NDT Services

Alternating current field measurement (ACFM) is an electromagnetic technique used for the detection and sizing of surface breaking cracks in metallic components and welds. It combines the advantages of the alternating current potential drop (ACPD) technique and Eddy Current Testing (ECT) in terms of defect sizing without calibration and ability to work without electrical contact respectively.

The Alternating Current Field Measurement – or ACFM – technique was specifically developed to detect and size surface-breaking defects on and around rough welds through several millimetres of non-conductive coating. This is a key advantage because just the costs associated with paint removal, post-MPI re-blasting, and recoating are typically four or five times more expensive than the MPI itself.

While the main failure point in storage tanks is corrosion in the floor plates, from either the top surface or from the underside, the welded sections are also a direct source of damage mechanisms. ACFM is proving itself as the most cost-efficient and trusted method for inspecting storage tank welds to supplement corrosion mapping, successfully detecting large cracks often missed by MPI.

You can’t deny the cost savings of ACFM over MPI; overall, ACFM jobs are typically six times less expensive than their MPI counterparts while providing the added value of a more reliable inspection with data-rich information to pass along to the asset owner.

Benefits:

• Applicable for base material or welds, ferritic or non-ferritic conductive metals
• Can be used on hot surfaces, underwater, or in irradiated environments
• Provides both depth and length information
• Accurate sizing of defects up to 25mm in depth
• Requires minimal surface preparation and can be applied over paint and other coatings
• Applicable for under water inspection as well as normal inspection
• Inspection data can be stored and analysed offline
• Inspection can be encoded
• Provides a permanent record of indications
• Ongoing monitoring capability
• High temperature capability

Applications:

• Applicable for base material or welds, ferritic or non-ferritic conductive metals
• Can be used on hot surfaces, underwater, or in irradiated environments
• Provides both depth and length information
• Accurate sizing of defects up to 25mm in depth
• Requires minimal surface preparation and can be applied over paint and other coatings
• Applicable for under water inspection as well as normal inspection
• Inspection data can be stored and analysed offline
• Inspection can be encoded
• Provides a permanent record of indications
• Ongoing monitoring capability
• High temperature capability

Eddy Current Testing (ECT) is used to measure the intensity of electrical currents in a magnetic field. Eddy current testing utilises AC current in a coil near or around a specimen, inducing circulating eddy currents in the material's surface. Flaws and material differences affect these currents, altering the coil's current via mutual induction. Flaw detection relies on measuring electrical changes in the coil, often focusing on voltage changes. Key factors influencing eddy currents include specimen conductivity, magnetic permeability (for ferromagnetic materials), coil-specimen distance, AC frequency, and dimensions. Calibration on test specimens is common, and eddy current testing is highly sensitive to flaws. Equipment ranges from basic meters to advanced computer-programmed systems, with applications including crack detection, component sorting, and metal quality control.

Eddy current inspection is often used to detect corrosion, erosion, cracking and other defects in tubing using electromagnetic induction. A probe is inserted into the tube and pushed through the entire length of the tube. Eddy currents are generated by the electromagnetic coils in the probe and monitored simultaneously by measuring probe electrical impedance.

3D inspection utilises the latest developments in the market offering high definition surface mapping using a combination of visible light or low laser. It can act as a depth pit gauge adding a benefit of repeatability to the inspection. By using 3D inspection we can map large complex shapes with reduced time on site.

Sonomatic RAIS offers Pulsed Eddy Current (PEC) using Eddyfi® Lyft™ inspection technology. The system allows measurements to be taken through any non-conductive materials such as insulation, protective coatings, concrete, and marine growth, without requiring any direct contact with the inspection surface. State-of-the-art instrument; real-time C-scan imaging; fast data acquisition (up to 15 readings per second) with grid and dynamic scanning modes; and great flexibility thanks to extension cables, probe shoes, and an extension pole. Using the Lyft probes, Sonomatic can scan through thick metal and insulation.

Post Weld Heat Treatment is an essential part of both the operation and maintenance of assets in the fabrication, oil & gas and power industry. The welding process can unintentionally weaken equipment by imparting residual stresses into a material which can lead to reduced material properties. This said, Post Weld Heat Treatment (PWHT) is a method used for reducing and redistributing said residual stresses in materials ensuring that the material strength is retained after the welding course. It is also used as a method of hardness control or even to enhance material strength.

In some standards PWHT is compulsory for certain grades or thicknesses, otherwise it is dependent on the material type and the service requirements. Other factors that impact the need for this Inspection are the welding parameters, the likely mechanism failure, its alloying system, or whether it’s been subject to Heat Treatment previously. Generally, the higher the carbon content and/or the higher the alloy content in materials, the more likely it is to need PWHT after welding activities.

If PWHT is neglected, residual stresses can combine with load stresses to exceed materials limitations which can lead to weld failures, and weld cracks and make a weld vulnerable to brittle facture.

At Sonomatic’s NDT Facilities, we have large specified areas for Heat Treatment activities which hold permanent Heat Treatment machines and have the allocated floor space to accommodate all sizes of pipework. In addition, utilising portable equipment, we can offer PWHT at our client's sites at both onshore and offshore locations. At our NDT facilities, we also provide the Non-Destructive Testing required for both Pre and Post PWHT, including magnetic particle inspections and radiographic inspections.

Ultrasonic Testing is a non-destructive testing method used for obtaining wall thickness measurements to determine any erosion and/or corrosion damage and for identifying flaws including weld root erosion and fatigue cracking in welded components.  UT Inspection works for determining both internal and external defects and is an accurate measuring tool for establishing the exact location and depth of noted flaws.

These are normally applied to structures that are more often subject to corrosion, erosion, and internal defects such as laminations or inclusions.

They are also applied to welds to detect fabrication defects and when in-service to detect weld root erosion and fatigue cracks. These techniques rely on favourable orientation of the imperfections to be noted relative to the direction of the applied ultrasound. The geometry of the imperfection such as pitting is also a main consideration.

Sonomatic technicians are qualified for the full range of UT testing techniques from:

• Thickness Checking (UT 3.0).
• Ultrasonic Testing of Welds (UT 3.1 3.2).
• T-Pieces (UT 3.7).
• Nozzles and Nodes (UT 3.8 3.9).
• Forgings and Castings.

Electro Magnetic Acoustic Transducer (EMAT) is an Ultrasonic Testing (UT) technique that generates the sound in the part inspected instead of the transducer. An EMAT comprises a magnet and an electrical coil. When a current is passed through the coil, eddy currents are induced in the component under test. The static magnetic field exerts a force on the eddy currents. If the current passing through the coil is an alternating current, then both the eddy currents and the force will change direction with the change in the current. The oscillating force causes the particles of the component to oscillate, generating an acoustic wave which then propagates through the component. For the EMAT to work, the component needs to be of electrically conducting material.

Hydro testing of pipes, pipelines and vessels is performed within our specially designed and constructed Hydro Bays, to expose defective materials that may have missed prior detection, to ensure that any remaining defects are insignificant enough to allow operation at design pressures, to expose possible leaks and to serve as a final validation of the integrity of the constructed system. ASME B31.3 requires this testing to ensure tightness and strength.

Buried high pressure oil and gas pipelines are tested for strength by pressurising them to at least 125% of their maximum allowable operating pressure (MAOP) at any point along their length.

Hydrostatic tests are conducted under the constraints of either the industry’s or the customer’s specifications or may be required by law.

Applications:

Pipeline Testing

As mentioned above, hydrostatic pressure testing within pipes and pipeline systems is crucial to many operations and projects.

Such tests ensure that – by using a specified test pressure – a pipe system is able to withstand the pressure from the other procedures being performed in the project. This provides peace of mind when it comes to the structural integrity and overall safety of various pipeline projects.

Pressure Vessel Testing

Just like with pipes, pressure vessels need to undergo a hydrostatic test to ensure they can hold their durability under various pressure levels.

Boilers, gas cylinders and fuel tanks are all examples of these pressure vessels – these pieces of equipment are used in various businesses and factories across a wide range of industries.

Benefits:

Testing that’s safer for workers

If the proper testing is not performed, there can be significant risk to not only neighbouring equipment, but to the operators of said equipment. Worker safety should be a top priority in any and all work environments – and reducing risks goes a long way to improving this safety.

Hydrostatic testing of pipe systems and small pressure vessels ensures that the equipment will be able to withstand the required pressure – allowing workers to operate said equipment without risk of failure.

A more preventative method that reduces time and costs

Hydrostatic testing is a reliable method for detecting even the smallest leaks that may not be visible during a visual inspection or other testing methods. By detecting potential weak spots or faults early, hydrostatic testing helps prevent catastrophic failures, reducing downtime, and maintenance costs.

On top of this, by ensuring the equipment is in optimal condition, hydrostatic testing can help to extend its operational lifespan. With a longer lifespan, maintenance and replacement costs will also be reduced.