Pipeline Inspection

Sonomatic has a long history of providing specialist inspections that deliver quality data on pipeline conditions. Our approach is to provide data and analysis that maximises the value of the inspection to the client. We can deliver our pipeline inspection services both topside and subsea.

Pipelines are key assets for operator companies and continued pipeline integrity underlies successful business performance. They are essential to oil and gas production and failures or unplanned downtime can have a major impact on company revenues. Failures can also have severe pipeline safety and/or environmental damage consequences.

Sonomatic assists operators by providing a range of pipeline inspections and integrity services including innovative statistical analysis methods that ensure decision making is aligned to the real condition of pipelines. These methods offer a significantly more representative view of pipeline condition and remaining life than traditional methods of data analysis and application of inspection data in pipeline inspection integrity assessments.

The application of Sonomatic’s analysis methods leads to major benefits for oil and gas pipeline operators.

Quantitative Pipeline Assessments

Sonomatic 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.

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.

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

Sonomatic 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.

Frequently Asked Questions

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 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. 

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.

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.

Eddy Current NDT is used to measure the intensity of electrical currents in a magnetic field.

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