ≥ 1 mm (0.4 in) resp. ≥ 2 mm (0.8 in)
���� Provide reliable input data for crack assessment!
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
CRACK INSPECTION USING 45°°°°SHEAR WAVESModelling Result
Modelling using FD-method (ultrasonic frequency: 4 MHz)
4Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
INSPECTION PRINCIPLE45°°°°Shear Wave / Pulse-Echo Inspection
works for most liquids: crude oil, products, water, liq uid gas....min. depth: 1 mm / 0.04 in , min. length 25 mm / 1 in (opt. 20 mm / 0.8 in)
5Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
Axial
Radial
Circumferential
σσσσH σσσσA
STRESSES IN PRESSURIZED PIPE
σσσσH ≈≈≈≈ 2 σσσσA
Axial cracking
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
Axial
Radial
Circumferential
σσσσH σσσσA
σσσσA > σσσσy
+ (cyclic)bending stresses
Circ. cracking?
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STRESSES IN PRESSURIZED PIPE
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
INSPECTION TYPES
Axial Inspection
InspectionGeometry
Sensor Carrier(section)
Circumferential Inspection
InspectionGeometry
Sensor Carrier(section)
8Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
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CIRCUMFERENTIAL SCC DETECTED IN STEEP TERRAIN
C-Scan
Girth Weld
SCC
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
OUTLINE
� Inspection Task
� Inspection Technology
� Influence of Pipeline Medium
� Resolution & Inspection Speed
� Enhanced Depth Sizing
� Summary
11Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
INSPECTION PRINCIPLEAngular Dependency of Corner Reflection
Inspection Geometry
crack
Signal Amplitude vs. Refraction Angle
Angle of Incidence α (water)0 5 9 13 17 20 23 25 26 27
Angle of Incidence α (propane)0 2.5 5 7 9 11 12.5 13.5 14 14.5
12Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
MEDIUM ATTENUATIONOn-Board Recording
13Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
OUTLINE
� Inspection Task
� Inspection Technology
� Influence of Pipeline Medium
� Resolution & Inspection Speed
� Enhanced Depth Sizing
� Summary
14Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
THREE DIMENSIONS OF RESOLUTION
3. Depth Resolution
2. Axial Resolution
1. Circumferential ResolutionHigher number of sensors
Shorter Shot Distance
Larger Data Format
15Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
Flow direction
Cir
cum
fere
nti
ald
irec
tio
n
AXIAL CRACK INSPECTIONImprovement of Scanning Grid
UCx (1.5mm x 5mm)UC (3mm x 10mm)
16Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
IMPROVED CIRCUMFERENTIAL RESOLUTION
Flow
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UC UCx
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
RUN 1 (UC)
RUN 2 (UCx)
IMPROVED CIRCUMFERENTIAL RESOLUTION
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B-scans from two different inspections, same anomaly
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
INSPECTION TYPE
AXIAL RES.(mm)
CIRC. RES. (mm)
MIN. LENGTH(mm)
MAX. SPEED*(m/s)
Axial Crack Inspection
UC 3.0 / 1.5 10 25 / 20 4.0 / 2.0
UCx 1.5 5 20 2.0
Circumferential Crack Inspection
UCc 1.5 10 30 2.0*at given axial resolution
RESOLUTION & MAX. INSPECTION SPEED
19Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
OUTLINE
� Inspection Task
� Inspection Technology
� Influence of Pipeline Medium
� Resolution & Inspection Speed
� Enhanced Depth Sizing
� Summary
20Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
CRACK DEPTH SIZINGDepth Dependency of Corner Reflection
EDM notches in 10 mm plate
saturationlevel
-30
-20
-10
0
0 2 4 6 8 10
Am
plitu
de /
dB
Depth / mm
Modelling (ext.) Exp. (ext.) Exp. (int.)
21Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
CRACK DEPTH SIZINGSaturation Effect (schematic)
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CRACK DEPTH SIZINGIndirect Signal from External Crack (schematic)
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MODELLING RESULTCorner Echo & Indirect Crack Echo
A-Scan Crack
Surface
A-Scan Crack
Surface
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
CRACK DEPTH SIZINGCorner Reflection & ICE Signal (Modelling Result)
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CRACK DEPTH SIZINGReflections from External Crack (modelling)
0.5 s
1.5 s
1.0 s
Cornerreflection
Cornerreflection
Indirectcrack echo
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B - Scan
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
CRACK DEPTH SIZINGExample Circumferential Fatigue Crack
Surface Indication
Cross Section
Ultrasonic Signals
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
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CRACK DEPTH SIZINGICE Signal (Results from Pulltests with UCx)
axial crack inspection
0
-1
-2
-3
-4
-5
-6
-7
-8
-9
-10
± 1.3 mm
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
CRACK DEPTH SIZINGOld Specification vs. New Specification (Enhanced Sizi ng)
old new
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tolerance at 80% certainty: ± 1 mm / 0.04 in respectively ± 1.3 mm / 0.05 in
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
OUTLINE
� Inspection Task
� Inspection Technology
� Influence of Pipeline Medium
� Resolution & Inspection Speed
� Enhanced Depth Sizing
� Summary
30Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8
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SUMMARY
IMPROVEMENT BENEFIT
Enhanced axial resolution • More detailed crack profiles• Smaller minimum crack length
Enhanced circumferential resolution
• Increased POD & POI• Reduced risk of incomplete coverage• More accurate maximum reflection amplitude
Increased inspection speed • Reduced costs by avoiding loss of throughput during inspection run• Less operational interference
Enhanced depth sizing• Full wall coverage of crack depths• More accurate and less conservative crack assessment• Reduction of excavation costs
Online monitoring of medium properties
• Reduced risk of failed run due to change of medium properties during inspection
• Better data quality by adaptive signal gain
Copyright © 2016 | NDT Global PPSA 2017, Aberdeen, November 8