Contact Coupling
Contact coupling is the ultrasonic technique in which the probe is pressed directly against the test surface with a thin film of couplant between them; the simplest and most common UT setup.
Definition
In contact coupling the probe is hand-held against the test surface, with a thin layer of couplant bridging the air gap. Most field UT is performed this way.
Related terms
- Couplant — A couplant is a liquid or gel (water, glycerin, propylene glycol, or proprietary gel) applied between the ultrasonic probe and the test surface to transmit sound energy by eliminating the air gap.
- Immersion Testing (Immersion UT) — Immersion ultrasonic testing places the probe and test piece in a water tank; water provides constant coupling and enables precise focused-beam scanning of complex geometries, common in aerospace and tube manufacturing.
- Ultrasonic Testing (UT) — Ultrasonic Testing (UT) is an NDT method that uses high-frequency sound waves (typically 0.5–25 MHz) to detect internal flaws and measure thickness in metals, plastics, and composites by analyzing reflected echoes from a transducer.
More procedure terms
Source-to-Film Distance · Exposure Chart · Wet Particle Method · Dry Particle Method · Fluorescent Particles · Visible Particles · Demagnetization · Multi-Directional Magnetization · Solvent-Removable Penetrant · Water-Washable Penetrant
Where this comes up in practice
Terms like this one appear in three places that matter commercially: the written practice that governs how your personnel are qualified, the procedures and technique sheets that define how an examination is actually performed, and the evidence an auditor or client asks for when they want to know why an inspection was accepted. Getting the terminology right is the easy part; being able to produce the qualification record, the calibration traceability and the procedure revision that applied on the day of the inspection is the part that decides audits.
Atlantis NDT provides NDT training and certification against ASNT SNT-TC-1A and ISO 9712, ASNT Level III consulting for written practices and procedure approval, inspection management software that holds qualification, calibration and procedure-revision evidence in recoverable form, and an asset integrity platform that binds inspection results to the asset they describe. Browse the full NDT glossary or ask a Level III directly.