Advanced Nondestructive Examination (NDE) - Development and Advancements

The development of advanced NDE techniques/tools is one of the reasons the inspection trade has taken significant steps forward in the last couple decades; and the advancements appear to be accelerating.  One of the many ways to keep up with advancing NDE technology is to attend the semi-annual NDE task group meetings at the Spring and Fall API Refining and Equipment Standards Meetings.  In fact, that T/G is planning to document many of the advanced NDE techniques in a new API RP 586⁽¹⁾. Work on the document is just getting underway, so it may take a few years before anything is published. I anticipate that sections will be published piecemeal so as not to delay the usefulness of the document for owner-users until all of the current advanced NDE methods are recorded; and when that happens, I suspect the RP will be well in excess of 100 pages. In the meantime, below is a partial list of one-liners describing some of the advanced NDE technology in use or being developed for the petroleum and petrochemical industry.

On one end of the advanced NDE spectrum are techniques/tools that are in widespread use and generally available; while on the other end of that spectrum, others are still being developed or showing some promise, but have seen very little use so far.  Some will only detect damage, while others can characterize the damage and size it.  Some are screening techniques for finding areas of possible damage and “roughly sizing” it, while others can provide highly accurate data detailing the extent of damage.  Some advanced NDE techniques combine an assembly of probes using multiple sensors/transducers. Most of the widely used, standard NDE techniques are not in this list of advanced techniques (e.g. PT, MT, EC, RT, etc.).  Some of these techniques have been available for decades, while others are still being developed. A few of them include (click on any of the topics to view their individual pages on Inspectioneering):

• Acoustic Emission (AET) – A technique for detecting transient elastic waves in a material undergoing localized cracking or corrosion.
• Automated Ultrasonic Backscatter Technique (AUBT) – A collection of ultrasonic techniques for detecting HTHA in equipment that is documented in API RP 941.
• Computer Aided Radiography (CAR) – Computer based image processing tools for enhancement and manipulation of RTR images to improve resolution and focus on areas of interest in a digital radiograph.
• Eddy Current Array (ECA) – A technique that drives multiple eddy current coils placed together in the same probe assembly for flaw detection and sizing of surface cracks.
• Infrared Thermography (IR) – A nonintrusive, noncontact system for mapping thermal patterns on the surface of an object using infrared detectors.
• In-Line Inspection (ILI) – The inspection of pipe and pipelines using “smart pigs” (both tethered and non-tethered) that use primarily UT/MFL for detection and sizing of damage.
• Internal Rotating Inspection System (IRIS) – An ultrasonic technique for detecting and sizing corrosion in pipe and tubing using an internally inserted probe that generates sound waves.
• Laser Scanning of Coke Drums – A profilemetry technique for creating a profile of in-service coke drum deformation sometimes combined with other advanced NDE techniques such as video and ultrasonics.
• Long Range Ultrasonic Testing (LRUT) – a technique that uses low frequency guided wave ultrasonics (GWUT) for detection of internal and/or external corrosion (CUI) in pipe and tubing.  
• Magnetic Flux Leakage (MFL) – a technique that is used to detect corrosion in steel piping and storage tanks whereby a magnetic detector that is placed between the poles of the magnet detect a leakage field where corrosion is present.
• Meandering Winding Magnetometer Array (MWMA) – A relatively new technique for detecting and characterizing corrosion and cracking using multiple inductive sensors.
• Phased Array Ultrasonic Technique (PAUT) – a set of UT probes made up of multiple small elements each of which is pulsed individually with computer-calculated timing which can be used to inspect more complex geometries that are difficult and much slower to inspect with single probes.
• Pulsed Eddy Current (PEC) – A technique for measuring wall thicknesses on insulated equipment without having to remove the insulation and jacketing.
• Real Time Radiography (RTR) – A radiographic technique that produces an almost immediate electronic digital image of the item being inspected/ radiated rather than on film.
• Remote Field Eddy Current (RFEC) – An electromagnetic technique for finding defects in piping and tubing using an internally inserted probe that generates a magnetic field.
• Remote Visual Inspection (RVI) – refers to methods of enhanced visual examination means of visual aids including video borescopes, push cameras, pan/tilt/zoom cameras and robotic crawlers.

When you have an unusual or difficult inspection issue that may require advanced NDE techniques, the services of a capable, qualified NDE SME are highly advisable and generally cost effective.  Many of these more advanced NDE techniques are somewhat “black box” technologies, not easily or readily understood by plant engineers and inspectors whose primary inspection and FEMI duties are much broader-based than just advanced NDE. NDE SMEs can help determine which technique(s) to use, when to use multiple techniques, what the real advantages and limitations of each technique are, which NDE service companies and technicians are best qualified to do the work, which NDE service companies have the best equipment, and if the NDE procedures that are offered are applicable or appropriate for the specialized NDE work.

Are you making cost effective use of advanced NDE to solve difficult or unusual inspection problems that otherwise might result in equipment failure and a process safety incident?

This article originally appeared in the 101 Essential Elements in a Pressure Equipment Integrity Management Program. The entire guide is available for download now.