Quantitative Acoustic Emission Non-Destructive Inspection (QAE NDI) is a full diagnostic non-destructive method for on-line inspection, assessment and long-term monitoring programs of critical piping systems, equipment and structures.
QAE NDI is based on a physical phenomenon of acoustic emission (stress wave emission). Scientifically defined, acoustic emission is a phenomenon of sound and ultrasound wave generation by materials that undergo deformation and fracture processes. Sources generating AE in different materials are unique. For examples, in metals, primary macroscopic sources are crack jumps, processes related to plastic deformation development and fracturing and de-bonding of inclusions. Quantitative and qualitative characteristics of acoustic emission waves, generated by sources of different nature depend directly on material properties and environmental factors.
Leaks, friction and impacts are other examples of sources generating acoustic emission waves. These sources belong to another, secondary class of acoustic emission that is usually distinguished from the primary class of sources related to deformation and fracture development. Interpretation of the nature of emitted sound, characteristics of sounds and what they represent, is be used for development of practical technological solutions for inspection and assessment of critical equipment and structures.
QAE NDI diagnostic capabilities
Unlike traditional AE testing method that is limited normally to detection and location of AE sources, QAE NDI was developed as a full diagnostic method that is also capable of identifying flaw indications and assessing them in known fracture mechanics parameters such as stress intensity factor or J-integral. Ability to provide diagnostic information is crucial for proper decision making, superior detectability and minimizing false position and false negative results.
Particularly, QAE NDI provides:
- Overall inspection of the piping/equipment during normal operational conditions, covering 100% of the line ID, OD, circumference, length and volume of the metal and provides a color coded risk map of the line.
- Accurate detection, location and identification of QAE indications of various types of micro- and macro- cracks that have J-integral value equal to or greater than 0.03JIc.
- Revealing and assessing of QAE indications related to thermal and mechanical fatigue, creep damage development at pre-micro-cracking and micro-cracking stages, systems of fracturing and de-bonding inclusions, local material embrittlement, pre-fabricated weld defects and other.
- Detecting and identifying QAE indications of mechanical impacts and their origin, malfunctioning of hangers and supports, statically and dynamically overstressed zones, leaks, malfunctioning valves, areas subjected to thermal shocks, etc.
- Valuable information for predictive and preventive maintenance.
Diagnostic capabilities are based on the learning process that is done in five areas for every single QAE NDI application: fracture mechanics rejection criteria, failure mechanisms, material properties, AE method, structural design and operational conditions.
QAE NDI structural health monitoring capabilities
QAE NDI applied on running piping or equipment, under real operational and stress conditions. This allows us to apply QAE NDI as a structural health monitoring system that is capable of the following:
- Identify operational conditions causing flaw accumulation and development.
- Identify hangers' problems.
- Water and steam hammering events.
- Thermal shocks.
- Identify gate, control and safety valves issues and leaks.
- Detect flow turbulences and fluctuations and their effect on structural integrity of piping.
- Reveal effectiveness of repair.
QAE NDI proven experience and smoking gun case studies
After hundreds of projects and many years of practical application, QAE NDI has demonstrated its maturity, reliability and accuracy. Numerous documented double blind, confirmation and verification tests have demonstrated excellent detectability, accurate assessment and agreement with other NDE methods. There were several cases when QAE NDI predicted and warned about impending failure while other NDE method could not detect the problem.