ACFM CRACK MICROGAUGE MODEL U9
The ACFM Crack Microgauge Model U9b represents a significant advance in inspection technology and provides the capability of both ac potential drop (ACPD) and ac field measurement (ACFM) techniques. The alternating current field measurement technique enables reliable crack detection and crack depth measurement on a wide range of components and structural geometries. Advanced software aids the operator in the interpretation of the inspection data to provide reliable crack detection with low likelihood of false calls. Crack depth predictions are based on mathematical modelling and the system therefore requires no calibration procedure, significantly reducing the possibility of operator error.
TSC offer full support from our engineers experienced in weld and fabrication inspection worldwide. The system has been used by major operators since 1992.
The system provides:
- Rapid scanning using a hand-held probe
- Reliable crack detection and crack sizing without need for calibration, i.e. Crack LENGTH and Crack DEPTH
- Multi frequency option - 200 Hz, 1 kHz, 5 kHz
- Ruggedised site units capable of running under battery or mains power
- Reduced cleaning requirements with no need to clean to bare metal
- Capability of inspection through metallic and non-metallic coatings
- State-of the-art Windows software for ease of operation
- "Replay" facility for review of data
- Fully automated back-up facilities for data storage
- Suitable for use with abseiling techniques using long probe cables
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Access to a wide range of geometries using TSC’s range of topside probes
BACKGROUND TO ACFMAlternating 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 system 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 minimise signals from features that are not cracks, eg corrosion, undercut, HAZ, material property changes, etc, thus overcoming the problems often associated with other electromagnetic systems and minimising 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.ACPDThe system also supports the ACPD technique, available as an option on the instrument, which provides detailed crack profile measurement without any requirement for calibration or operator interpretation. The crack depth information, at any point on a crack, is obtained by making two measurements with the hand-held probe from which the instrument calculates crack depth and displays this directly in millimetres.Using the ACPD system provides:
- Crack depth measurement on a wide range of metallic components
- No operator interpretation
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Detailed information on crack shape
SYSTEM SPECIFICATION
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Unit Weight (Battery Powered)
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5 kg
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Optional Mains Pack - 110/240 V
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3 kg
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Analog output
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Optional
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Probe cable lengths
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Up to 20 metres
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Serial communications cable length
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Up to 25 metres
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Operating temperature
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0 - 35 °C
SYSTEM FEATURESHardware- Rugged Topside Unit for battery or mains operation
- Earth Leakage Trip protection for complete system
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Range of ACFM probe configurations to cover different geometries:
- Standard Probe for general weld inspection.
- Tight Access Probe for angles tighter than 35°.
- Pencil Probes for difficult access or grinds.
- Edge Effect Probes to allow inspection up to plate edge.
- Miniature and Micro Pencil Probe’s with side and straight entry cables. Used to inspect items for small defects in difficult access areas such as rat holes and gusset plates.
- Drill Pipe Thread Inspection Probes to examine threaded PIN and BOX components.
- Universal Thread Inspection Probe. Uses interchangeable shoes.
SOFTWAREThe QFM Software contains the following features- Operates in Windows 3.1 or Windows 95 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 available in on-line Windows help files.
