U31D UNDERWATER ACFM CRACK MICROGAUGE
from TSC Inspection Systems

The Model U31D Underwater ACFM Crack Microgauge represents a significant advance in ACFM subsea inspection technology. The new instrument has all the advantages of ACFM inspection available on other TSC instruments, but in a much smaller, lighter package designed specifically for diver deployment.

The system provides:

•  Rapid scanning using a hand-held probe.
•  Reliable crack detection and sizing (length and depth).
•  Reduced cleaning requirements with no need to clean to bare metal.
•  Capable of inspecting corroded surfaces through non-conducting coatings several mm thick.
•  Windows software for ease of operation and compatibility with other Windows applications.
•  Full data storage for back-up, off-line view and audit purposes.
•  Access to a wide range of geometries using TSC's new range of active subsea probes.
•  Probes with embedded serial numbers to simplify operation & reduce chance of operator error.
•  Capable of operating at water depths up to 300m.

Background to ACFM

Alternating Current Field Measurement (ACFM) is an electromagnetic Inspection technique and relies on the fact that an alternating current flowing in a component will be disturbed by the presence of a crack. The ACFM probe introduces an electric current locally into the structure and measures the associated electromagnetic fields close to the surface. The presence of a defect disturbs the associated fields and the information is graphically presented to the system operator. The ends of a defect are easily identified to provide information on defect location and length. The significance of a defect, in terms of structural integrity, generally depends on the depth of the defect. Using mathematical models, the stem also provides the depth of the defect, thus allowing an immediate evaluation of the significance of the indication.

This is a major advantage compared to other techniques that only give detection or at best, length information. ACFM systems have been used for a range of applications where rugged inspection systems are needed. The speed of scan provides a rapid and cost effective means of inspecting welded connections with reduced cleaning requirements compared to conventional techniques.

The probes have been developed to minimize signals from features that are not cracks, e.g. corrosion, undercut, HAZ, material property changes, etc, thus overcoming the problems often associated with other electromagnetic systems and minimizing false calls.

The ACFM technique has been approved for weld inspection by major authorities around the world, including Lloyds, ABS, Bureau Veritas, DNV and OCB Germanischer Lloyd.


Background to TSC Inspection Systems

Established in 1984, TSC are leaders in the application of ac field measurement techniques to industrial applications. The ACFM technology has been developed in-house from the successful ACPD technique to provide a system for crack detection and sizing without the need for any electrical contact. The crack sizing capability has resulted from theoretical studies at the Wolfson NDE Centre at University College London, which allows the prediction of crack depth from a knowledge of the surrounding ac electromagnetic fields. The hardware developments make use of state of the art low noise analogue electronics and the control system has been developed using the very latest Windows software techniques. The result is a system that provides reliable subsea inspection of welded structures that has been developed by a Company specializing in structural inspection and structural integrity assessment. TSC are therefore in a unique position and able to provide customers with not only the inspection system, but also the back-up in terms of procedural development, customization to suit spec applications and even an evaluation of the significance of any defects found. 

System Specification

Subsea Unit Weight:  7.6kg in air- 4.3kg in water
Subsea Unit Size:  142mm diameter x 260mm
Probe Cable Length:  5 meters standard, up to 50m by special request.
Serial Communications Cable:  5 m as standard up to 30m if required.
Operating Temperature:    -20° + 40°C
Maximum Operating Depth:   300m as standard, can be extended to 2000m for ROV deployment (See Product Information for U31 R)
Power Requirements:   110v AC. 200mA
Optional Array Support:   16 channels (i.e. 8 sensor pairs) plus position encoder

Software

The U31D operates with TSC's QFM suite of software thus providing a common operating environment with other ACFM products. This avoids the need for operator retraining.

The QFM Software contains the following features
• Operates in Windows 95, 98 or NT environment. Supporting simultaneous running of word processor/spreadsheet package etc, and interface to all common printers.
•  Graphics display of processed data for crack detection.
•  Automated clock markings to indicate position on scan.
•  Variable speed time base to suit application.
•  Multiple screen facility for comparing consecutive scans.
•  Screen marker to identify special features.
•  Replay facility to review data.
•  Real time adjustment of trace position on screen.
•  Moveable cursors for use during data review.
•  ACFM crack depth calculation and crack size data shown on screen.
•  Free format text input associated with each file.
•  Multiple page facility in a single file.
•  Automated back up of data onto diskette and hard disk.
•  Full system status reports for checking hardware.
•  Graphical print out of data screens.
•  Data transfer into standard spreadsheets.
•  Automated set-up of probe-dependent instrument settings.
•  Allows off-line review and analysis of data as originally collected.
•  Crack depth sizing over a wide range of coating thickness'.
•  Operating procedures and software user manuals are available in on-line Windows help files.


Comparison with U21 Underwater ACFM Crack Microgauge
The Model U21 Crack Microgauge is in use around the world for subsea weld inspection.

The Model U31D provides all the functionality of the Model U21 but in a much smaller package. 


Quick Comparison:
Subsea Unit                                         U31D                                 U21
Size (excluding fittings)              142mm dia x 260mm          270mm dia x 510mm
Weight in Air                                         7.6 Kg                                33 Kg
Weight in Water                                     4.3 Kg                               4.0 Kg
Maximum Operating Depth                       300m                                300m
Maximum Probe Cable Length                  50m                                   5m

Topside Unit
Size                                             240 x 200 x 110mm             560 x 350 x 180mm
Weight                                                    2Kg                                     9Kg

 Size difference between U31 and U21 Subsea Units

Operator Training
Lloyds JCSWIP Accredited Operator training courses are held at various centers In the United Kingdom and overseas, details on request. The course duration is five working days.  In Europe and the U.K. contact The Welding Institute.

In the United States contact Hellier Associates, Houston TX

Availability
The U31 Underwater ACFM Crack Microgauge is available from TSC worldwide through our network of agents and distributors.

Details of these can be found on the TSC website, or contact TSC direct for further details.

Inquiries
Sales and Technical Inquiries:

                        TSC Inspection Systems
                        6 Mill Square, Featherstone Road
                        Wolverton Mill, Milton Keynes MK12 5RB
                        UNITED KINGDOM
                        Tel No:  + 44 (0)1908 220255
                        Fax No: + 44 (0)1908 220959
                        Email:   sales@tscinspectionsystems.com
                        Web:    www.tscinspectionsystems.com

® ACFM is a registered trade mark of Technical Software Consultants Limited

Please Note:  As part of its continuing program of product improvement, TSC reserves the right to alter specification without prior notice.

October 22, 2007

Back to Amigo

info@ndtint.com