A 3D visualisation of Sonomatic's Stingray performing a pipeline inspection

Pipeline Inspection

The Fototerra Sonomatic JV delivers high-quality subsea pipeline inspection and integrity engineering services that provide operators with actionable data and insight. With decades of experience across global oil and gas infrastructure, we support clients through all stages of subsea inspection campaigns—from planning to execution.

We understand that pipelines are critical assets, and maintaining their integrity is essential to safe, efficient, and profitable operations. Failures or unplanned downtime can have severe financial, environmental, and safety consequences.

Our integrated approach combines campaign planning expertise, specialist tooling, and a comprehensive suite of advanced non-destructive testing (NDT) methods. These capabilities are supported by industry-leading statistical analysis techniques, delivering a more accurate and representative understanding of pipeline condition and remaining life.

By aligning inspection data with real-world asset performance, we help operators make informed decisions that extend asset life, reduce risk, and optimise long-term performance.

Quantitative Pipeline Assessments

The Fototerra Sonomatic JV has a long history of providing specialist quantitative subsea pipeline inspections on pipeline conditions, providing data that will offer the accuracies required that are suitable to use as part of the life extension study.

Inspection performance requirements, concerning the accuracy of measurement and Probability of Detection (POD), are key to ensuring a low coverage inspection provides a sufficient basis for statistical analysis of data.

A subsea image of an in-progress pipeline inspection
Advantages of Quantitative Assessments in inspection services:

Qualitative Pipeline Assessments

For pipelines, where ILI (In-Line Intelligent pigs) is considered too costly and a low coverage quantitative inspection does not provide suitable coverage to fulfil the requirements of a corrosion risk assessment, then qualitative inspection methods should be considered. Screening inspection is a less invasive method and typically provides for higher coverage; however, they typically provide a coarse percentage of wall loss at each location.

Screening techniques such as medium-range horizontally polarised guided shear waves, introduced by electromagnetic acoustic transducers (EMATs) and/or Multiskip, using shear wave pulse echo probes in a pitch/catch mode of operation, make screening of the pipeline possible and can provide a more global perspective of the pipeline.

An image of a Pipeline Inspection ROV being displayed
Advantages of Qualitative Assessments in inspection services:
  • Preferential weld root corrosion/erosion
  • Internal corrosion/erosion
  • Through coatings using SH-EMAT’s/multiskip techniques
  • Screening for pipelines
  • Probabilistic integrity assessments
  • Bespoke, ROV deployed magnetic crawling equipment
  • Does not require dredging of the pipeline
  • Identify areas of interest for follow up quantitative inspection

Pipeline Weld Inspection

The operating conditions and design of oil and gas pipelines may be such that it is susceptible to cracking in-service. Crack growth can be driven by cyclic loading (fatigue) or by the chemistry of the operating environment (stress corrosion cracking or environmentally assisted cracking). These damage mechanisms are more frequently encountered in welds but can also be present in the parent material.

Cracking can be a significant threat to the pipeline asset integrity, with the potential for catastrophic pipeline failure in the form of rupture, hence cracking mechanisms are a consideration in the integrity management of pipelines.

Pipeline inspection services play a vital role in providing and/or validating whether or not a cracking mechanism is present, the dimensions and locations of cracks present, the growth rate and distribution of growth rate for tracks and the characteristics of cracks, so that the mechanism can be understood.

The reliability of this information is fundamental to oil and gas pipeline integrity and operational decisions.

Pipeline Weld Inspection techniques and advantages include:
  • Automated shear wave pulse echo
  • Eddy current technologies
  • Time of Flight Diffraction (TOFD)
  • Consistent performance with minimised human factor effects
  • Substantially improved Probability of Detection (POD)
  • Improved sizing capability
  • Accurate positional control
  • Accurate position information for each scan
  • Full recording of all data for more detailed analysis
  • Reliable repeat comparisons

Oil & Gas Pipeline Inspection Services

Our pipeline inspection services help our clients meet increasingly stringent regulatory requirements and enhance the safety, productivity and life of their assets. Our technicians are highly trained and experienced in the latest pipeline inspection technologies, and our advanced data management capabilities ensure that all pipeline data is accurately captured and stored.

With our comprehensive pipeline inspection services, we can help our clients extend the life of their pipelines, improve safety and compliance, and boost productivity.

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Frequently Asked Questions

Automated corrosion mapping involves scanning the pipeline to determine the minimum remaining wall thickness for each position and can be achieved using an advanced automated ultrasonic tool. The systems deployed, produces comprehensive high-quality data that can be displayed in different views to easily identify and/or verify any areas of concern. Sonomatic Inspection Management Software (SIMS) is used to generate 2D and 3D thickness map composites to improve efficiency in data management during the collection phase, and assists in semi-autonomous data analysis and reporting.

Time of Flight Diffraction (TOFD) is a method of accurately sizing and monitoring the through-wall height of in-service flaws. It is effective for weld inspection flaw detection irrespective of the flaw type or orientation. TOFD doesn't rely on the reflectivity of the flaw but uses diffracted sound initiating from the flaw tips. TOFD's main advantage is that it has a through wall height accuracy of +/- 1 mm, and a crack growth monitoring capability of +/- 0.3 mm, on defects of all orientations.

Dynamic Response Spectroscopy (DRS™) is a proprietary technology developed by Sonomatic using frequency-based ultrasonic wall thickness measurements. It is a corrosion mapping technique that applies a broad range of low ultrasonic frequencies (<1 MHz) to penetrate challenging coatings such as composite repairs, PE and Neoprene, and excites the natural frequencies of vibration of the underlying steel. The DRS™ probe raster scans over an area of interest and collects response signals. Advanced signal processing algorithms have been developed to extract the vibration frequencies and map the wall thickness profile.

Pulsed Eddy Current (PEC) is a comparative technique whereby advanced processing of the eddy current signal decay and comparison with a reference signal, allows for the determination of the average wall thickness (AWT). This fast screening method allows for the assessment of the general condition of structural steel and is best suited for general corrosion type defects in subsea pipelines. A major benefit of PEC is its ability to inspect through concrete weight coating, challenging coatings and marine growth.

Angle shear wave methods are widely used in NDT and in most applications the probe is manually manipulated. There are, however, significant benefits to automating the process, both in terms of probe manipulation and data collection. The benefits include the following:

  • Consistent performance with minimised human factors effects
  • Substantially improved probability of detection (POD)
  • Improved sizing capability
  • Accurate positional control
  • Accurate position information for each scan
  • Full recording of all data for more detailed analysis
  • Reliable repeat comparisons

Automated shear wave pulse echo is used for a variety of applications, some  examples are listed below:

  • Inspection of welds to detect and size planar flaws.
  • Inspection of corrosion-resistant alloys for stress corrosion cracking.
  • Inspection of corrosion-resistant alloys for chloride pitting.
  • Inspection of materials in wet H2S service for vertical cracking elements.

EMAT technology is performed from top-of-line and has the capacity to detect internal and external corrosion on subsea pipelines with NWT <15 mm with coating thickness up to 4 mm. The technique does not require direct coupling as the input and received signals are generated by electromagnetic responses. This screening technique provides details of the lateral extent of corrosion with banding to indicate the through-wall severity level.

Multiskip is an ultrasonic rapid screening technique for corrosion and erosion detection on subsea pipelines ≥4” diameter. It uses two transducers mounted on wedges in a pitch-catch to send angled shear wave beams through the pipe wall by skipping multiple times off the ID and OD surfaces. The system is capable of high-speed, high-resolution data collection. For corrosion, loss of signal amplitude, reduction in signal arrival times, and changes to signal shape are used to provide qualitative and quantitative information.

Alternating Current Field Measurement (ACFM) is an electromagnetic technique for the detection and sizing of surface-breaking indications. It works on most metals, does not require direct contact and works through various thicknesses of coatings. ACFM can accurately detect and size linear indications both length and depth. It is also easier to use on complex geometries such as nodes and nozzles.

A phased array is a unique ultrasonic probe consisting of a group of transmitters or receivers, allowing for precise control of sound waves. When used as a transmitter, the timing of element activation creates interference that can shape and angle the beam. As a receiver, the time differences between pulse arrivals at each element provide information about the pulse source's location. Similar to how our ears work, phased arrays can pinpoint sound directions. Unlike traditional twin-crystal probes, phased arrays adjust signal phases for desired beam angles. However, their performance relies on the number, size, and spacing of elements, requiring specialised signal processing equipment. Phased arrays are widely used in radar, sonar, and medical applications but face challenges in NDT ultrasonics due to metal penetration and wave mode issues.

Ultrasonic testing utilises sound waves to detect corrosion within materials. This NDT technique utilises array transducers that pulse elements in a sequence called phasing.

Eddy Current Testing (ET) 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.

Project Examples

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