Symbiotic Approach: Spiral Welded Pipe Inspection with Two Advanced Technologies

Application Note By: Andrew Simpson - Technical Sales and Applications Engineer

Source: Symbiotic Approach: Spiral Welded Pipe Inspection with Two Advanced Technologies (eddyfi.com)

The strength of spiral welded pipelines is typically higher than straight seam welded piping, and they are commonly found in the energy, construction, and other industrial sectors. You may spot spiral welded pipes serving as load-bearing columns used in bridges and infrastructure requiring protection against wind and earthquakes or integrated anywhere from upstream to downstream installations. Although strong, these pipelines aren’t impervious to external factors that can impact their structural integrity. What may appear fine from the outside may tell a different story elsewhere. For example, internal corrosion is encouraged when pipe contents contain H2O, CO2, or H2S gases – typical of gas pipelines. Stress specifically located at the spiral weld combined with corrosion is a recipe for disaster and standing by for an external crack to reveal the truth isn’t worth the wait. We present the multi-technology Beyond Current solution that enables reliable risk management.

As with any introduction of new inspection technology, it is important to validate performance in a controlled environment. This introduction required the procurement of a spiral welded sample with artificially manufactured corrosion defects. A combination of the Silverwing Pipescan HDTM and R-Scan Array systems were put to the test to demonstrate the benefit of using a combined solution to maximize productivity and provide quantitative results of damaged areas. The Pipescan HD was used to rapidly screen the majority of pipe walls and identify areas with a pre-determined reporting threshold, 30% material loss in this case. The R-Scan Array was then used to measure the depth of indications. Where physical restrictions with dead zones or areas where neither tool could be used —approximately 100mm (4in) on either side of the spiral weld— manual scanning was performed using a G3 zero degree wedge and Phased Array (PA) probe for both detection and characterization of defects. The sample was 16mm (0.6in) nominal wall thickness. Although the Pipescan HD works on a range of thicknesses, as with all NDT methods, there are optimal conditions for performance. To balance detectability with ergonomic performance, the magnetic strength was designed to saturate 12.7mm (0.5in) wall thickness to detect wall thinning as discreet as 10%. It should be noted that thicker material can also be inspected but the defect would need to be larger for detection. With this in consideration, it emphasizes the benefits of using a supplementary technology such as Phased Array. This combination of advanced techniques resulted in a highly efficient inspection with precise data collected in particular areas, increasing productivity while maintaining a high PoD. Check out the results for yourself!

Pipe Sample Details

• Material: Carbon Steel
• Nominal Thickness: 16.0mm/0.6in
• Outer Diameter: 915mm/36in
• 6 artificial defects drilled internally at different depths

• 4 linear scans (185mm/7.3in wide) performed from left side to diagonal weld using Pipescan HD
  
• 17 vertical scans (60mm/2.4in wide) performed also from left diagonal weld using R-Scan Array
• Areas adjacent to the welds were scanned with near wall coverage PA probes

Figure 1: Pipe Sample with Defect Locations

Equipment Used

• MFL Pipescan HD scanning head PS-HD-MFL-127XFLAT and  data acquisition unit
• PAUT R-Scan Array manual encoded system and M2M  acquisition unit
• G3 64element 7.5MHz probe and L0-G3 wedge