logo GRT GAZGRT gaz - build the transport of tomorrow
Consulter le site Gas in Focus et la nouvelle édition 2017 - 2018
Le Gaz. L'Énergie des Possibles. - 10 new reports to discover
Activity and sustainble development report 2017
Launch of the appygas solution

Evaluating the risks of failure

When a potential flaw is detected in a pipeline, the best solution is often to cut the pipe and replace the faulty section. But what if it were possible to take a tiny sample of the steel to evaluate the actual risk? That is the goal of micro test samples.

Cutting principle proposed by Rolls-Royce; view of the machine in operation / Standard SENT test tube, and micro-test tube taken directly from the pipe in use
Cutting principle proposed by Rolls-Royce; view of the machine in operation / Standard SENT test tube, and micro-test tube taken directly from the pipe in use

Evaluating the risks of failure

During pipeline inspections, tools known as pipeline pigs are inserted into the gas flow in order to detect, measure and locate any type of potential flaw in the gas pipeline tubes. If it is unable to determine the steel’s actual mechanical characteristics, and thus evaluate the risks posed by this flaw, GRTgaz may opt to replace the potentially flawed pipeline section for security reasons.

To avoid this extreme solution, researchers have worked for years to find a correlation between the hardness measured on the pipeline surface (by perforation) and its mechanical characteristics. They compiled a database from measurements and observations collected on digs – without necessarily producing a reliable solution.

A reliable result, with no impact

A new strategy was adopted in early 2017: micro test samples were explored through a partnership with TOTAL and the Centre of Materials at Mines ParisTech. The process involves shaving a metal sample from the pipeline surface, with a controlled and limited impact to the pipeline’s integrity, while machining the sample to produce a “micro test sample” (flat piece of several millimetres, melded to a specific shape depending on the mechanical characteristic to test) used to test the steel’s traction, resilience and tenacity. In this way, the decision to replace a pipeline section is not taken by default, but only in case of actual risk.
Benefits of this method:

Cutting-edge equipment

Machining the micro test samples requires a high-precision tool made by only a few industrial companies like Rolls Royce.

In 2017, a feasibility study showed that the measurements obtained with a micro test sample are pertinent and correspond to the values obtained using standard test samples, which are much thicker and damage the pipe.

In 2018, research will continue to ensure that the values measured on the pipeline surface can reliable determine the steel’s mechanical characteristics throughout its full thickness.

To learn more