Automated Ultrasonic Techniques (AUT)

MR Inspection use the following AUT techniques

Weld Inspection

  • Time of Flight Diffraction
  • Phased Array
  • Conventional Pulse Echo
  • Combination of the above

Wall Thickness Surveys

  • Multi-channel Immersion UT from the ID
  • Phased Array Hydroform UT from OD or ID

Flange Pockets

  • Phased Array Sectorial Technique
  • 1. Weld Inspection

  • 1.1 Time of Flight Diffraction

Photo – TOFD Inspection of Main Tube

The principles of TOFD are: -

  • Two transducers (one transmitting & the other receiving) are ‘yoked’ together at a pre-determined 'stand-off’ and are motioned centrally along the weld length. The data is collected using a simple single axis scanning frame with an encased optical encoder for positional information. The data can be enhanced by special software routines and analyzed on a PC based ultrasonic imaging system.

TOFD Data – showing surface breaking flaw.

  • 1.2 Phased Array

The principle of phased array technology is to activate for each ‘firing’ all or some of the transducer elements, which, with the adapted delay laws, contribute collectively to the generation of the beam. The beam is electronically deflected by applying delay laws to different elements of the array.

  • Data collected by a single axis pass - high speed electronic scanning without moving parts.
  • Improved inspection capabilities through software control of beam characteristics.
  • Inspection with multiple angles with a single, electronically controlled probe.
  • Permanent Phased-array probes are composed of several piezoelectric crystals that can transmit/receive independently at different times. To focus the ultrasonic beam, time delays are applied to the elements to create constructive interference of the wavefronts, allowing the energy to be focused at any depth in the test specimen

A Phased array system is based around a specialized ultrasonic transducer that contains many individual elements (typically from 16 to 256) that can be pulsed separately in a programmed pattern.

This enables the following capabilities: -

  • Software control of beam angle, focal distance, and beam spot size. These parameters can be dynamically scanned at each inspection point to optimize incident angle and signal-to-noise for each part geometry.
  • Multiple-angle inspection can be performed with a single, small, multi-element probe and wedge, offering either single fixed angles or a scan through a range of angles.
  • These capabilities provide greater flexibility for inspection of complex geometries and tests in which part geometry limits access.
  • Multiplexing across many elements allows motionless high-speed scans from a single transducer position. More than one scan may be performed from a single location with various inspection angles.

  • 1.3 Combined TOFD/Phased Array

  • 1.4 Combined TOFD - Automated Pulse Echo

For the inspection of welds on the auxiliary lines – a motorized dual axis scanning tool is deployed from the ID

  • A self driven motorized scanner using a combination of TOFD and Pulse Echo ultrasonic techniques and integral video camera to confirm weld location is inserted to the pipe.
  • System can be deployed in pipe with Internal Diameters from 3.3” to 5.5”.

  • Wall Thickness Examinations are carried out using purpose build scanners in combination with an Omniscan MX2 Data Acquisition system. The system continuously records ultrasonic thickness measurements as the scanning head is moved along the inspection surface of the pipe. The recorded UT thickness information is presented as an A-scan trace, a digital thickness measurement and a B-Scan thickness profile. Inspection results can be viewed in real time in the field or recalled for post inspection analysis at a later date… This can be carried out from either the ID or the OD where access is permitted

  • 2.1 Principle Tube – Immersion
  • Wall thickness data is collected along the entire length of the tube at 8 circumferential locations.
  • The data is displayed in a B-scan format showing the wall profile.

  • 2.2 Auxiliary Line – Immersion UT
  • Wall thickness data is collected along the entire length of the tube at 4 circumferential locations.
  • The data is displayed in a B-scan format showing the wall profile.

  • 2.3 Hydroform Corrosion Mapping
  • The Wall Thickness/Corrosion surveys can be carried out by deploying a hydroform phased array system from the OD.
  • Data can be collected down to a resolution of 1mm with a depth accuracy of approximately 0.25mm.
  • Coverage can be seen on topographical plan view and end view sections.
  • Images coutesy of Olympus

  • 3 Flange Pocket Inspection
  • To detect cracking, pitting etc. in riser flange pockets with out the requirement to remove the auxiliary lines (and inserts), a validated Inspection using Phased Array sectorial scanning is carried out from both the OD and the ID of the flange.
  • Flange Pocket – Raw data set from Phased Array Inspection