Indication
An indication is the response observed during an NDT examination that requires interpretation to determine whether it represents a relevant defect, a non-relevant geometric effect, or a false signal.
Definition
All NDT methods produce indications; the inspector must classify each as relevant, non-relevant (caused by part geometry such as a fillet weld), or false (caused by surface contamination, magnetic writing, or technique issues).
What it represents
Anything an NDT method makes visible or measurable that requires evaluation. An indication is not a defect: it is the raw observation, which evaluation then classifies as relevant, non-relevant or false.
How it is derived
The discipline is in the sequence — detect, interpret (relevant or not), evaluate (against acceptance criteria). Skipping the middle step is how geometry echoes become "cracks" in reports and how real flaws get dismissed as noise.
Where it is defined
The interpretation/evaluation sequence is written into ASME Section V and every acceptance standard; the vocabulary is defined in ASTM E1316.
How it is misread
Writing "defect" in a report where "indication" is meant. The words carry different contractual weight, and a report that calls everything a defect obliges responses the findings may not justify.
Where Indication fits in an inspection programme
A term is only useful when it connects to a decision. Indication appears in written procedures, in technique sheets, and in the records an owner or accreditation body reviews afterwards — which means the way it is defined in your documentation has to match the way it is applied on site. Where the two drift apart, audits find it. Atlantis writes and reviews procedures against the governing codes, trains inspection personnel to apply them, and builds the record-keeping that makes the evidence retrievable years later. Procedure development and code consulting · NDT training and certification · Ask us about your programme.
Related terms
- Relevant Indication — A relevant indication is an NDT response produced by an actual material discontinuity that must be evaluated against the applicable acceptance criteria for accept/reject disposition.
- False Indication — A false indication is an NDT response not caused by an actual material discontinuity, instead produced by contamination, technique error, magnetic writing, or instrument artifacts.
- Reference Reflector — A reference reflector is a machined feature in a calibration block — typically a side-drilled hole, flat-bottom hole, or notch — used as a known target to set instrument gain and build sizing curves.
More data terms
A-Scan · B-Scan · C-Scan · D-Scan · S-Scan · L-Scan · Distance-Amplitude Correction · Distance-Gain-Size · Time-Corrected Gain · Gating
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.