Advanced (NDT)

Time of Flight Diffraction(TOFD)

The non-destructive testing method known as Time of Flight Diffraction (TOFD) is an advanced technique commonly used in weld inspection. As part of the Ultrasonic testing family, TOFD provides a highly accurate solution to flaw detection and sizing for both pre-service weld inspection and for in-service inspection.

As TOFD uses diffracted signals, the detection of defects is not affected by geometry, making it very useful for detection of volumetric flaws (e.g. pits, voids and inclusions) and planar flaws (cracks and laminations). Other applications beyond weld quality assessment include:

• Pipe scanning for the detection of material anomalies, and in-service defects.
• Pressure vessel scanning for detection of MIC, SCC and other process related defects.
• Bonded clad materials to identify dis-bonds and cracking in the cladding or parent material.
• Storage tanks for detection of SCC in the welds or parent material.
• Accurate monitoring of defect growth, with repeatable scans for comparison.

TOFD testing is often performed in conjunction with other advanced NDT techniques, specifically with Phased Array techniques given PAUT’s ability to access other weld elements such as root and caps.

Advantages of TOFD

The advantages of TOFD include:

• TOFD accurately detects and sizes many sub-surface features and is not affected by defect orientation or geometry.
• TOFD is a rapid and highly reliable testing method that can be used to detect cracks and defects and monitor these defects over time.
• It can be carried out whilst production is occurring, which removes any downtime and efficiency concerns.
• TOFD can be used up to 120°C with special probe wedges and couplant.
• Produces result quickly along with accompanying graphics and full data recording.
• A permanent record of scan data can be maintained.

Drone Inspections

Remotely Piloted Aircraft (RPA), Unmanned Aerial Vehicles (UAV), or as they are most commonly known, drones are a market-leading inspection solution that bring extend the reach of inspection, without placing personnel in harms way. The use of UAV inspections can negate the need for scaffolding, working at heights, EWP or rope access, providing substantial customer cost savings.

ALS has maintains one of the largest fleet of drones which cover a diverse inspection capability for both internal and external inspections.

Our fleet includes internal inspection drones for visual inspection and more sophisticated platforms capable of carrying different payloads, such as Thermography cameras, Laser Scanners and Spot Thickness testing payloads Our team also provides drone based automated photogrammetry model capture.

ALS have multiskilled pilots who are each certified to the relevant local laws and regulations required to fly drones commercially. Every pilot receives extensive in-house training and is broadly experienced across a range of asset, inspections and industries.

Our internal inspection services include Enclosed Beyond Visual Line of Sight (E-BVLOS) and Extended Visual Line of Sight Class 1 (EVLOS Cl1).

Electro Magnetic Acoustic Transducer (EMAT)

Electro-Magnetic Acoustic Transducer (EMAT) offers a reliable solution to detecting corrosion and isolated pitting screening in difficult to access areas.

EMAT is a dry coupled ultrasonic non-contact technique that is based around the use of electro-magnetic energy to generate ultrasonic sound wave in the component being tested. Due to this couplant-free feature, EMATs are particularly useful in harsh environments - think hot or cold.

Applications of EMAT

• Dry coupled thickness measurement.
• Possible to inspect temperatures up to 200˚C.
• Corrosion under supports using MRUT-A mode.
• Flaw detection in steel products.
• Detection of pinhole like defects.
• Plate lamination defect inspection.
• Pipeline in-service inspection and direct assessment of partially excavated piping.
• Scanning of piping low to the ground and resting on the ground.

Advantages of EMAT

• EMATs use a non-contact testing method.
• EMATs do not require couplant for transmitting sound.
• EMATs can inspect through thin coatings and are not affected by minor surface roughness.
• EMATs offer easy probe deployment – not having wedges or couplant, Snell's Law of Refraction does not apply and the angle of the probe does not affect the direction of propagation. This makes the probes easier to deploy.
• EMATs can screen for corrosion from unlagged locations up to 3m each way (6m in total per scan).
• EMATs can scan piping to detect corrosion at the Air to Ground Interface (AGI's).

Long Range Ultrasonic Testing (LRUT)

Long Range Ultrasonic Testing (LRUT) is an advanced non-destructive testing technique. LRUT uses low frequency ultrasonic modules and works by creating an ultrasonic wave form that travels both longitudinally and circumferentially, allowing long lengths of piping to be scanned. The technique is used to detect and analyse ultrasonic signals received as a result of metal loss such as corrosion and erosion.

LRUT, also known as Guided Wave Ultrasonic Testing (GWUT), gives pipeline operators a comprehensive look at their pipeline’s condition.

LRUT applications include:

• Pipework, including examining for Corrosion Under Insulation (CUI) covering many metres from one scan location.
• Long steel cylindrical elements such as steel piles and structural cylindrical columns.
• Corrosion Under Pipe supports (CUPS).
• Buried piping, such as piping running under roads.
• Piping going through bund walls and other concrete structures.

Advantages of LRUT

LRUT is an excellent screening tool in long components, such as pipework, for evidence of localised thickness loss, including external and internal corrosion pits. Additional advantages include:

• The ability to measure significant pipe lengths from a single point.
• There is no need for scaffolding installation, coating removal or excavation.
• The ability to inspect pipes at temperatures up to 100°C.
• The inspection can be conducted whilst the asset is in service, removing possible production losses and downtime.
• Rapid inspection time and rapid results.

Phased Array Ultrasonic Testing (PAUT)

Phased Array Ultrasonic Testing (PAUT) is a non-destructive testing method that utilises an array of ultrasonic elements to create a tailored ultrasonic wave form based on wave physics principles. Each element is controlled individually by the pulser so delays can be introduced to phase the firing order of the elements. This allows the ultrasonic beam to be steered, focused or both, and increased flexibility in inspection.

PAUT has applications in most assets and structures where specialised flaw inspection is required. ALS optimised PAUT applications for these critical assets include:

• Tank construction welds.
• Bolt inspection for corrosion and breakage.
• Shafting cracking in complex shaft geometry including hollow bore shafts or axels.
• Non-Intrusive Inspection (NII) of upstream oil and gas equipment.
• Complex geometry scanning, such as nozzle to shell welds.
• Solid shafts and pins for detection of cracking.
• Turbine components for detection of critical cracking and corrosion.

Advantages of PAUT

The advantages include:

• PAUT has flexibility when assessing unique geometries.
• Inspection is performed in-situ, eliminating disassembly and transport costs, and unnecessary downtime.
• Accurately detects and sizes many sub-surface defects, with high-probability to detect developing cracks.
• Capable of working for many different material types.
• A permanent record of the inspection is maintained.
• PAUT requires careful planning and set-up, but once done can provide an efficient inspection.
• ALS can offer PAUT at temperatures up to 150°C using a specially developed procedure and temperature specific focal law management.

Photogrammetry

Photogrammetry refers to the highly effective, non-contact process of transforming photos of an asset into a 3D digital model (Digital Twin).

The process of photogrammetry requires overlapping photographs of the physical asset, space or structure to be taken. To be successful the asset is captured from many different angles and locations. It is critical all lines of sight required to be modelled on the asset are captured. These images are then processed into a 3D digital model that replicates this photographed physical asset.

The 3D digital twin, or reality model, can be used as the digital representation of the as-built physical asset. It can be re-captured periodically to track changes, have external data applied to gain insights, or can be continually manipulated throughout the asset’s lifecycle to reflect any physical changes.

Photogrammetry can be used to capture extremely accurate, realistically textured models of:

• Buildings
• Structures
• Pressure vessels
• Archeological sites
• Landscapes, if the images are taken from the air

Advantages of Photogrammetry

The advantages to using Photogrammetry include:

• The ability to rapidly collect data, which that can be collected with relative ease.
• The ability to create a highly accurate digital twin, which can be manipulated repeatedly, and provide ongoing insights.

ALS as significant experience in constructing photogrammetry models to support asset integrity programs. Our methods include:

• Handheld or ground based photogrammetry
• Aerial (UAV) based photogrammetry
• Mixed source photogrammetry

Handheld or Ground Based Photogrammetry

Handheld or ground based photogrammetry refers to images captured with handheld cameras or tripod-mounted cameras. It is better suited for capturing smaller objects or areas at very high resolution.

Pulsed Eddy Current Testing (PECT)

Pulsed Eddy Current Testing (PECT) is used for the detection and assessment of the gradual thinning on ferromagnetic materials, due to failure mechanisms such as general erosion, wear and corrosion. PECT offers a valuable screening tool for corrosion, erosion, and wear in industrial assets.

PECT can be used to measure ferromagnetic base material thickness, through the following materials:

• Concrete - with or without re-enforcement bars and, in some cases chicken wire.
• Non-metallic coatings and insulation – for example paint, plastics, bitumen, epoxy, dirt, deposits, marine growth, Rockwool, with or without chicken wire and/or metallic protection (weather-jacketing or sheeting).
• Aluminum sheeting
• Other non-magnetic metal insulation covers excluding aluminum
• Refractory
• Fire proofing materials

PECT has a wide range of applications and ALS has specific expertise in the following areas:

• Detecting flow accelerated corrosion on power station piping.
• Through marine growth on jetty legs at loading areas and pipeline jetties.
• Fireproofing on pressure vessels.
• Detecting corrosion on lagged piping & vessels (Corrosion Under Insulation).
• Scanning through very hot uninsulated components, such as valve bodies and high temperature heavy wall equipment.
• Scanning through “corrosion blisters”.

Restricted Access Phased Array (RAPA)

Restricted Access Phased Array (RAPA) is an advanced non-destructive testing technique unique to ALS that has allows online inspection of critical assets. The technique has three primary applications:

• Tank Annular Critical Zone (Tank Annular Plate) in-service corrosion screening
• Corrosion under pipe supports (CUPs)
• Air-to-ground interface corrosion scanning (e.g. pipelines, structural columns and posts).

Advantages of RAPA

RAPA is an efficient semi-quantitative screening method which produces similar results to the Short Range Guided Wave (SRGW) technique. The specific RAPA advantages include:

• Can detect shallow defects such as scallop and poor reflector corrosion.
• Can perform scanning with the plant or asset on-line, at temperatures below 100°C.
• The results can be seen in real time.
• Can provide accurate measurement of the corrosion area, providing length and breadth measurements, through encoded scanners.
• Minimal dead zone in front of probes compared to other techniques, such as Long Range UT.
• There are a wide range of difficult access applications.
• The inspections can be conducted using rope access solutions.

Saturated Low Frequency Eddy Current (SLOFEC)

Saturated Low Frequency Eddy Current (SLOFEC) couples efficient and effective corrosion screening with high-quality, defect reports. The technique combines eddy current principles with a magnetic field to provide a reliable, non-destructive testing solution. SLOFEC inspections are an integral element in a consistent maintenance program for tanks, pipes and beyond. It is integral as the inspection monitors for defects that if left unnoticed could cause avoidable financial expenses, operational delays or pollution to the environment.

The main applications of this technique are the inspection of large ferro-magnetic surfaces such as:

• Storage tank floor, annular, roof and wall plates
• Pipelines from 4” diameter upwards
• Plant process piping
• Pressure vessels

Advantages of SLOFEC

SLOFEC techniques provide the ability to rapidly screen large surface areas of magnetic materials and can accurately detect very small and isolate corrosion. The main technical advantages of the SLOFEC technique include:

• Capable of inspecting ferromagnetic and non-ferromagnetic materials (outer surface damage only).
• Efficient inspection time which requires minimal surface preparation.
• High inspection temperature which ranges up to 150°C.
• Capable of detecting corrosion within a large wall thickness range.
• Has unique and useful feature of differentiating between defects on the top-side, under-side and through holes.
• Capability of real time scanning.
• Very high Probability of Detection (POD) for detection and especially useful for the detection of MIC (Microbial Induced Corrosion).

3D Laser Scanning

Laser scanning is a highly customisable process used to digitally capture a physical asset. When used for wear analysis, it is typically used to capture both the worn and unworn state of the equipment. The two scans are then overlaid and a dimensional difference analysis is performed, thus indicating wear patterns.

Advantages of 3D Laser Scanning

• Speed as the on-site time is only a fraction of conventional methods.
• Accuracy as the typical tolerance is +/- 2mm.
• Retention of information as digital scan files can be stored and used over time.

ALS WearManager is a comprehensive wear management advisory offering that is performed post-scanning, off-site. When the comparison scans for an asset are available, ALS’s engineering services can estimate the expected remaining life of the wearing components and provide a comprehensive wear assessment to support wear liner management if needed.