advancements in corrosion inspection techniques
TRANSCRIPT
Advancements in Corrosion Inspection Techniques
4th ICEPIM & OMIC GAS 2018
Page 2
Content
Current corrosion mapping method
Different tools
Results
On-going developments
Future perspective
Oil & Gas – Power GenerationHeat Exchanger Tube Corrosion
Concern
Solution
Fast Inspection Data recordable
corrosion/erosion crack, baffle cuts, small wall loss occur due to prolonged
usage.
MS 5800
Page 4
Oil & Gas – Power GenerationPipeline Corrosion Assessment
Concern
Solution
High productivity inspection with long-range coverage and rapid screening.
Cost reduction for excavation, scaffolding, and insulation removal.
Time consuming using Ultrasonic Inspection
Buried or insulated pipes complete excavation of the pipelines.
Long vertical pipes requires scaffolding for the operator.
UltraWave LRT
Page 5
Oil & Gas – Power GenerationThickness Measurement Spot Check
Concern
Solution
Measurement from one side Easy to use Immediate reading Data Logging IP65
Structural metals subject to corrosion Measure wall thickness to assure
structure integrity
38DLP
Page 6
Oil & Gas – Power GenerationCorrosion Mapping
Concern
Solution
Fast and large coverage with one scan No need to go around the pipe Data archiving for monitoring over time
Internal corrosion Conventional techniques are time-
consuming Limited access around large pipe
38DLP
RexoForm
OmniScan with HydroFORM
Page 7
Current corrosion mapping method
Ultrasonic thickness gauges are extensively used forcorrosion mapping for decades
Corrosion assessment consist of different steps:– Draw grids on the components (typically 25 mm
x 25 mm)– Scan each grid to find the minimum thickness– Feed this data in a software to allow engineering
calculations
Current corrosion mapping issues
This method has the following issues :
–It is slow–It is operator dependant–Grids are large (typically 1 in2)–Small pits can be missed–Too much manipulation of data–Difficult to monitor degradation over time
UT - Different inspection techniques
Low Density
UTG – UT Thickness gaging Surface divided into zones Long process to find the thinnest point Not reliable Operator dependant, no permanent recording Limited use of the data for mechanical engineers Unconsistent POD
Low Density High Density
AUT – UT Motorized Higher points density (strips) Reproducible, if good couplant Low productivity Limited coverage, between strips Fast mechanical movements :
Concern of security for operators Prone to scanner failures Coupling becomes difficult at high speed,
unreadable data points
UT - Different inspection techniques
Phased Array Scanning
4 element aperture 1 mm (0.039 in.)
Phased array probes are composed of multiple piezoelectric elements.
Pulsing and receiving of the elements is electronically controlled to generate beams.
Corrosion inspection is performed using linear scan beams
Large Effective Beam
60 mm (2.36 in.)
4.7 mm (.187 in.)
Conventional pitch-catch Phased array 64 elements
Low Density High Density
PA – Phased Array Slow mechanical movements Improved safety & scanner reliability Higher productivity High points density Volumetric representation Data archiving Usable offline data by non-NDT
engineers and monitoring purposes Compatibility with any mechanical
properties and stress analysis tools
UT - Different inspection techniques
Acquisition units
The OmniScan is the market reference for phased array corrosion inspection– 2 axis encoders for raster scans – Simple setups and calibration through wizards– Full high-resolution A-scan storage.
MX2– Modular for changing needs– Drivable with TomoView for bigger file
size (up to 2GB data file)– Bigger Screen
SX– All the features needed for most
corrosion inspection applications– More affordable– Smaller and lighter for more portability
Corrosion mapping views for analysis
ThicknesssC-scan
A-scan
D-scan
B-scan
Thickness Data Views
Thickness Data Views
C-scan
B-scan
D-scan
Corrosion :
Page 18
Main Components of the PA Corrosion Solution
Acquisition instrument
Probe assembly
Scanner
A large choice of ultrasonic phased-array tools
RollerForm, Rexoform, Dual Linear Array
Manual phased-array tools
HydroFORM
Pulse-Echo using local immersion (ex: HydroFORM)
Tool-less probe positioning fits the following:- Convex surface from 4 in. OD up to flat- Concave surface from 10 in. ID up to flat
NO hard wedges
Gasket and water path design:- Optimum coupling on rough surfaces- Excellent near-surface resolution- No wedge reflection - Easy gate synchronization with the front wall- Low water consumption- Removable lower plate for quick gasket swap
Large footprint:- Increased productivity- Limited in small access areas
Dual Linear Array Probe for Corrosion
Pitch-Catch using hard wedge (ex: Dual Linear Array-DLA)
The Dual Linear Array probe is the ideal complement to the HydroFORM. It offers many advantages over conventional ultrasonic dual element transducers.
Pitch-catch technique produces very little interface echo for improved near surface resolution: 1 mm (0.04 in.)
Quick adjustment system adapts to diameters from 4 in. OD to flat
Beam coverage width up to 32 mm (1.26 in.)
Easy setup with no water management system and preconfigured setup files
1 mm deep pointed pit in qualification plate
Pitch-Catch using hard wedge (ex: Dual Linear Array-DLA)
Dual Linear Array (DLA) Probe – Replaceable Wedge
Dual Linear Array (DLA) Probe – Replaceable Wedge
DLA Probe with Replaceable Wedge
Increased reliability of the probe
Better sound transmission with contoured
wedge and integrated irrigation
Can now be used for motorized inspection
High temp version up to 150 deg C
Beam Coverage of 32 mm
Quick OD adjustment : 4 in. to flat
Carbides wear sliders : smooth movement
Inspection depth from 1 to 80 mm in CS
Quick load setup configuration
RexoFORM
RexoFORM - Hard Wedge Delay Line for Corrosion
38 mm (1.5 in) or 60 mm (2.36 in.) coverage, OD from 4 in. to flat
Near surface resolution of 2 mm (.0690 in.)
Fits standard A12 and A14 probes
No constant water supply needed
Water wheel probe for corrosion
50 mm (2 in.) coverage
0.8 mm (0.03) resolution
Scan speed of 100 mm/s (4 in./s)
Near surface resolution of 3 mm (.0690 in.)
Easy to implement and operate
Rollerform
Typical results obtained Using PA
Cscan Thickness
BscanProfile
Erosion Pittings
Phased Array Calibration and Performance
Calibration and performance demonstration on Flat bottom holes
SCANNERS
Page 34
GLIDER
ChainSCANNER
MapSCANNER
Semi-automated corrosion mapping for pipes
Manually driven
2 encoders
Manual indexing
Compatible with
Hydroform, DLA etc
For pipes from 4in
to 38in OD.
ChainScanner
MapScanner
Up to 300 mm scan width
Common Specifics
Up to 580 mm
scan width
Adjustable index
More stable
HydroFORM Corrosion Mapping System
Fully motorized phased-array corrosion mapping for pipelines
The most productive solution
Up to 600 mm (27 in.) scan width
Each pass covers around 50 mm (2 in)
Resolution 1 mm (0.04 in)
MapRover
Video MapROVER
Remaining Strenght of pipeline calculation
Cscan export (.csv)
Spreadsheet (Excel)
3rd party software
Compatible with codes requirements
– ASME B31G– DNV– etc
Export C-Scan easy function
Right-Click in the C-Scan and select “Export”
Header informations and data
Allow statistical analysis using Excel functions
Export C-Scan easy function
Conditional Formatting – Using Excel
Offline Analysis – Using Excel
External Software Compatibility – Example Creaform
Customizable Report
Tofd for Weld Root Corrosion/Erosion
Used to detect and measure material loss
Very rapid compared to other techniques
Does not require cap removal
Types– Root Erosion/Corrosion– Preferential Weld Corrosion– Flow Accelerated Erosion– Etc.
Conventional Tofd Approach Focus at root (75-90% T ) common
Allow multiple probe positions or offsets
Centered, offset right, offset left
Thinnest measurement found
Excellent for ID cracks
Coming Technology: Flexible PA Probes
Exciting development
Ruggedness and application still being worked on
Potential ability to scan elbows
New development: Flexible PA probe
Probe characteristics: 64 elements
1mm pitch
6mm elevation
5MHz
60% bandwidth
Can cover great range of OD
Small footprint
Can be used directly in contact or with a delay line
With or without encoder
Typical scan plan used on all samples
Results with the flexible phased-array probe only
• One line scan showing erosion on the Cscan.
• The upper Bscan represents portion of the pipe with no erosion
• The lower Bscan represents the position where the erosion is maximal.
• This is a the limit of the dead-zone of the probe
• Some Missing data
Flexible phased-array summary
Advantages– Flexible phased-array can shape complex components– Dead zone of 3-4 mm– Dead zone can be reduced to 2 mm with a delay line– Patient operator can inspect large surfaces
Limitations– Difficult to couple the probe to the part (missing data)– Maintain constant pressure on the probe (repetability)– Encoder difficult to attach (cumbersome to use)
Therefore, an immersion delay line concept was developed
Flexible phased array probe holder description
– Wedge has a fixed diameter
– Probe slides into the wedge
– Wedges for other diameter canbe changed in 30s
– Irrigation and local immersion asin the HydroFORM®
– Water colum of 8 mm
– Sealing assures by foam layer
Flexible phased array probe holder
–Can be used with a Mini-Wheel™encoder or only manual
–Inspectors can draw an equidistantscan line on the surface of the elbow tohelp ensure complete coverage of thepart.
–The user affixes the water wedge tothe tube’s surface and follows thedifferent grid lines
But :–Keeping pressure to keep water in is achallenge, especially for elbowsdifficult to reach
Video Elbow Scanner
Prototype for elbow inspection
Flexible phased-array probe
Local immersion wedge
Scanner
Composed of 3 components
Scanner description
– Diameter ranging from 4 in.nominal pipe size (NPS) to42 in. NPS
– The scanner is designed tohold the water wedge inposition and automaticallyapplies pressure tomaintain coupling betweenthe inspected part and theprobe.
– Two magnetic wheels tosecurely hold it in positionon the pipe
– Local immersion wedgescan be changed quicklywithout tools
Scanner description
– Automatic height adjustments using special spring loaded arms.– At the intrados, the wedge should be below the wheel centerline– At the extrados, the wedge should be slightly higher– The spring loaded system also helps ensure constant pressure on the
wedge to maintain coupling (water column)
scanner at various positions around an elbow
Figure 8 — Elbow sample with flow-accelerated corrosion
Experimental results
Different elbows were examined in laboratory conditions
Scan Parameters and Focal Law Configuration
Probe
Frequency 7.5 MHz
Pitch 1 mm
Elevation 7 mm
Focal Law Aperture 4 elements
Scan Resolution 1 mm × 1 mm
Water Column 8 mm
Results on elbow with Flow Accelerated corrosion
Sample description:– Outside diameter: 203 mm– Nominal thickness: 7mm
Inspection set-up:– Grid of 55 mm were drawn on the
elbow– Acquistion every 1 mm– The entire surface was scanned in 15
passes to allow overlap– Duration of the scan: less than 15
minutes– The same sample was scanned 7
times
Results on elbow with Flow Accelerated corrosion
3-4 pages of results
Elbow fully inspected in less than 10 passes
Inspection time: few minutes
High density of data
No missing point
Results : Elbow with Flow Accelerated Corrosion
Results on elbow with Flow Accelerated corrosion
Every scan line has a different length
Smallest scan line corresponds to the intrados while the longest scan line corresponds to the extrados.
Minimum thickness of 3,05 mm on the extrados
Precision and repeatability are very good
Results on elbow with pittings
Sample description:– Outside diameter: 170
mm– Nominal thickness:
20mm
Inspection set-up:– Grid of 55 mm were
drawn on the elbow– Acquistion every 1 mm– The entire surface was
scanned in 15 passes to allow overlap
– Duration of the scan: less than 15 minutes
Figure 11 — Elbow sample with pitting on the middle line
Results on elbow with pittings
Results on elbow with pittings
Thinner section is located between the intrados and the extrados in one side only
Several corrosion pits mostly found on the tube axis line between the intrados and the extrados.
Minimum thickness found is 12 mm
Results on elbow with erosion and pitting
Zoomed viewed showing corrosion pits on C, B and Ascan
Cscan export function
The OmniScan® software enables the user to easily export the C-scan data into a .csv file
Compatible with a wide variety of third-party software programs.
Advanced or customer-specific features can be used to make detection and analysis easier.
For example, MS Excel can be used to statistically analyze the part thickness profile.
Features such as automatically listing pits position, average thickness, minimum thickness, and proportion of area under a predefined thickness threshold can easily be implemented using third-party software.
Perspectives
The prototype scanner presented is not commercially available yet
Only the flexible phased-array is commercially available
Olympus will pursue on-site testing with our partners to improve and further develop this solution
Benefits of Phased Array for Corrosion
Large effective beam
Fast inspection speed
High-resolution inspection
Data point density (typically every mm2)
A, B, and C-Scan visible simultaneously
Archiving
Reporting
Exported data suited for non-NDT experts
Conclusion
Acquisition units
OmniScan SX : perfect for the corrosion jobs
SX– All the features needed for most
corrosion inspection applications– More affordable– Smaller and lighter for more portability
Conclusion on Corrosion Mapping Solution
Olympus has developed a series of tools to perform high-resolution thickness mapping
A set of tools (manual, semi-automated and motorized) allows to cover different needs for corrosion mapping
Phased array technology enables faster inspection as well as easy data archiving and interpretation
New development tools like flexible phased-array probe and elbow corrosion will permit to address highly challenging corrosion mapping of complex shapes
Thank you!