Long Range Pipe Screening
(Ultrasonics - Guided Waves)

This technique of nondestructive testing uses a low frequency ultrasonic guided wave that propagates along a pipe wall to examine long ranges of pipe very quickly. Often referred to as Long Range Ultrasonics (LRUT), it can be used to examine tens of metres of pipe in a single test. Access is only needed at the transducer position and the waves will propagate under insulation and other coatings.

LRUT can be performed on ferrous and non-ferrous alloys and on non-metallic materials, depending on their acoustic transmission capabilities.

LRUT is commonly performed on:

• Straight runs of pipe where 100% of the volume must be inspected
• Pipes covered with insulation or most kinds of coatings/wrappings
• Elevated pipework, even in tightly packed racks
• Pipes in sleeved road crossings
• Pipes with wall penetrations

LRUT is used to locate and identify:

• Wall loss
• Internal or external pitting and corrosion
• Axial or circumferential cracking
• Defects under various types of pipe supports

Sophisticated software routines help categorize reflections from changes in the cross section of the pipe. LRUT therefore gives 100% volumetric screening of up to 50m of pipe either side of the transducer ring location. The inspection can be performed on both gas and liquid filled pipes without taking them out of service and with minimal surface preparation. New application areas are continually being developed.

Access to the pipe is required to attach the transducer ring. Clearance of 3 inches around the pipe is required in the area of the transducer ring. Minimal surface preparation is necessary but the area must be free of any loose scale or paint. Pipe temperatures may be as high as 110C using fixed transducer rings and 70C for flexible transducer rings (higher temperatures can be tested by following specific precautions). Fast flowing product or high ambient noise will have an effect. Some coatings on pipes, such as a heavy bitumen, will affect the range/sensitivity.

NOTE: The system has been designed to operate as a screening tool that can quickly identify problem areas. When the pipe is accessible, it is frequently recommended that a detailed inspection (using complementary techniques) is performed at any identified defect areas.

The report is generated at the time of the test by the software. The processed results are presented as a trace that is similar to an A-scan in conventional ultrasonics. A cross-referenced schematic drawing of the piping allows for easy reference and repeatability of future inspections. The data file created is accessible at any time for additional analysis or reference. Test results are interpreted in accordance with current specifications and/or customer requirements.

Click here for some LRUT examples.