advancements in corrosion inspection techniques

Advancements in Corrosion Inspection Techniques

4th ICEPIM & OMIC GAS 2018

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

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

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

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

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


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


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 :

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

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

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


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


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


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!

advancements in corrosion inspection techniques

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