Winner of the 2007 Global Pipeline award presented by the American Society of Mechanical Engineers International Pipeline Technology Institute, the Porcupine detects and defines longitudinal defects including channelling corrosion, erosion, preferential longitudinal weld line and general wall thinning, as well as typical pitting corrosion and small inner diameter (ID) corrosion.

The magnetic flux leakage (MFL) technique using longitudinal induced flux fields does not do well on the sizing definition of longitudinally oriented corrosion or on defects that create general wall thinning.

MFL technology is also limited by wall thickness especially above 19 mm. In MFL pigs of 14 inches or below, the limitation of internal area for magnets intensifies the problems created by wall thickness. As production goes deeper, the wall thickness of pipelines generally increases so that the use of MFL in some systems has a limited application.

Ultrasonic (UT) technology requires a homogeneous liquid to fill the pipeline, reducing its application on most production pipelines and all gas pipelines. A second limitation of UT is that pipelines inspected by that method need to be very clean to avoid false or no signal return.

The Porcupine’s direct measurement of the internal surface and its discontinuities avoids these limitations. The sensor fingers measure axial movement in both directions from its calibrated set point at the nominal inner diameter (ID) of the system being inspected. The range of motion of the sensor is accurate to 0.004 inches. The sensor finger range also allows the accurate measurement of almost any wall thickness.

In comparisons to UT pig results and to external C-Scan UT inspection, the correlation has proved the tool’s performance and resolution to be similar in both normally formed corrosion and longitudinal channelling corrosion.

Porcupine’s direct measuring technique is also very tolerant of soft or movable debris in the pipeline allowing for inspections in lines that are resistant to cleaning such as those containing paraffin. Debris that is not movable such as scale or other hard deposits will be detected and measured as to the area covered and the thickness of the deposits. This information allows the evaluation of pipeline cleaning programs and their modification based on data from the Porcupine.

Scale deposits that may hide corrosion or corrosion colonies can also be defined as to thickness, area covered and location. Operators can then decide the best method for eliminating the areas of scale, allowing chemical or mitigation treatments to reach the affected areas.

Another benefit of the Porcupine technology is the tool’s flexible design. The tool has been proven in dual diameter pipelines and in bend radius down to 1D in some sizes. This will allow some systems now considered unpiggable to be pigged with the technology.

The technology has now been used in pigs up to 42 inches and is now being adapted down to 3 inches. Proof of the technology in field applications and comparison of the technology to both MFL and UT techniques have proven this system is now ready to be applied to any pipeline system.

The high resolution response and the high degree of flexibility also make this technology applicable to other areas where the technology will answer integrity questions about high value assets. Some of these asset classes are heat exchangers, like steam generation systems and coker refinery units. PipeWay is currently developing the Porcupine technology for tube inspection for the applications.

The inspection of tubes in these heat exchanger systems will be able to detect and define defects such as small diameter corrosion, erosion, and general wall thinning and bulging. The detection and definition of the defects will be for both the straight pipe and the numerous elbows in the system.

An added benefit of this inspection is that it will be able to check for remaining scale, therefore determining whether the tubes are clean prior to putting the units back in service.

The Porcupine technology offers a unique, flexible and accurate method to inspect pipeline and tubed systems for required defect and cleanliness information to make integrity and asset management decisions.