- Email: [email protected]
Focussed probe detects near-surface defects
Focussed probe detects near-surface defects A high frequency focussed ultrasonic transducer for detection of small, near-surface defects is available from All Inspection NDT for immersion testing applications.
PVdF ultrasonic immersion transducers claimed to improve near-surface resolution Piezoelectric polymer ultrasonic transducers for immersion testing have been developed by Fulmer Research Institute (NDT International, October 1984, p 286) and are available from Wells Krautkramer. The piezoelectric polymer PVdF is claimed to have a very broadband frequency response. It is highly damped and so can produce singlecycle pulses giving improved nearsurface resolution for defect evaluation and thickness gauging. The polymer is acoustically well matched with water for immersion applications. PVdF is more attractive than conventional piezoelectric, says Nigel Gray of Fulmer, from a transducer manufacturing point-ofview. The polymer is more easily
Subsea corrosion monitor f i t s ROVs Subsea ultrasonic corrosion monitoring at depths of 1000 m is possible with Rovprobe 1000, which is designed to be conveyed to the inspection site by a remote operated vehicle (ROV). The transducer is connected to an electronic processor housed in the nOV and signals are then transmitted to a surface display unit via the ROY umbilical. Display is o n a LED, o r a n A - s c a n
fabricated than delicate piezoelectric crystals, and since individual PVdF elements can be cut from a single sheet the thickness of the active transducer element is highly reproducible. The principal difficulty with the material, which Fulmer says it has now overcome, is that PVdF is inert -- electrical connections are difficult to make and maintain, especially at transducer excitation voltages typically up to 1000 V. Eight standard probes are available with nominal centre frequencies between 1 MHz and 25 MHz, with diameters up to 25 mm. Probes with special frequencies down to 0.1 MHz can be made to order.
Wells-Krautkramer, Blackhorse Road, Letchworth, Herts SG6 I HGF, UK
All Inspection NDT Ltd, 59 Lynchford Road, Farnborough, Hampshire GU14 6EJ, UK
Fluorescent magnetic ink A fluorescent magnetic ink has been introduced by Magnaflux, The ink, WB-1, consists of a liquid concentrate of iron oxide bonded with a fluorescent pigment mixed into a concentrate of non-ionic surfactants and corrosion inhibitors. It is supplied in 2 5 0 ml containers which make 25 I of full strength ink when added to water.
Magnaflux Ltd, South Dorcan Industrial Estate, Swindon, Wiltshire SN3 5HE, UK
gain system. Automatic mode can be overridden by manual mode if necessary.
Eddy-current unit fitted with digital module
The stainless-steel transducer measures 32 mm diameter by 45 mm. The subsea electronic unit is 185 x 125 x 5 5 m m a n d i s powered from a DC supply between 18 and 30 V, compatible with most ROVs.
A high definition digital storage and display module is fitted to the EIotest B2 SDM, the latest in the range of eddy-current crack detectors from Rohmann.
Baugh Et Weedon Ltd, Widemarsh Street, Hereford HR4 8EZ, UK
on an
oscilloscope. Introduced by Baugh and Weedon, the probe is based on the company's Seaprobe. Measurement range of the standard system is 10 to 50 mm with a resolution of O.1 mm. Material calibration is up to 10 m s -1 in steps of 1 m s -1. In general, the system operates automatic signal selection which is protected by an automatic gain control with a range of at least 40 dB and a user accessible swept
Using a focussed, heavily damped (single cycle pulse) 50 MHz crystal, the transducer has a centre frequency of approximately 40 MHz, the overall range extending from 32 MHz up to 48 MHz. When used in conjunction with a high frequency pulser/amplifier, the transducer is capable of resolving 2 0 0 /zm defects in ceramics, says the c o m p a n y - focal spot has been measured as 2 5 0 /~m.
On a digital unit the trace display is built up from a series of dots. This eddy-current unit has capacity for 8 0 0 dots, spread over two 64k RAM. An automatic 'roll' facility erases dots which have been displayed. A 'speed" control adjusts the rate at which dots are displayed, enabling a high definition trace to be produced. Conventional analogue mode is also available. Operation can be in static mode, or for automatic testing with rotating probes, in dynamic mode.
Underwater thickness gauge from Baugh Et Weedon attaches to remote operated vehicles
NDT INTERNATIONAL. OCTOBER 1985
Rohmann (UK) Ltd, Unit 8, Bumpers Farm Industrial Estate, Chippenham, Wiltshire SN14 6 LH , UK
307
PVdF ultrasonic immersion transducers claimed to improve near-surface resolution Piezoelectric polymer ultrasonic transducers for immersion testing have been developed by Fulmer Research Institute (NDT International, October 1984, p 286) and are available from Wells Krautkramer. The piezoelectric polymer PVdF is claimed to have a very broadband frequency response. It is highly damped and so can produce singlecycle pulses giving improved nearsurface resolution for defect evaluation and thickness gauging. The polymer is acoustically well matched with water for immersion applications. PVdF is more attractive than conventional piezoelectric, says Nigel Gray of Fulmer, from a transducer manufacturing point-ofview. The polymer is more easily
Subsea corrosion monitor f i t s ROVs Subsea ultrasonic corrosion monitoring at depths of 1000 m is possible with Rovprobe 1000, which is designed to be conveyed to the inspection site by a remote operated vehicle (ROV). The transducer is connected to an electronic processor housed in the nOV and signals are then transmitted to a surface display unit via the ROY umbilical. Display is o n a LED, o r a n A - s c a n
fabricated than delicate piezoelectric crystals, and since individual PVdF elements can be cut from a single sheet the thickness of the active transducer element is highly reproducible. The principal difficulty with the material, which Fulmer says it has now overcome, is that PVdF is inert -- electrical connections are difficult to make and maintain, especially at transducer excitation voltages typically up to 1000 V. Eight standard probes are available with nominal centre frequencies between 1 MHz and 25 MHz, with diameters up to 25 mm. Probes with special frequencies down to 0.1 MHz can be made to order.
Wells-Krautkramer, Blackhorse Road, Letchworth, Herts SG6 I HGF, UK
All Inspection NDT Ltd, 59 Lynchford Road, Farnborough, Hampshire GU14 6EJ, UK
Fluorescent magnetic ink A fluorescent magnetic ink has been introduced by Magnaflux, The ink, WB-1, consists of a liquid concentrate of iron oxide bonded with a fluorescent pigment mixed into a concentrate of non-ionic surfactants and corrosion inhibitors. It is supplied in 2 5 0 ml containers which make 25 I of full strength ink when added to water.
Magnaflux Ltd, South Dorcan Industrial Estate, Swindon, Wiltshire SN3 5HE, UK
gain system. Automatic mode can be overridden by manual mode if necessary.
Eddy-current unit fitted with digital module
The stainless-steel transducer measures 32 mm diameter by 45 mm. The subsea electronic unit is 185 x 125 x 5 5 m m a n d i s powered from a DC supply between 18 and 30 V, compatible with most ROVs.
A high definition digital storage and display module is fitted to the EIotest B2 SDM, the latest in the range of eddy-current crack detectors from Rohmann.
Baugh Et Weedon Ltd, Widemarsh Street, Hereford HR4 8EZ, UK
on an
oscilloscope. Introduced by Baugh and Weedon, the probe is based on the company's Seaprobe. Measurement range of the standard system is 10 to 50 mm with a resolution of O.1 mm. Material calibration is up to 10 m s -1 in steps of 1 m s -1. In general, the system operates automatic signal selection which is protected by an automatic gain control with a range of at least 40 dB and a user accessible swept
Using a focussed, heavily damped (single cycle pulse) 50 MHz crystal, the transducer has a centre frequency of approximately 40 MHz, the overall range extending from 32 MHz up to 48 MHz. When used in conjunction with a high frequency pulser/amplifier, the transducer is capable of resolving 2 0 0 /zm defects in ceramics, says the c o m p a n y - focal spot has been measured as 2 5 0 /~m.
On a digital unit the trace display is built up from a series of dots. This eddy-current unit has capacity for 8 0 0 dots, spread over two 64k RAM. An automatic 'roll' facility erases dots which have been displayed. A 'speed" control adjusts the rate at which dots are displayed, enabling a high definition trace to be produced. Conventional analogue mode is also available. Operation can be in static mode, or for automatic testing with rotating probes, in dynamic mode.
Underwater thickness gauge from Baugh Et Weedon attaches to remote operated vehicles
NDT INTERNATIONAL. OCTOBER 1985
Rohmann (UK) Ltd, Unit 8, Bumpers Farm Industrial Estate, Chippenham, Wiltshire SN14 6 LH , UK
307