ACFM OVERVIEW - tcontrol.ro

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ACFM® – OVERVIEW

Agenda

1. Introduction to ACFM

2. ACFM working principles

3. Tools and applications

4. Subsea specific tools and applications

5. Training

6. Conclusion

Introduction

Introduction to ACFM

• Works on ferrous and austenitic materials

although:

• More applications are found with ferrous steels

• Sizing is slightly more accurate sizing in ferrous

materials

• Depth sizing of deep cracks:

• Sizing flaws up to 25mm deep (Weld probe)

• Ideal for large, rough structural welds

• The technique of choice for fatigue crack assessment

• Inspection through thick coatings:

• Sizing possible with up to 4mm thick coatings,

• Detection possible with up to 10mm of LO with reduced

sensitivity

WHAT IS ACFM USED FOR?

‟Detect and size surface breaking cracks in metallic structures through coating”


• Efficient and cost effective:

• Minimal surface preparation

• Fast scans / wide coverage / rugged / forgiving

• Versatile

• User-friendly

• Sizing capability = cost effective remedies

• Pedigree / credibility:

• Field proven reliability and high POD

• Approved by regulatory bodies

• Highly compatible, portable and auditable data records

• Comprehensive inspection planning and reporting

WHY ACFM


INDUSTRIES AND APPLICATIONS

And more…

ACFM Origins

• Existing NDT left much to wish for…

• MPI:

• Requires extensive cleaning / coating removal

• No depth sizing / no remaining life assessment

• Not ROV deployable

• ECT:

• Poorly marinized (Back in the days)

• Too sensitive for underwater deployment

• Depth sizing unreliable and limited to about 5mm

• ACPD, a completely forgotten technique today but

back then:

• Was good at sizing BUT required bare metal

• Was difficult to apply underwater

1980’S: FATIGUE CRACKING ISSUES IN SUBSEA O&G STRUCTURES

ACFM Origins

• University College of London:

• Original technological development

• First instruments/probes designed and built

• Development of a mathematical model for sizing

• Substantial investments in validation:

• Funded by JIP – Shell, BP, CP, BG

• UW blind trials to compare ACFM, MPI and EC

• Full POD using several realistic defects and geometries

• POS data (Below) still used for normalizing ACFM sizing

• Led to extensive ICON trials offshore

EARLY 1990’S: DEVELOPMENT OF THE ACFM SOLUTIONElectric Field

Magnetic Field

0

5

10

15

20

25

0 5 10 15 20 25

AC

FM

Pre

dic

ted

de

pth

, m

m

Characterised depth, mm

Depth from ACPD/TOFDbefore coating

Depth from ACPD/TOFD - nocoating

Depth measured aftersectioning

Equality

+15%

-15%

ACFM working principles

Key Elements

Uniform

FieldsButterfly Sizing


• The field coil:

• Sits high in the probe (Blue)

• Is driven with a constant alternating current source

• Generates a uniform field in the target

• Cracks disturb the flow of fields in the target:

• Some are forced under it (Green)

• Some flow around its edges (Red)

• Small coils in closer proximity to the target senses the

disturbances:

• The Bx coil (Green) is sensitive to fields diving under the crack

• The Bz coil (Red) is sensitive to fields flowing around the crack edges

UNIFORM FIELDS


• The Bx signal:

• Generally goes down when going over a crack

• Amplitude is related to the crack depth

• Is used to discriminate between crack orientations

• The Bz signal:

• Generates a trough near one crack end and a peak near the other end

• Is related to the crack length

• The butterfly:

• Is a combination of the Bx and Bz signals

• Provides simple and clear information

• Enables efficient and reliably analysis with easy to learn rules

• Can be used to discriminate between cracks and other features

BUTTERFLY

• No onsite calibration: the sizing capabilities are self

contained in the system

• Assisted analysis:

• Automatic gating captures the essential parameters

of the signals

• The parameters are processed by software

• Defect sizing is based on a mathematical model of

the electromagnetic field – crack interaction

• Comprehensive reporting:

• Automatically generated reports

• Includes signal / C-scan screenshots

• Includes detailed flaw position and measurements

• Provides fully auditable and transparent inspection

records

• General detection and sizing figures:

SIZING AND

REPORTING

ACFM working

principles

• Hi field coil, uniform fields and constant current means:

• Less probe induced variables

• Disturbances largely dominated by cracks, much less by LO

variations or weld roughness

• Wide coverage makes it forgiving to inspectors

• … In short: Improved POD and reduced false calls

• The combination of sensor coils provide rich and clear

information:

• Enables further discrimination of flaws vs noise

• Enables accurate length and depth sizing

• Unique sizing capabilities:

• Sizing flaws up to 25mm deep (Weld probe)

• Sizing possible with up to 4mm thick coatings,

• Detection possible with up to 10mm of LO with reduced

sensitivity

WHAT MAKES IT SO

SPECIAL

ACFM working

principles

Tools and applications

ACFM approvals

Recommends the control of welds using the

Alternating Current Field Measurement technique

or A.C.F.M.

Standard Practice for Examination of Welds using

the ACFM Technique (E2261-03), latest revision

E2261-12

Standard Practice for Examination of Drill String

Threads using the ACFM Technique (E2928-13)

ASME V Article 15: ACFM Technique, 2006

ACFM instruments

Amigo™ 2

Pace®

• Powerful, fast

• High quality multichannel data

• Supports multiple applications

• High probe compatibility: legacy,

Sensu, Sensu 2, high speed

arrays and application specific

• Modern, state of the art

hardware/software

• Ideal for rope access

• Basic weld inspection

• Supports 5/50KHz Sensu pencil

probes:

• Straight

• Right angle

• Transverse

GENERIC SENSU 2

PROBES

TOOLS

• All Sensu 2 probes feature:

• IP65 rating

• Fast acquisition, pristine data quality, high SNR

• Connectorized to 5, 20 or 50m cables

• Config/calibration stored in probe memory

• Convenient buttons and LED indicators

• The new Sensu 2 flagship probes: high speed arrays

• Integrated encoder and coverage up to 90mm

• Dual fields: Bi-axial crack detection and sizing in one pass

• Spring loaded micro-elements. Typical crack detection is

5mm x 0.5mm and above, crack depth sizing up to 20mm

• Weld probe:

• Features stabilizers and a wider field

• The wider field enables depth sizing as deep as 25mm

• Covers 15mm in one pass

• Pencil probes:

• Versatile and ideal for tight access

• 3 orientations available


SOFTWARE

PACKAGES

TOOLS

Pace Amigo 2

Embedded software for portable units✓ Acquisition

✓ Analysis

✓ Report generation and export (Word, PDF, Excel)

Included in Pace unit

ASSIST-GO-SS1

ASSIST-GO-SS5

Reader/viewer for desktopSame interface and functionalities as GO

✓ Data readback

✓ Analysis


Not supported for PaceASSIST-CP-SS1

ASSIST-CP-SS5

Acquisition and analysis software for

desktop ✓ Acquisition / remote control capabilities (RDAU)

✓ Inspection planning, analysis and reporting functionalities


Not supported for Pace

ASSIST-PRO-SS1

ASSIST-PRO-SS5*ASSIST-PRO-DIVER also compatible but more

expensive so only relevant if the customer owns U41

ACFM applications

PROCESS PLANT & REFINERY INSPECTION

Crack detection and sizing through coatings on:

• Pipework

• Pressure vessels

• Attachments

• Nozzles

• And much more…

STORAGE TANK

WELD INSPECTION

ACFM

applications

• Crack detection and sizing with

minimal cleaning

• Wide adoption in France

(COFREND)

• Annular welds with weld probe

• Fast array probe scans:

• Generic welds in one pass

• Lap joints up to 10mm high

• High temperature components requiring in-

service inspection:

• Pre- and post-inspection of hot tapped

weldolets and split tees

• Pressure vessels

• Steam pipes, etc.

• Conventional methods (MT/PT) are limited:

• Typical max. temp: 50-60°C

• Specialist variants can go up to 200-215°C but

come with compromised sensitivity

• Standard ACFM probes:

• 80°C in continuous

• Contact time @ 150°C: 50 seconds

• Contact time @ 200°C: 10 seconds

• Special air cooled ACFM probes:

• Performance demonstrated at 300°C

• Lab tested up to 400°C

HIGH TEMPERATURE

COMPONENTS

ACFM

applications

CIVIL STRUCTURES

ACFM

applications

Amusement parks Cranes

Bridges Building frames

ACFM applications

DRILL STRING THREAD INSPECTION

• Drill string threaded connections are critical to drilling

operations:

• Weakest link of the bottom hole assembly (BHA)

• Sustain heavy stresses and are prone to fatigue cracking

• Lost BHA due to thread twist-offs are very expensive

(~400K USD)

• Traditional inspection methods (MT/PT) leave much

to wish for:

• Requires careful cleaning, slow inspection process

• Difficult geometry and bad visibility compromises detection

• Dirty process: Not environmentally friendly

• No crack depth sizing/no cost effective remedy decisions

• ACFM offers a reliable and cost effective alternative!

THE ACFM UNIVERSAL THREAD

PROBE (UTP)

• One probe for pin/box

• 3D printed shoes are used to mate with

various diameters/thread pitch

• Box ID supported:

–From 3.5’’ IF, 3.5’’ Reg., NC38 and up

• Supported thread pitch:

–As small as 4 TPI

–Down to 5 TPI with slight sensitivity loss

• String on rollers for high productivity

• Fast, reliable, field proven

ACFM applications

• When used on drill string threads, MT POD is

not as good as usually expected

• Comparative trials were conducted…

• Halliburton tried over 140 threads:

• ACFM identified 23 defects with depth information

• 9 could be reworked and returned to service

• 2 were missed with MT

• Shell tried over 20 drill collars:

• 2 discrepancies between ACFM and MT were re-

inspected and sectioned…

• MT missed a 0.016’’ deep crack found with ACFM

• MT produced one false call

• Experience has shown that in general, ACFM

finds genuine flaws on 1-2% of threads

previously inspected and missed by MT

• ACFM is approved by NS2 and ASTM

international for this application

PROVEN

SUPERIORITY FOR

DRILL STRING

THREAD INSPECTION

ACFM

applications

X125

X50* POD curve source: Dale B A and Moyer M C. "Sensitivity and Reliability of Commercial Drillstring

Inspection Services". 7th Offshore South East Asia Conference, Singapore, February 1988.

MT missed

MT overcall

ACFM applications

RAILWAY RELATED APPLICATIONS

• ACFM a railway proven inspection technique for ~20 years

• Axle and wheelset inspection:

• Fatigue cracking detection and sizing

• An independent blind trial on 15 failed axles was conducted

• ACFM proved to be superior to ECT and far superior to MT/MPI

• Various welds inspection:

• Tank car welds

• Bogie frame welds

• Attachment welds

• Rail inspection:

• Fast and reliable detection of Rolling Contact Fatigue (RCF) cracks

• ACFM has been tested, field proven and approved by UK railways, Corus Rail Technologies (on behalf of Network Rail), Balfour Beatty Rail Technologies and York EMC Services, UK.

ACFM applications

AXLE INSPECTION DETAILS

• ACFM was proven during an

independent blind trial*:

• 15 axles with known failures

• ACFM has the highest POD and

lowest false calls

• ACFM adds the depth sizing

capability on top of detection

• Perfect match for the Amigo 2 /

Sensu 2 array probes

Experimental

POD

Potential

POD

Axles flagged

as ‘’Failed’’

MT/MPI 44% 59% 5

ECT 80% 85% 11

ACFM 84% 95% 15

* M Pollard and A Lear, ‘Report 11363/03 – Evaluation of Electromagnetic Non-destructive Testing Techniques – Executive Summary and Recommended

Way Forward’, The Engineering Link, 2000.

ACFM topside applications

RAIL INSPECTION DETAILS

• ACFM proven during an independent blind trial:

• Corus Rail Technologies on behalf of Network Rail

• Tested 72 rail sections with RCF cracking, proofed with destructive testing

• “…the capability of detection of the ACFM® system has been found

to be close to 100%.”

• Other successful trials by UK railways, Balfour Beatty Rail Technologies

and York EMC Services, UK.

• Semi-autonomous deployment or “Walking stick”

• Rich data:

• High resolution

• Fast collection: 20Km/h+

• Clear C-scan representations

• ACFM is field proven and ideal for mining

applications:

• Difficult environments, dirty/greasy/worn

components

• Large defects in big components

• Frequent fatigue cracking requiring depth

sizing

• Typical applications:

• Welds in large structural components

• Gear teeth inspection (ACFM specified by

ASTM E2905)

IN THE MINING

INDUSTRY

ACFM

applications

Subsea specific tools and applications

ACFM subsea

APPROVALS

Non-Destructive Testing of Hull Welds, February 2014. Section 6, ACFM Technique

Classification Note No. 7, March 2012. Section 2.1, Detection of surface breaking cracks

Accepted for in-service examination of structural welds

TSC is also an LR certified ACFM Inspection Services Provider

BS EN ISO 19902: Petroleum and natural gas industries. Fixed steel offshore structures

Approved technique surface breaking crack detection

U41: for the deep

• Ideal for diver inspection down to 300m

• Connects with up 3x Sensu 2 UW probes simultaneously,

avoiding frequent returns to the surface

• Connects to the topside unit with up to 3x 150m umbilical

• State-of-the-art electronics: fast scans, high data quality

• Array probe support:

• Diver mini-array probe with 36mm wide coverage

• ROV full-array probes

• Reduced number of scans

• Faster recognition and characterization of defects

• For deeper ROV applications: See TSC Subsea

Amigo™ 2: for shallower waters

• Topside deployment through 50m underwater

cables

• Versatile: also supports multiple topside

applications

• State-of-the-art electronics: fast scans, high

data quality

• Supports the same probe heads as the U41

but connected through 50m cables instead

SOFTWARE

PACKAGES

ACFM UNDER

WATER

U41

Analysis software for desktop ✓ Acquisition / remote control capabilities (RDAU)

✓ Advanced analysis and reporting functionalities


ASSIST-PRO-DIVER-SS1

ASSIST-PRO-DIVER-SS5

GENERIC SENSU 2

UNDERWATER

PROBES

SUBSEA

TOOLS

• All Sensu 2 underwater probes feature:

• IP68 rating down to 300m underwater

• Fast acquisition, pristine data quality, high SNR

• Cable options: 5m for U41, 50m for Amigo 2

• Config/calibration stored in probe memory

• Diver mini-array:

• Designed to make divers’ work easier and more reliable

• Features stabilizers and a 36mm wide coverage

• Weld probe:

• Features stabilizers and a wider field

• The wider field enables depth sizing as deep as 25mm


• Tight access probe:

• A weld probe designed for hard-to-reach areas

• Ground weld probe:

• Features a long slender nose to fit into weld repair grinds

• Enables monitoring throughout the repair process

• Pencil probes:

• Versatile and ideal for tight access

• 3 orientations available all with 15mm wide coverage

ACFM UNDERWATER

COMMON

APPLICATIONS

• Jackets:• Structural node welds

• Attachment welds: looking for cracks

when there is a flooded member

• Jack-ups:• Leg node welds

• Spudcan welds

• Hull inspection

• Semi-subs:• Leg welds

• Hull welds (UWILD inspections)

• FPSOs: hull inspections

• Pipeline damage investigation (anchor,

drag, etc.)

• Mooring systems including chains

ACFM Training

• Eddyfi Academy

• Online product training

• SNT-TC-1A compliant ACFM level 2 by blended learning

• Operator Certification available through SNT-TC-

1A, PCN, and CSWIP Schemes

• PCN through Lavenders International (UK,

Houston, and others)

• CSWIP through TWI (UK and others)

In Conclusion

• ACFM is a mature and certified technique

• Crack detection + length and depth sizing

• Cleaning not required

• Works on ferromagnetic and austenitic

• Auditable: all data is stored

• Rugged, forgiving and perfect for robotic integration

Documents

ACFM OVERVIEW - tcontrol.ro