Ultrasonic Testing (UT)

The ultrasonic shear wave method is a technique which encompasses the use of predetermined angles for the identification of subsurface anomalies not found directly underneath the transducer itself. Indications within a material and or weldement reflect ultrasonic energy back to the transducer, displaying as an A-scan, in which an operator may assess for relevant information concerning component integrity.

Manual ultrasonic thickness measurements is a technique using high-frequency sound energy to conduct examinations and obtain thickness measurements. A straight beam is introduced into the test object perpendicular to the surface and round-trip time is measured. Quantifiable information can be gathered for detection of localised or general wall-thickness changes.

RTD DTI Trekscan is the first free-floating pipeline in-line inspection tool designed to traverse back-to-back one-dimensional (1D) bends, with an optimum speed of one-metre-per-second (2.2 mph). It can run in pipelines previously considered to be 'unpiggable'. The bi-directional tool measures the return echoes of a transmitted ultrasound beam. The amount of time it takes to receive an echo provides highly accurate information on the remaining wall and enables the detection, characterisation and sizing of metal-loss anomalies. Using the latest ultrasonic technology and high-density transducer-carrier design, most refined petroleum products, water and crude oils can be used as a medium to run this tool.

Time-of-flight diffraction (TOFD) is typically used in conjunction with phased-array applications as a rapid screening tool for the detection and sizing of circumferential- and axial-weld imperfections. TOFD setup involves placing two transducers on opposite sides of the area to be inspected. Sound waves are then refracted into the specimen at angles appropriate to component thickness.

Various locations within a facility have the potential to see the release of product due to hidden corrosion. These locations are referred to as 'difficult to inspect' and include equipment and piping which is partially buried, soil-to-air interfaces, concrete-to-air interfaces, piping encased in a sleeve or concrete, the support-to-equipment interface known as the 'touch point' and the critical area inside a storage tank. Unless the equipment is lifted, taken out of service or un-earthed, the owner/user is usually unaware that issues exist. LoRUS (Long-Range Ultrasonics) is capable of detecting external or internal corrosion within ferrous or non-ferrous material at a distance of up to 90cm (3 feet) depending on the material and its surface condition, corrosion, coatings and temperature.

The Rotoscan system was developed in house by Applus+ RTD for the inspection of girth welds during the construction of long-distance pipelines, both onshore and offshore. Rotoscan detects and measures welding imperfections within the weld and associated heat-affected zone, determining both the circumferential length and the through-thickness dimension. The system couples a low false-call rate (FCR) with flaw-sizing capabilities, a user-friendly presentation in colour using customised software and storage of results.

Ultrasonic phased array provides a fast and reliable solution for flaw detection and characterisation across multiple presentations simultaneously. This technology uses multiple elements fired in quick succession to produce beams that can be steered, swept and focused electronically. Inspections across multiple angles are performed concurrently, creating significant cost savings and providing recordable results for further analysis and/or future inspections. This technique is capable of performing multiple applications including weld quality, corrosion mapping, composites and components of complex geometry. Through use of accurate scan-planning and beam-steering capabilities, probability of detection is heightened while inspection times are reduced to a minimum.

IWEX is a full matrix capture (FMC) technique using ultrasonic (UT) inspection in which individual A-scans are recorded for each and every element of an array transducer, and these A-Scans are processed in a similar way to seismic processing and medical imaging. Advances in computer-processing hardware and software are making these techniques possible in real-time in the field.

IRIS (internal rotating inspection system) is a technique that can be applied to both ferrous and non-ferrous materials and even non-conductive materials like plastics. With IRIS, the remaining wall thickness of tubes can be accurately measured. IRIS inspection is more accurate than other tube-inspection techniques and has the advantage of presenting information about the geometry of defects. Local defects and wall loss on both sides of the tube can be accurately measured. Defects under support plates can be measured without any limitations. The probe used in IRIS examination is made up of a centering device, an ultrasound transducer and a rotating mirror. An ultrasound pulse is generated in the transducer that is mounted in an axial direction, then a 45-degree rotating mirror in the probe will guide the sound bundle towards the tube wall. Next, there will be an ultrasound reflection (echo) at the inner and outer walls of the tube. These echoes are reflected back and processed by the equipment. The time between these two echoes represents the wall thickness of the tube. Knowing the sound velocity in the material under test enables the wall thickness to be calculated. Water is used to rotate the probe mirror and is also needed as a couplant between the transducer and the tube wall. A calibration standard of the same material and dimensions as the tubes to be examined is used to check the IRIS system response in preparation for the inspection. The tubes should also be cleaned to an acceptable standard.

Guided-wave testing has been identified within the industry as an effective pipe-screening technology capable of assessing damaged areas over extended lengths. With the minimal footprint of the technology sensors and bands, areas in which screening was previously hindered by insulation, poor access and coatings are now accessible, reducing the efforts clients need to go to in terms of mobilisation. Recent technological improvements mean that guided-wave testing can be deployed in an array of environments and product temperatures. Results obtained may be analysed on site, enabling technicians to focus their efforts on areas of concern and help reduce the overall costs of system assessment.

Applus+ has developed proven and tested procedures for EMAT inspections in accordance with applicable codes. Our technicians are rigorously assessed and trained, both internally and externally, on data acquisition and interpretation.

Automated ultrasonic C-scan is a technique that utilises ultrasound and mechanised scanners to build a comprehensive plan view of the component being inspected. Typical plan-view imaging is displayed in colour-coded maps according to the thicknesses obtained throughout the inspection area. Calibrated dual-axis encoders provide a scale map to measure the lengths and widths of the indications found.