Ultrasonic NDT: A quick, safe, and proven solution for ensuring piping system integrity


GF Piping Systems has developed the first ultrasonic NDT solution for plastic pipelines. The new solution is an important part of a comprehensive quality management strategy during pipeline construction and installation.

Piping system integrity is crucial for owners and operators of water, gas, and industrial plants. Demonstratively, 1 in 300 welds fail every year due to poor construction. 

It costs around AU$1.5 million to repair a leak in a gas pipeline, and a single failure could jeopardise the entire system, as, on average, one initial problem results in 19 incidents. From installation to putting a project into operation, the uncertainty of the system’s operational performance is a significant stressor for project supervisors, as leaks in a newly installed system can have a serious impact on the economic performance and image of their organization or business. 

Assessing a system’s condition, particularly by using ultrasonic non-destructive testing, can alleviate these concerns.

Ensuring piping integrity

It is essential that piping systems are safe and long-lasting. Assessing your system’s condition allows you to anticipate any damage your system is susceptible to and can help with planning maintenance.

A combination of two methods allows for worry-free operation: ultrasonic non-destructive testing (NDT) provides analysis at the installation stage, while pipe condition can be assessed during operation to estimate the remaining lifespan, plan maintenance and repair work, avoid failures, and minimise revenue loss. 

Gaining this information means that operators can make informed decisions when installing, operating and maintaining their system, while managing any dangers, too.

Solving problems through innovation

When installing a system, the welds are critical. They are often considered to be the weakest points but are essential for safe and reliable operation.

Until recently, assessing the quality of welds in piping systems was impossible without destroying them. Project supervisors were forced to replace welds that were potentially still in good condition or risk system failure. 

Conventional pressure tests cannot provide any information on the system’s long-term performance, whereas destructive tests are not able to ascertain the quality of any untested welds. 

Ultrasonic NDT provides scientific evidence to assure operators that welds are safe. Developed by GF Piping Systems, the first ultrasonic NDT solution for plastic pipelines is part of a comprehensive quality management strategy. 

The technology provides a pass or fail grade and works on all materials (HDPE 100, RC, PP, etc.) and fusion types (butt weld, electrofusion, infrared, etc.). It uses ultrasonic waves to detect possible defects in a material and a weld assessment algorithm that identifies indications of weakness in the welds and extrapolates this information into an evolution of the weld’s strength over the long term within seconds.

The process for ultrasonic NDT is as follows:

Inspectors visit the construction site and assess the piping system’s welds for any indication of weakness using various ultrasonic testing methods (TOFD, PAUT, etc.) and advanced, patented equipment.

If they detect any signs of weakness, they identify and measure them before recording the information in a report. The report then feeds in to the assessment algorithm, which gives a pass or fail grade.

If the welds are approved, trenches can be resealed and no further action taken.

There are many advantages to ultrasonic NDT:

  • The assessment algorithm at its heart ensures total objectivity
  • Improves quality and safety.
  • Contributes to increased efficiency and reduced costs.
  • Helps extend the lifespan of piping systems.
  • Cost efficiency, guaranteed

In a recent pipeline project in Papeete, Tahiti, Geocean used the GF Piping Systems Specialised Solutions ultrasonic NDT service and welding machines during the installation of an underwater sea water air conditioning (SWAC) piping system for the General Hospital of French Polynesia. 

The Polynesian government commissioned the SWAC with the aim of advancing energy transition and benefiting from the reduced costs that result from lower energy consumption. SWAC is a solution to the problem of energy-intensive cooling systems, providing air conditioning to nearby buildings using cold water from the depths of the ocean. 

The principle is simple: the first pipe pumps sea water at 5°C into the hospital air conditioning system. Once used, the water is then discharged back into the ocean at a temperature of around 12°C.

The hospital’s SWAC is the longest of its kind globally and involved the installation of two pipelines: a 3800 m-long intake pipeline reaching a maximum depth of 900 m and a 200 m-long discharge pipeline. The pipelines comprised of several NPS 710 mm HDPE pipes welded together through polyfusion. 

The ultrasonic NDT checked the 400 welds were completely sealed, providing an immediate pass or fail grade and a full report available within 24 hours. 

Polyethylene pipes are flexible and mould around their environment on the seabed, thereby creating areas of tension on the pipe walls. These can cause weak points around the welds in the fused material. Ultrasonic NDT is the best way to guarantee the same level of efficiency in welds as in the rest of the pipes throughout the system’s lifespan, as it can be used prior to installation and operation and without needing to send random welds to a laboratory or conduct pressure tests, which would result in costly repairs. 

In other words, thanks to ultrasonic NDT, weld quality can be guaranteed immediately from installation.

The SWAC has helped the Polynesian government reduce electricity consumption by 12 GWh, creating an annual saving of 5000 metric tonnes of CO2 and $4.26 million in hospital energy costs. Ultrasonic NDT contributed to these energy savings by ensuring the pipelines were completely sealed, thereby maximising the system’s air conditioning capacity. 

For more information visit www.gfps.com/au.

This article is featured in the September edition of The Australian Pipeliner. 

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