guided wave ut - grupotergolaf.com · features detection of internal or external metal loss...
Post on 28-Jan-2020
2 Views
Preview:
TRANSCRIPT
Guided Wave UT
Guided Wave
Ultrasonic
Testing
New Tool Developments
• Rapid screening for In-service degradation
• Reduction in costs of gaining access
• Avoid removal of insulation or coating
• Ability to inspect inaccessible areas
– i.e clamps and cased or buried pipes
• 100% coverage
Guided Waves
Conventional UT versus LRUT
Weld
Metal loss
Metal loss
FlangeConventional
Transducer
Localised Inspection
Weld
Metal loss
Metal loss
FlangeGuided wave
transducersGuided Wave
100% Inspection
Features
Detection of internal or external metal loss
Sensitivity
• Metal loss down to 3% of pipe wall cross-section
• Reliable detection of 9% metal loss flaws
• Now able to discriminate clock position
Discrimination between flaws, pipe features, welds, casing supports, etc.
Longitudinal accuracy better than 1”
New Beam Focusing (Helps with Flaw Discrimination)
New C-SCAN Imaging (Visual Presentation of Circumferential Extent)
New Software System for Improved Analysis• Multiple Distance Decline Curves
• Select locations for multiple focusing
Long
range
Short
range
Surface condition Geometry Contents
Bare metal Straight lengths Gas
Smooth well bonded paint
Fusion bonded epoxy Attachments Liquid
Light pitting
Heavy pitting
Plastic, e.g. PVC Branches
Buried (earth or sand)
Bitumen coated Multiple
bends
High viscosity
Concrete coated Flanges
Performance Summary
Some Limitations of LRUT
Geometric features such as Elbows, Flanges, Tees, Welded
Supports, socked welds, etc will attenuate or totally absorb the
LRUT signal.
Additional LRUT locations are need before and after every
elbow to guaranty 100% coverage.
Focus only works in straight sections . It does not work after
elbows.
LRUT signal do not travel after flanges.
Some Limitations of LRUT
Big Tees or branches absorbs tremendous energy. Therefore
additional test locations are required before and after these
features.
It is not the right tool to detect isolated pin holes.
Signal to noise ratio decreases when testing buried pipes in
presence of heavy coatings or fluids. This reduces the
probability of detection of small indications.
LRUT does not provide a reading of the remaining wall / wall
thickness at the location of the indication.
General Description Sensitivity
9% Anomaly(not to scale)
Pipe cross section(100%)
3% Anomaly(not to scale)
Each quadrant = 25%Each Clock position ~ 8%
An approximation of the
cross section area Loss can
be given by:
The total CSL is then equal
to the sum of all the defect
present on the same cross
section (12% in this case)
pipepipe
defectdefect
ThicknessRadius
DepthLengthCSL
2
• Road and river crossings
• Power plant tubing
• Risers
• Offshore topsides pipework
• Jetty lines
• Jetty Supports
• Refinery pipework
• Chemical plant pipework
• Tank farm link lines
• Sphere legs
• Pipe bridges
• Spiral welded pipe
• Austenitic stainless steel
• Sprinkler systems
• Lamp-posts
Applications
Examples of Application
Road Crossings Buried Pipe
Sphere Support Leg Gas Pipelines
Teletest Focus Unit
Integrated Battery – 12 Hrs
Integrated Air Pump
Auto System Check
Rugged System
Easy to Transport
Features
Diameters – 1.5" to 48"
100% Coverage
Multi-Mode Modules
• Torsional & Longitudinal
• True Beam Focusing
Test Range
• Typical ±90 Ft.
• Ideal conditions ±350 Ft.
Productivity
• Typical 1,000 Ft. per day
Service Temperature up to +260°F
Advantages
Easy to use unit and tool design for
quick data collection
Multimode – Longitudinal and torsional
wavemodes on one tool
Focusing – Defect distribution around
circumference “one-click” away
User friendly interface with report
manager generator
Minitest
Advantages:
1.5-4” Diameter Pipes
1.5” Thick Collar
3-ring Torsional
Light Weight Design
Modularize (1/2” Changes)
Limitation:
No Beam Focusing or Multi-
Mode Functionality
Collar design
Robust composite construction
Integrated clamp and bladder
Collars link for >24”
Multimode
Lightweight
Cost efficient
Easily Transported
New Software
Automated set-up
Fast and reliable defect detection
Simultaneous Multimode Shots
Simplified Analysis
Multiple DAC Curves
On-site MS Word report generator
<15 min data collection
Defect only detected using Longitudinal
waves
Torsional: No defects detected using T mode
• Longitudinal: both the pipe end and the defect
could be identified
FOCUS
-0.5
0
0.5
1
0
15
30
45
60
75
90
105
120
135
150
165
180
195
210
225
240
255
270
285
300
315
330
345
Applying the appropriate
correction factors allows a
concentration of energy
(focus) at a specific angle
for a given distance from
the transducer.
Benefits of focusing
Focusing allows the energy to be
concentrated where the defect is,
increasing sensitivity and giving
position and size information
Focal Spot – Actual measured shape
0
0.25
0.5
0.75
1
0
15
30
45
60
75
90
105
120
135
150
165
180
195
210
225
240
255
270
285
300
315
330
345
Specified target shape function Numerically predicted shape Actual Measured Shape
Small
sidelobes
predicted
Similar
sidelobes
Main lobes all at
correct angle and
shape
Focus – Benefits
Improved Sensitivity to smaller defects
Better call/no call information
Improved prioritisation of calls
Ability to find angular position of defects
Improved presentation possibilities for results
Directionality data from focusing
DefectWindowed time
domain of interest
Windowed time
domain of
interest
180o
0
6
0.5
2.0
1.0
2.5
1.5
3.5
4.0
3.0
0
0.26
0.33
0.25
0.75
0.75
0.7
0.63
3.13
0o
45o
90o
135o
225o
270o
315o
Focused at z= 32.8 ft.
Non Directional response from a weld
180o
0
6
0.5
2.0
1.0
2.5
1.5
3.5
4.0
3.0
0
2.80
3.75
2.8
2.50
2.25
3.4
2.50
2.70
0o
45o
90o
135o
225o
270o
315o
Unfocused - 3% notch in 16” pipeUnfocused result
0
50
100
150
200
250
0.0
1
0.2
3
0.4
6
0.6
8
0.9
1
1.1
3
1.3
6
1.5
8
1.8
1
2.0
3
2.2
6
2.4
8
2.7
1
2.9
3
3.1
6
3.3
8
3.6
1
3.8
3
4.0
6
4.2
8
4.5
1
4.7
3
4.9
6
5.1
8
5.4
1
5.6
3
5.8
5
6.0
8
6.3
6.5
3
6.7
5
6.9
8
7.2
7.4
3
7.6
5
7.8
8
8.1
8.3
3
8.5
5
m
sig
nal
am
pli
tud
e
Notch position
Pipe endInitial pulse
Focused at NotchFocused result
0
50
100
150
200
250
0.0
1
0.2
3
0.4
6
0.6
8
0.9
1
1.1
3
1.3
6
1.5
8
1.8
1
2.0
3
2.2
6
2.4
8
2.7
1
2.9
3
3.1
6
3.3
8
3.6
1
3.8
3
4.0
6
4.2
8
4.5
1
4.7
3
4.9
6
5.1
8
5.4
1
5.6
3
5.8
5
6.0
8
6.3
6.5
3
6.7
5
6.9
8
7.2
7.4
3
7.6
5
7.8
8
8.1
8.3
3
8.5
5
m
sig
nal
am
pli
tud
e
Initial pulse
Notch signal
Pipe end
Focused in Line and at 90° to Notch
0
50
100
150
200
250
0.0
1
0.2
3
0.4
6
0.6
8
0.9
1
1.1
3
1.3
6
1.5
8
1.8
1
2.0
3
2.2
6
2.4
8
2.7
1
2.9
3
3.1
6
3.3
8
3.6
1
3.8
3
4.0
6
4.2
8
4.5
1
4.7
3
4.9
6
5.1
8
5.4
1
5.6
3
5.8
5
6.0
8
6.3
6.5
3
6.7
5
6.9
8
7.2
7.4
3
7.6
5
7.8
8
8.1
8.3
3
8.5
5
m
sig
nal
am
pli
tud
e
in line with notch 90 deg to notch
Pipe end
Notch
Initial pulse
Practical Implementation
Energy Focused in-line with Defect
Energy Focused 180° from Defect
Focal Response with constant area
Defect
Shape with
constant
area loss
Axi
Symmetric
response
showing
amplitude
Focus
response
showing
angular
distribution
0
45
90
135
180
225
270
315
0
45
90
135
180
225
270
315
0
45
90
135
180
225
270
315
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
Deep
5% Area
Medium Depth
5% Area
Shallow
5% Area
Focal Response – Constant Angle
Defect
Shape with
constant
area loss
Axi
Symmetric
response
showing
amplitude
Focus
response
showing
angular
distribution
0
45
90
135
180
225
270
315
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
0
45
90
135
180
225
270
315
0
45
90
135
180
225
270
315
Deep
10% Area
Shallow
2% Area
Medium Depth
5% Area
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25 30
Improved Focusing
Sound energy concentrated in one region
Rotation 8 times around pipe
4 times greater sensitivity than cross sectional volume
Multi defect focus capability
Defect / Feature discrimination
Circumferential information is obtained.
Data can be displayed in a more easily interpreted manner.
The operator needs to distinguish between:
• Areas of concern that need immediate attention
• Areas to earmark for inspection in the future
• Areas of no significant problems
This method provides semi-quantitative results
It is an efficient classifier of defects
Enhanced high resolution plots
Classification Scheme
Combine axisymmetric amplitude with distribution of the angular response from focusing, to get a follow-up priority
Defect Category C, where• Amplitude is less than -18dB from weld signal, C = 1
• Amplitude is between -18dB and -12dB from weld , C = 2
• Amplitude is greater than -12dB from weld, C = 3
Directionality Distribution D, where• Angular distribution is less than 45°, D = 3
• Angular distribution is between 45° and 90°, D = 2
• Angular distribution is between 90° and 315°, D = 1
• Angular distribution is 360°, D = 0
A-scan Threshold Levels
Noise
-14dB
Girth welds
100% Reflector
Flange
-20dB
-26dB
-32dB
A-Scan Threshold Levels
Category 1
Category 2
Category 3
Directionality Category 3 Defect
Directionality Category 2
Directionality Category 1
Directionality Category 0
Evaluation Matrix
Product of C and D gives Follow up priority
Low priority Moderate priority High priority
If C x D = 0, the response is a weld
Follow up
priority
Defect Category, C
1 2 3
Directionalit
y
Distribution
, D
0 0 0 0
1 1 2 3
2 2 4 6
3 3 6 9
Usefulness of Focusing
Information about the circumferential extents
GWT- Cased vs. Buried
CUI (Corrosion Under Insulation)
GWT indications confirmed with AUT
Underground Test
Results of Underground Test Loop
Bridge Crossing
Results of Bridge Crossing Test
Certification
TWI Certification Ltd issued the Examination and Syllabus for the
Certification of Personnel Engaged in Guided Wave Ultrasonic Inspection for
the Detection of Corrosion in Pipe – outlined in the LRU Written Practice ISS
2.2 rev 0 Dated May 2007.
• The certifying scheme is the CSWIP-ES-12-04 1st Edition Feb 2004 (Requirements for
Employer Specific Certification of Personnel Engaged in NDT).
• The certification as a minimum complies with ISO 9712 and EN 473.
• Techcorr has eight (8) Level 2 and six (6) Level I Technicians certified under this scheme.
• Most of our Technicians are metallurgical or mechanical engineers whom have gone
through a three (3) year training process internally via our operations in Latin America.
top related