Image Quality Indicator (IQI)

An image quality indicator (IQI), also called a penetrameter, is a device placed on the source side of a radiographic test piece to verify image sensitivity and resolution by displaying known features such as wires or holes.

Definition

An IQI is a calibrated device of known thickness, wire diameters, or hole dimensions placed on the part being radiographed. The smallest visible IQI feature establishes the demonstrated sensitivity of the radiograph. Two main styles are used worldwide: wire IQIs per ISO/EN and hole-type IQIs per ASTM/ASME.

When It Is Used

Every radiograph requires an IQI as required by ASME Section V, API 1104, and ISO 17636.

Related terms

  • Wire IQI — A wire IQI is a set of parallel wires of progressively decreasing diameter encased in a clear plastic envelope, used per ISO/EN standards to verify radiographic sensitivity.
  • Hole-Type IQI — A hole-type IQI is a thin plaque with three drilled holes of diameters 1T, 2T, and 4T (where T is the plaque thickness), used per ASTM/ASME standards to demonstrate radiographic sensitivity.
  • Radiographic Sensitivity — Radiographic sensitivity is the smallest detail or thickness change reliably detectable in a radiograph, demonstrated by which IQI feature is visible — for example, 2-2T hole IQI or wire #10 wire IQI sensitivity.
  • ASME Section V — ASME Section V (Nondestructive Examination) is the chapter of the ASME Boiler and Pressure Vessel Code that defines NDT methods, procedures, and personnel qualification requirements for examinations referenced by other ASME construction and in-service codes.

More equipment terms

Calibration Block · Transducer · Dual-Element Probe · Angle-Beam Probe · Normal-Beam Probe · Couplant · Reference Reflector · Side-Drilled Hole · Flat-Bottom Hole · Notch Reference

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.