For over the past 30 years Time-Of-Flight Diffraction (TOFD) technique of the UT method of NDT has been developed swiftly and has become an irreplaceable one when carrying out welded joints testing. TOFD assures a great accuracy for comfortable measuring the critical size of defects. The accuracy of better than ±1mm can be obtained in a wide range of material thickness.
The system is designed for testing long welded joints of pipes, tanks, vessels, cisterns, ship hulls, bridges, etc. using TOFD technique. Circumferential welds with a diameter from 12 in (300 mm) can be inspected on cylindrical objects. On cylindrical, spherical, as well as complex shaped objects with a radius of surface curvature from 16 ft (5 m) to flatness, the system is capable of testing long welds in any direction. Objects with wall thickness from .25 to 12 in (from 6 to 300 mm) can be examined with the help of appropriate probes. Depending on the inspection task, the TOFD MAN TM system can be complemented with another scanner. The number of probe pairs can vary from 1 to 4. For good coupling, it is advisable to use an external couplant supply system. In this case, a water hose is attached to the scanner. But if absolute mobility is needed, coupling media can be applied to the object before testing, or a test piece can be continuously showered with water
All the equipment is placed in the operator’s utility vest, which does not impede the movement, also when performing an inspection at height (climbing, rope access). The standard system kit comes with an 8 to 10-hour battery to be placed in the vest. The scanner is lightweight and easy to operate. It ensures a handy probe setup.
During setup and testing, all setup data are transferred to a remote PC (laptop or tablet) via Wi-Fi. A system for protecting the integrity of test data is provided, while they are fully stored inside the TOFD module and transferred to PC at the end of testing. If required, it is possible to use a wire connection to transmit data to PC.
Main advantages of TOFD are:
The TOFD Man is a compact and reliable test system, which guarantees stable scanning results. Magnetic wheels and spring-loaded probe carriers with a self-positioning system ensure transducer stability on the object surface which results in good coupling necessary for reliability of test results. The scanner is easy to drive and does not fall from the object even when upside down. The System is composed of the elements that are placed in the utility vest: – TOFD Ethernet module, – Wi-Fi module, – rechargeable battery pack. The cases of the TOFD module and the battery pack are shockproof. All the equipment has a protection rating of IP65. The scanner design ensures that if the scanner falls down, the main impact will come to the scanner structure elements saving the electronics. The storage battery provides 8-10 hours of TOFD Man system operation.
|Testing objects parameters|
|Thicknesses||per one path .25 – 2 in (6 – 50 mm);
with probe replacement per several paths 50 – 300 mm
|Diameter for cylindrical objects||from 12 in (300 mm) to flat|
|Diameter for spherical objects||from 16 ft (5 m) to flat|
|Scanner TOFD 2.2 Lite|
|Dimensions (L×W×H)||450 × 240 × 120mm|
|Number of TOFD pairs||1|
|Coupling liquid supply||individually for each probe|
|Compatible probes and wedges|
|Angles (L-wave)||45°, 60°, 70°|
|Number of cursors||2|
|Types of cursors||Conventional (cross) Hyperbolic|
|Indications parameters||X, X1, X2, dX Z, Z1, Z2, dZ Type (Point, Top, Bottom, Middle, Volumetric) Amplitude|
|Units||mm / in / us|
|Pulser and Receiver||2 × BNC|
|Voltage (SWP)||20 V, 30 V, 40 V, 50 V, 80 V, 100 V|
|Energy (SWP)||20 ns to 500 ns with 10 ns step|
|PRF||from 15 to 2000 Hz|
|Range||Up to 100 us|
|Delay||Up to 100 us|
|Gain||0 to 110 dB, with 0.1 dB step|
|Max signal input||20 V p-p|
|Bandwidth||0.2 MHz – 27 MHz|
|Filters||1 MHz, 2-3 MHz, 4-5 MHz, 10 MHz, 15 MHz, Full band|
|Signal Average||2x / 4x / 8x / 16x / 32x|