CRI IQI Selection & Radiographic Sensitivity 2 — Questions and Answers
Question 1: What is the primary purpose of including an IQI in a radiographic setup?
- To verify the radiographic technique provides adequate sensitivity to detect discontinuities (Correct answer)
- To directly measure the dimensions of discontinuities found in the weld
- To calibrate the output of the X-ray generator or isotope source
- To determine the optimum film density for the exposure
Correct answer: To verify the radiographic technique provides adequate sensitivity to detect discontinuities
The IQI demonstrates that the radiographic technique is sensitive enough to detect discontinuities of a specified minimum size within the material being examined.
Question 2: Which type of IQI is most commonly specified in ASME Boiler and Pressure Vessel Code Section V for weld radiography?
- Hole-type (plaque) IQI (Correct answer)
- Wire-type IQI
- Step-wedge comparison IQI
- Micro-dot IQI
Correct answer: Hole-type (plaque) IQI
ASME Section V Article 2 primarily specifies hole-type (plaque) IQIs for pressure vessel and piping weld radiography, though wire IQIs are an alternative.
Question 3: When multiple film placements are used to radiograph a circumferential weld, what is the minimum IQI requirement per placement?
- One IQI per individual film placement (Correct answer)
- One IQI for the entire circumferential weld
- Two IQIs per film placement, on opposite ends
- One IQI for every three consecutive film placements
Correct answer: One IQI per individual film placement
Each film placement requires at least one IQI to confirm that the radiographic technique meets sensitivity requirements at that specific location.
Question 4: When source-side IQI placement is impractical, and film-side placement is used instead, what must the radiographer do?
- Place an 'F' designator on the IQI and document it in the radiographic report (Correct answer)
- Double the number of IQIs used to compensate for reduced sensitivity
- Increase the radiation dose by 50% to account for the placement change
- Switch from a hole-type to a wire-type IQI
Correct answer: Place an 'F' designator on the IQI and document it in the radiographic report
An 'F' (film-side) marker is placed on or adjacent to the IQI, and the deviation must be noted in the examination report per code requirements.
Question 5: What is the 'essential hole' on a hole-type IQI?
- The smallest-diameter hole that must be visibly discernible on the radiograph to satisfy code sensitivity requirements (Correct answer)
- The largest hole on the IQI used as a gross reference
- The center mounting hole used to attach the IQI to the test object
- A reference hole used exclusively for equipment calibration purposes
Correct answer: The smallest-diameter hole that must be visibly discernible on the radiograph to satisfy code sensitivity requirements
The essential hole is the minimum required visibility standard; if this hole is clearly visible, the radiographic technique meets the specified sensitivity level.
Question 6: How is radiographic sensitivity expressed as a percentage calculated using a hole-type IQI?
- (IQI thickness ÷ specimen thickness) × 100 (Correct answer)
- (Specimen thickness ÷ IQI thickness) × 100
- (Visible hole diameter ÷ specimen thickness) × 100
- (Source size ÷ source-to-film distance) × 100
Correct answer: (IQI thickness ÷ specimen thickness) × 100
Percent sensitivity equals IQI thickness divided by the specimen thickness, multiplied by 100, expressing the minimum detectable thickness variation as a fraction of the total.
Question 7: Which of the following factors does NOT directly determine the IQI designation number selected from code tables?
- Source-to-film distance (SFD) (Correct answer)
- Nominal material thickness being radiographed
- Whether a single-wall or double-wall technique is employed
- The material type of the test object
Correct answer: Source-to-film distance (SFD)
SFD influences geometric unsharpness and exposure time but is not a variable in IQI selection tables, which are driven by material thickness, technique type, and material group.
CRI IQI Selection & Radiographic Sensitivity 2
What is the primary purpose of including an IQI in a radiographic setup?