Pigging the unpiggable

APTS’ services have established a reputation of excellence across oil, gas, construction and mining sectors.

In order to keep up with technologies in the industry and to extend its offerings and capabilities, APTS has entered a strategic alliance with Netherlands-based Intero Integrity Services BV – a specialist provider of inspection services for unpiggable pipelines. The alliance allows APTS to provide the resources and equipment to undertake ultrasonic pigging inspections of pipelines throughout Australia and New Zealand.

Intelligent pig inspection systems are important tools to manage the integrity of pipelines, enabling operators to assess the failure risk due to metal loss corrosion, using the findings of the survey; however, not all pipelines can be inspected this way.

Unpiggable pipelines

Not all pipelines were designed to carry out inspection services. There may be several reasons why the pipeline cannot be pigged, including no launch/receiving facilities, varying diameters or bends, making conventional pigging techniques impossible.

Although industry standards and policies have changed over the years, with uptime being precious and replacement piping being increasingly expensive, inline inspection (ILI) has been a valuable service.

Versatile pigging tool

Intero has developed the Piglet®, a versatile inspection tool on a mobile platform for use anywhere in the world at any time. The device uses ultrasound technology to examine the condition of the pipeline.

The tool is equipped with an ultrasonic measuring head, containing one ultrasonic transducer (sensor) and a rotating mirror.
The measuring head transmits ultrasound and receives the inner and outer pipe wall reflections.

In addition to the visualisation of the ultrasonic signal itself, the data acquisition unit translates the signal into the following four outputs, which are presented online:

  • wall thickness (t)
  • distance of centre of pipe to inner wall (IR)
  • signal amplitude of the inner wall reflection
  • signal amplitude of the outer wall reflection.

Real world experience

APTS and Intero were recently contracted by a diversified chemicals manufacturer to carry out ILI and hydro testing on an 8 inch (203 mm) sulphuric acid pipeline at the Port of Townsville, Queensland.

Piglet was used to inspect the pipeline, with the above outputs providing a complete picture of the condition of the pipe wall, as well as all necessary information to detect and quantify features and anomalies in the pipeline. Extensive analysis of the raw data determined the remaining wall thickness and further enhancement of reliability was achieved using multiple outer wall reflections.

Advanced algorithms determined the validity and reliability of each measurement.

During calibration of the ultrasonic measuring head, the parameter ‘offset trigger delay’ was determined in order to compensate for the distance between the ultrasonic transducer and the mirror. The inner radius then accurately quantified the geometric information of the pipeline, such as dents and ovalities.

Resolution

The proposed resolution of the inspection was based on a 100 per cent coverage of the pipe wall for an inspection surface area of 10 by 10 mm. A higher resolution would have been possible with the rotating mirror inspection Piglet, offering up to 300 per cent coverage of the pipe wall on an area of 3.3 by 3.3 mm.

Following the inspection, a hydrostatic test was conducted on the pipeline before the project was successfully completed. The collaboration between APTS and Intero on the project reinforces the benefits of the alliance, specifically the knowledge and resource sharing between the businesses.

This article was featured in the July edition of The Australian Pipeliner. To view the magazine on your PC, Mac, tablet, or mobile device, click here.

For more information visit the APTS website.

If you have a project you would like featured in The Australian Pipeliner contact Managing Editor David Convery at dconvery@gs-press.com.au

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