Group to develop ultrasonic tools for detecting pipeline stress corrosion

An international group has formed a $5.3 million venture to develop ultrasonic tools for detecting stress corrosion in natural and liquid pipelines. The Gas Research Institute (GRI), British Gas plc, Canadian Energy Pipeline Association, and PRC International will adapt British Gas' elastic-wave vehicle pipeline inspection device to allow inspection of a wider range of gas transmission pipelines.

Dec. 16, 1996

2 min read

An international group has formed a $5.3 million venture to develop ultrasonic tools for detecting stress corrosion in natural and liquid pipelines.

The Gas Research Institute (GRI), British Gas plc, Canadian Energy Pipeline Association, and PRC International will adapt British Gas' elastic-wave vehicle pipeline inspection device to allow inspection of a wider range of gas transmission pipelines.

The device currently exists for only 30- and 36-in. lines. The partners will develop a device for 24-in. lines, which could be resized for pipelines of 20-30 in., and one for 42-in. lines, which can be resized for 32-48-in. lines.

The prototype devices will be designed and built in 1997-98 and field tested in 1998.

Ted Willke, GRI vice-president, said, "The commercial availability of emerging sensor technologies such as the elastic-wave measurement system will allow the industry to scrutinize a broader range of possible defects."

GRI said the British Gas elastic-wave vehicle was the first "smart pig" to use ultrasound technology to inspect pipelines for defects such as stress corrosion cracking.

It carries transducers inside liquid-filled wheels that roll along the inside surface of the pipeline. The liquid transmits the ultrasound from the transducers into the pipe wall, where it reflects off stress corrosion colonies and other longitudinal-oriented defects.

GRI said the new pigs would have gas bypass capability and the ability to negotiate tight radius pipe bends.

"In-line inspection devices operate at their best when traveling at less than 10 mph. In actual operation, however, natural gas normally flows through the line at much higher speeds and propels the smart pig along at speeds too high for optimum inspection.

"The new smart pigs will be able to control their speed relative to the gas stream velocity, and as a result, the line throughput will not be substantially reduced during inspection."

It said the smaller of the two vehicles will be able to traverse tight bends with a pipe bend radius as small as 1.5 pipe diameters.

"Tight radius bends are common in older pipelines, such as those in the U.S. with diameters 30 in. and less. It has been estimated that replacing these bends with larger radius bends would cost the industry more than $1 billion."