Small diameter tube and pipe inspection poses a particular set of challenges. A few difficulties inspectors face include limited access between pipes, the thinness of the pipe or tube wall, and the sheer number of required inspections. Historically, radiography has been the perferred method for this application, since scanner mechanics and relatively large sensor sizes excluded advanced ultrasonics from consideration. Now, however, ultrasonic phased array technology offers a fast, readily viable option for small diameter pipe and tube inspection. By using phased array, you can avoid all the inherent difficulties and disadvantages that accompany radiographic inspection, such as safety, speed, and regulatory issues, as well as the need to clear the inspection area.
The Olympus COBRA Solution, based on a COBRA scanner and accessories kit coupled with an OmniScan portable phased array flaw detector, is specifically designed to address small diameter inspections. The COBRA Solution kit is a complete scanning solution for the inspection of pipes and tubes ranging from 0.84 in. to 4.50 in. OD (21 mm to 114 mm). For the inspection of pipes and tubes situated in close proximity, the COBRA scanner operates within a 12 mm (0.5 in.) clearance. The scanner adheres to the pipe or tube by a spring mechanism, which permits 360-degree scanning, even when only one side of the pipe or tube is accessible. The spring mechanism also enables the COBRA to adhere to non-ferromagnetic materials. The versatile COBRA scanner has the capacity to simultaneously inspect from both sides of a weld, or it can be adapted to be used with a single phased array probe for welds with one-sided access, such as elbow and pipe-to-component welds.
The complete COBRA Solution portable kit provides you with all the necessary tools, including setup templates, probes, curved wedges, and all other accessories required to inspect throughout the usable range. The kit can be purchased as a complete or single probe system, depending on your needs. The COBRA Solution is a semiautomatic system that complies with ASME as well as other inspection codes requiring full data collection and encoding, including those addressing the use of ultrasonics in lieu of radiography.
To even further improve small diameter phased array inspections, the COBRA Solution features probes that have been specially designed for this particular application. Phased array probes can be electronically focused in the forward or active axis by controlling the pulse and reception of the elements. Without complex array construction (dual/matrix array, etc.), the passive axis has long been left to natural beam spread, which is determined by aperture and element dimensions and the frequency of the probe. CCEV (Concave Curvature in Elevation) probes were created by applying a curvature in the elevation axis (also known as the side-to-side, or passive axis) dimension of a phased array probe. The appropriate curvature was established through laboratory trials and beam simulations for the typical diameters and wall thicknesses of both pipeline construction welds and small diameter pipe and tube welds. Similar to applying a lens to an immersion probe, the result is a smaller beam spot width, which can lessen beam spread effects and increase length-sizing potential. An internal integrated lens allows the use of standard flat wedges and flat outside casing. Various probe frequencies and wedges (refracted longitudinal and sheer) are available to address different materials, such as austenitic pipe or tube. TOFD compatible ultrasonic wedges and probes are also available.
*Note: Longitudinal and TOFD wedges increase the required clearance needed for inspection.