Pipelines and tanks provide a unique inspection problem as they often have vast areas to inspect for relatively small defects. Many conventional NDT methods are very good at detecting flaws in metals to very fine tolerances. However, they can be exceptionally time consuming to use, even when covering just one square metre.
Pipeline Inspections Using Innerspec Technology
Unlike these conventional NDT methods, Innerspec provide the perfect solution. The Innerspec range of equipment has fast screening capabilities to rapidly inspect large areas and pinpoint any areas of concern. The method used by Innerpsec is an ultrasonic testing (UT) method known as Electro-Magnetic Acoustic Transducer (EMAT). EMAT creates ultrasonic wave forms within a metallic material, guided by the inner and outer walls of a pipe or plate. EMAT uses the distinctive interaction between an energised coil and a permanent magnet, or a magnetised strip, creating ‘Lorentz Forces’ within the pipe material, which in turn generate guided ultrasonic waves.
These guided waves are in the form of shear waves or lamb waves. The lamb waves are further designated as symmetrical or asymmetrical, describing their wave propagation mode. By using guided and bulk waves we can detect flaws in materials up to 50m away from the search unit (coil) per inspection, without any couplant.
Using EMAT provides a range of other benefits including that we can inspect pipes containing product, inspect under lagging or insulation, detect corrosion under pipe supports and inspect pipes buried underground without expensive excavation.
The Volta is the most advanced of Innerspec’s portable instrument range. It boasts:
- 2-channel search units for ease of inspection interpretation.
- Advanced software generated filters.
- Software setup wizards and real-time online support.
- Superb reporting capabilities.
- Both Medium-Range and Long-Range Ultrasonic Testing (MRUT and LRUT) capabilities in the same instrument.
The LRUT Light package is an easy to set up, fast inspection tool that inspects up to 100m (50m in each direction) of pipeline in each shot. The shot takes mere seconds to capture, then the operator can annotate all the welded pipe joint indications on the A Scan followed by any other known features evident (valves, welded brackets etc.). Any A Scan signals that are not attributable to welds or features can be annotated as defects. This is a simple, fast exercise using a stylus and an Android tablet.
Once all the A Scan signals have been accounted for, the operator simply clicks the Distance Amplitude Correction (DAC) icon, and the software uses the weld signal amplitudes to produce a DAC Curve. Not only does it produce this curve, it also categorises all defects in 3 different adjustable colour bands and lists them accordingly along with their amplitude and axial dimension from a pre-recorded datum on the PDF report that the Volta software generates.
Our Technicians recently trialled the LRUT Light system on a fuel storage facility transfer pipe of approximately 220mm diameter, with a 100m inspection. Unlike many previous LRUT instruments, the dead zone was very small, at less than 0.5m while the sensitivity and axial resolution was outstanding.
Medium-Range Ultrasonic Testing Circumferential (MRUT-C) inspections utilise a 50mm wide strip of metallic tape adhered circumferentially around a pipe. This strip is then magnetised by swiping a bar magnet around the strip. The coil and its encoder are then rolled around the pipe over the top of the strip for one revolution. This method of EMAT produces shear waves within the pipe wall.
The shear waves travel axially along the pipe for approximately 3 metres in each direction and reflect signals back to the search coil from any changes in wall thickness, whether from welds, defects, or holes in the pipe.
This inspection provides excellent axial and circumferential resolution to pinpoint areas of concern. The MRUT-C is not a defect sizing tool; however, defects can be roughly estimated according to their signal amplitude.
This method is designed to detect flaws under insulation and lagging, underneath pipe supports, underground (up to 3m) or in any other inaccessible place. The Volta reporting software records all defects along with their amplitude, positions, and any notes the inspector wishes to make.
Medium Range UT Axial (MRUT-A) inspections are specifically designed for use on long runs of pipeline that would be far too time consuming or difficult, due to lack of access, to inspect with conventional UT. This method uses one (Pitch Catch) or two (Pulse Echo) search units on wheeled, handheld trolleys. The search units contain permanent magnets and the necessary coils for the application.
The search units only need the top surface of the pipeline (or any longitudinal surface) to inspect the full circumference. This makes it ideal for pipes ganged together, which creates limited access to the full circumference.
Once the unit is set up and adjusted correctly, the inspector can wear the Volta instrument on their back in the specially designed ergonomic ‘jetpack’. One hand controls the search unit handle and the other holds the Volta Android tablet. The inspector can then perform a walking speed inspection of the pipeline, detecting any change in wall thickness.
The axial position of any defect is immediately evident, then by twisting the search units 90 degrees and scanning circumferentially, the circumferential position of the defect can be quickly pinpointed and recorded. Each defect that is detected can be recorded both on the pipe itself and within the Volta software for reporting.
Once the entire pipeline has been scanned and all areas of concern recorded, conventional UT thickness measurement tools or Phased Array UT methods can be employed to inspect each pinpointed area and determine exact remaining wall thicknesses and map the corrosion or erosion precisely.
Like the other UT methods discussed, the inspections can be performed with or without product in the pipe and on pipes with concrete liners. Typically, any defect with 5% wall loss can be reliably detected at a slow walking pace and accurately located to within millimetres of a datum.
This method has proven to be exceptionally fast and cost effective for scanning many kilometres of pipe at a time.
Many of our clients find that the accuracy and approximate sizing of defects provided by both the LRUT and MRUT methods discussed above are sufficient to make sound engineering decisions regarding replacing sections of damaged pipe. This is without the added cost of following up with additional NDT methods to determine exact sizing of the defect. This, of course, is dependent on many factors and results are unique to each customer and application.
For a demonstration of any of the capabilities discussed, you can view the videos at the top of the page or view more demonstrations on our YouTube channel here. Our Brisbane office also has demonstration pipes available with a comprehensive array of typical defects and we would be delighted to demonstrate the equipment to you upon appointment. We are also very happy to bring the equipment to you to demonstrate its features and capabilities on your unique onsite applications.