Advanced NDT
Inspection
Advanced Non-Destructive Testing
Phased Array Ultrasonic Testing (PAUT)
Phased Array Ultrasonic Testing (PAUT) is an advanced non-destructive testing technique used to inspect materials for internal defects. PAUT employs an array of ultrasonic transducers arranged in a single probe. By controlling the timing and phase of the Ultrasonic pulses emitted from each transducer, the system can electronically steer and focus the ultrasonic beam in various directions and depths without moving the probe physically. This ability allows for detailed scanning and imaging of complex geometries and large areas, providing high-resolution and multiple views as A-Scan, B-Scan, S-Scan and C-Scan.
Time-of-Flight Diffraction (TOFD) Ultrasonic Testing
Time-of-Flight Diffraction (TOFD) is a modern and highly accurate ultrasonic Testing Technique employed for detecting flaws in weldments to ensure accuracy of sizing. The use of longitudinal waves, in lieu of shear wave techniques made TOFD more accurate than conventional methods.
Time of flight diffraction (TOFD) uses ultrasonic Transducer on opposite sides of the weld—one for sending a ultrasonic beam through it and another for detecting reflected or diffracted signals from any defects. TOFD accurately detects and sizes flaws by measuring the time it takes for these signals to travel, even when those defects are misaligned with respect to the original beam of that initial probe.
Long-Range Ultrasonic Testing (LRUT)
Long Range Ultrasonic Testing (LRUT), also known as guided wave ultrasonic testing, is an advanced and efficient non-destructive testing method for inspecting long lengths of pipe. Utilizing low-frequency ultrasonic guided waves (ranging from 5 to 250 kHz), LRUT can screen hundreds of meters of pipeline from a single location in a single day, inspecting 100% of the pipe wall. This is achieved by fitting a ring of transducers around the pipeline, which generates and receives ultrasonic waves along the pipe’s length.
The low frequency helps generate non-dispersive waves, reducing attenuation and enabling long-range inspection. These non-dispersive waves travel through the pipe wall and reflected back by the defects such as corrosion and other anomalies. These reflected waves are received by the transducers and produce the signal on the screen.
Short-Range Ultrasonic Testing (SRUT)
Short Range Ultrasonic Testing (SRUT) is a specialized application of guided ultrasonic sound waves using special types of probes. When the ultrasonic waves hit discontinuities, the mode-converted ultrasonic waves are reflected back and received by the transducer. This technique utilizes higher frequency ultrasonic waves, resulting in higher sensitivity and resolution.
A specially programmed ultrasonic focal law is used to generate short-range guided waves. The probe is usually scanned over a region that is easily accessible and clean from surface irregularities, facing in the direction of the region of interest, which is usually inaccessible due to support structures or the geometry of the test object.
Pulsed Eddy Current Testing (PECT)
Pulsed Eddy Current (PEC) is an electromagnetic inspection technique used to detect wall loss in ferromagnetic materials like carbon steel and cast iron. It offers a measure of wall thickness over the probe’s footprint without direct contact with the surface. To generate and capture PEC, a magnetic field is first created by an electrical current in the coils of the probe. This field penetrates through the cladding and any non-conductive insulation (such as concrete, silicate, insulation with a weather jacket, or marine growth) and stabilizes within the component thickness. When the emission is cut off, this abrupt change induces eddy currents that are captured by the probe.
PEC can be applied to in-service assets and can detect damage through insulation and fireproofing, making it an effective tool for assessing corrosion-under-insulation (CUI) and flow-accelerated corrosion (FAC). It is ideal for petrochemical plants, refineries, power generation, and marine applications, including tank floors, pressure vessels, piping systems, offshore platforms, risers, and ship hulls. PEC provides benefits such as minimized accessibility issues and effectiveness through thick materials.
Alternate Current Field Measurement (ACFM)
Alternating Current Field Measurement (ACFM) is a non-destructive testing (NDT) technique used to detect surface-breaking cracks in metals. It operates by inducing an alternating current into the surface of a conductive material, creating an electromagnetic field. When a crack is present, it distorts the electromagnetic field, and this distortion is instantly detected by the ACFM sensor, generating a signal on the equipment screen that provides precise measurements of the crack’s length and depth.
Magnetic Flux leakage Testing (MFL)
Magnetic Flux Leakage (MFL) Testing is widely used to detect surface and near-surface defects in ferromagnetic materials, such as steel, commonly found in pipelines, storage tanks, and other critical infrastructure. The MFL principle involves magnetizing the material under inspection by passing a strong magnetic field through it. When the material is free from defects, the magnetic field flows uniformly.
However, if there are discontinuities, such as cracks, corrosion, or pitting, the magnetic field is disturbed, causing a portion of it to leak out of the material. This leakage field, occurring at the defect site, is detected by sensors placed close to the material’s surface. These sensors capture the leakage signal, which is then analysed to determine the presence, size, and location of the defect.
Tube Testing Services
Eddy Current Testing (ECT)
Eddy Current Testing utilizes electromagnetic induction to detect defects in tubes. The principle of Eddy Current Testing involves inducing an alternating current into a probe coil, which creates a magnetic field. When this coil is placed near a conductive tube, it generates circulating currents (eddy currents) within the tube. Any flaws, such as cracks, corrosion, or wall thinning, disrupt these Eddy Currents, causing a change in the coil’s impedance. This change is measured and analysed to detect and characterize defects.
It is the fastest way to assess the condition of non-ferrous tubing in heat exchangers, steam generators, condensers, feed water heaters and evaporators. The inspection is performed swiftly and efficiently, with data collection speeds faster than any other inspection method. Analysis is performed on site and remote to provide immediate results. It is an efficient method of determining the condition and lifespan of tubes, particularly in the power generation, petrochemical, chemical, fertilizer, and air conditioning industries. The technique is used to detect corrosion, pitting, cracks, erosion, and other changes to the interior and exterior surfaces of the tube.
Eddy Current Array Testing (ECA)
Eddy Current Array (ECA) is an advanced version of conventional eddy current testing (ECT), offering improved detection capabilities, speed, and coverage. The Eddy Current Array probe utilizes several individual coils placed around the circumference of the probe and excites them in sequence to eliminate interference, allowing for 100% coverage around the tube’s internal diameter.
ECA can inspect a larger area in a single pass, improving defect detection, especially for small or complex flaws, and providing higher resolution images, including a 3D C-scan of the tube showing the overall topography of any defects that may be present, for more accurate analysis. This technique is good for the detection of axial crack, circumferential cracks, and provides better accuracy for gradual wall losses. It is versatile and can be used on various tube materials and configurations, making it suitable for different industries. ECA tube testing is widely applied in inspecting tubes of heat exchangers, condensers, and boilers in various industries.
Internal Rotary Inspection System (IRIS)
IRIS is an ultrasonic technique employed to evaluate the remaining wall thickness of tubes and pipes. This technique is suitable for both ferrous and nonferrous materials. An IRIS probe is inserted into a tube flooded with water. The probe is fitted with a transducer that generates an ultrasonic pulse along a path parallel to the axis of the tube. A rotating mirror directs the ultrasonic pulse into the tube wall. The mirror is driven by a small turbine that is rotated by the pressure of water pumped into the tube. The ultrasonic pulses are reflected by the inner-diameter (ID) wall and outer-diameter (OD) wall of the tube, and the time-of-flight difference between the two diameters is used to calculate the wall’s thickness.
Magnetic Flux Leakage Testing (MFL)
Magnetic Flux Leakage Testing (MFL) is a technique used for inspecting tubes made of ferrous materials, typically applied as a fast-screening method when small diameter pitting is expected. The MFL probe contains permanent magnets that create a magnetic flux field in the tube wall. Defects disrupt the magnetic field, causing some flux to leak out of the tube wall, which is then detected by the coils and Hall-effect sensors in the probe.
The size of the leakage field, influenced by the probe’s pull speed and the defect’s shape, dimensions, and location, is presented on a computer screen. Benefits of MFL testing include its ability to inspect finned tubes, applicability to all ferromagnetic materials, good sensitivity to ID pitting, corrosion, erosion, and circumferential cracks. MFL is ideal for the rapid inspection of aluminium-finned tubes and all ferromagnetic heat exchanger tubes, including heat exchanger tubes and air fin fan coolers.
Near Field Testing (NFT)
Near Field Testing (NFT) is an electromagnetic technique which is specifically designed to inspect air cooler (Fin Fans) tubes found in the Oil & Gas industries The technology employs two coils—a transmitter and a receiver—where the receiver is positioned near the transmitter to take advantage of the near-field zone, inducing strong eddy currents axially and radially in the tube wall. The basic probe consists of one driver coil and three receiver coils, providing both absolute and differential signals proportional to defect depth and size.
NFT offers several benefits, including the ability to detect discontinuities near support plates and tubesheet with high sensitivity, and its speed compared to other electromagnetic testing methods. NFT is not influenced by external support structures or tubesheet and it can detect both pits and overall wall loss. NFT is ideal for inspecting fin-fan heat exchanger tubes, particularly aluminium-finned carbon steel tubes, and is excellent for detecting internal discontinuities such as corrosion, erosion, pitting, and axial cracking.
Near Field Array Testing (NFA)
Near Field Array Tube Testing (NFA) is an advanced electromagnetic testing method used to detect discontinuities on the internal surfaces of fin-fan type tubes and ferromagnetic (carbon steel) heat exchanger tubes. Near Field Array probe employs up to 30 coils activated in sequences. An additional tangential coil in Near Field Array allows for detailed data acquisition and detection of discontinuities in all directions.
This method is particularly efficient for inspecting aluminium-finned carbon steel tubes, which are challenging to inspect due to the interference of external aluminium fins with signal quality. It can accurately detect and locate common discontinuities, such as internal pitting, cracks at the tubesheet, internal erosion, and resultant wall loss. Advantages of Near Field Array include providing 2D and 3D ‘C’ scan images for precise measurement of discontinuities size and location, measuring volumetric discontinuities as small as 3mm in a single pass, and detecting both axial and circumferential cracks. It is applicable to a wide range of uses, including ferromagnetic heat exchangers and aluminium fin fan coolers.
Remote Field Testing (RFT)
Remote Field Tube Testing (RFT) is an electromagnetic testing used to inspect ferromagnetic tubes and pipes such as those in heat exchangers, boilers, and piping systems. The principle of RFT involves generating an electromagnetic field inside the tube using an exciter coil. This field travels through the tube wall, re-enters the tube on the opposite side, and is detected by a receiver coil positioned at a specific distance from the exciter.
Any changes in the electromagnetic field due to defects, causing changes in the signal detected by the receiver. The benefits of Remote Field Testing include its suitability for inspecting ferromagnetic materials and its equal sensitivity to defects on both the inner and outer surfaces. It is highly sensitive to variations in wall thickness. It can operate effectively with lower fill factors compared to Eddy Current Testing (ECT). Additionally, it can detect large-area discontinuities such as steam erosion and baffle wear, making it a versatile and reliable inspection method.
Digital Radiography (DR)
Digital Radiography (DR) is an advanced form of industrial radiography imaging where digital detectors are used instead of traditional radiographic film, offering immediate image preview and availability. The working principle involves the use of a digital detector to capture radiographic images, which are then converted into digital signals and processed by a computer software to produce high-resolution images.
This method eliminates the need for chemical processing and allows for the enhancement and manipulation of images for better accuracy and resolution. Advantages of DR include faster image acquisition and processing, reduced radiation exposure for radiation workers, enhanced image quality with the ability to digitally enhance and magnify images, and improved storage and retrieval through digital archiving. The technique can detect discontinuities in a range of materials including aluminium, steel, stainless steel, duplex stainless steel, plastics, and composites. Digital radiography is used in all industry sectors, particularly for assessing piping, pressure vessels, and valves etc.
Infrared Thermography (IR)
Thermography Testing used to detect and measure small temperature differences to help find deterioration in assets and plant sites. Thermography can support the maintenance of industrial plants and equipment with its fast and cost-effective application. The working principle involves using an infrared camera to capture the infrared radiation emitted by an object’s surface, which is then converted into a thermal image or thermogram.
Magnetic Rope Testing (MRT)
Magnetic Rope Testing (MRT) is a crucial method for ensuring the safety of steel wire ropes used onshore and offshore. By fully magnetizing a section of the rope and detecting changes in the magnetic field caused by defects like broken wires, corrosion, wear, or mechanical damage, MRT provides a precise assessment of the rope’s internal condition. This lightweight and portable equipment allows for on-the-spot inspection while the rope is in service, utilizing strong rare earth magnets and sensors to detect discontinuities. MRT measures the Loss in Metallic Area (LMA) and identifies Localized Faults (LF).
Acoustic Emission Testing (AET)
Acoustic Emission Testing (AET) is a non-destructive method used to monitor the integrity of structures and materials by detecting transient elastic waves generated from localized sources of strain energy under stress. This technique is effective for the real-time identification of active damage such as crack growth, fiber breakage, and corrosion. Acoustic Emission sensors (transducers) detect high-frequency signals from structural defects, and the results are analyzed to accurately locate defects. It provides insights into defect severity and origin, identifying common issues such as active corrosion, crack propagation, hydrogen-induced defects, leaks, and stress corrosion cracking.
3D Laser Scanning
3D Laser Scanning is a vital tool in construction, engineering, and architecture, transforming real-world sites into digital 3D models. This technology captures the shape, size, and details of objects or environments in three-dimensional space using laser beams. A 3D scanner emits laser beams onto the surface being scanned, measuring the distance between the scanner and the object’s surface by calculating the time it takes for the laser beams to reflect back.
Ground Penetrating Radar (GPR)
Ground Penetrating Radar (GPR) is a non-destructive geophysical method using radar pulses to image the subsurface, widely applied in construction, archaeology, environmental studies, and utilities management. GPR operates by emitting high-frequency radio waves into the ground through a transmitting antenna; these waves reflect back to a receiving antenna upon encountering subsurface materials or objects. The return time is measured to create a subsurface profile.
