16.2 Developing and Approving NDT Procedures

16.2 Developing and Approving NDT Procedures

Quick Answer: Domain 5.2–5.4 (with Domain 2.5–2.6) expects Level IIIs to develop NDT procedures and work instructions, validate techniques, and approve internal and supplier procedures. A procedure is not a narrative essay—it is a controlled document tied to governing requirements, with defined essential variables, calibration, evaluation steps, acceptance references, and records. Writing without demonstration is incomplete when codes or customers require procedure qualification.

Section 16.1 taught you to read requirements. This section is how you turn that matrix into executable, approvable work instructions that technicians can follow and auditors can verify.

Why Procedure Ownership Sits with the Level III

Method-level certification does not automatically mean a Level II may author the controlling procedure. Under typical employer programs and many product codes:

• The NDT Level III develops, reviews, and/or approves procedures for methods in their technical responsibility.
• Level II personnel may provide technical input and perform examinations to approved procedures.
• Level I personnel work under direct guidance using procedures/work instructions within defined limits.

Basic exam items often ask who approves the procedure, who qualifies the technique, or what happens when a parameter changes. Anchor answers in Level III technical ownership unless the scenario explicitly assigns another authority (for example a customer Level III for supplier approval).

What a Complete NDT Procedure Should Contain

Exact section titles vary by company and method standard, but a defensible procedure usually addresses:

1. Document control — number, revision, date, approver(s), distribution, superseded revisions.
2. Scope — method, techniques, product forms, thickness ranges, materials, weld types, manufacturing stage.
3. References — invoked codes, standards, specifications, drawings, acceptance documents, personnel Written Practice.
4. Personnel — required certification level/method (and technique limits if any); vision currency as applicable.
5. Safety and environment — radiation safety interface, chemicals, magnetic fields, confined space coordination (as applicable)—without replacing the site safety program.
6. Equipment and materials — instruments, transducers/probes, films/detectors, magnetizing equipment, penetrant materials families, lighting, reference standards.
7. Calibration and system checks — what is checked, how often, acceptance of the check, reference blocks, DAC/TCG or densitometer checks as applicable.
8. Surface preparation and access — cleanliness, coating limits, temperature windows, geometry constraints.
9. Examination technique — setup, coverage, scan plans, angles, magnetization direction, dwell times, exposure geometry, etc.
10. Evaluation of indications — relevant vs non-relevant reasoning, sizing method, comparison to acceptance criteria reference.
11. Acceptance criteria — either embedded (if authorized) or clearly pointed to the governing document; never left as “shop judgment” only.
12. Reporting and records — required fields, unique IDs, image/film identification, retention, nonconformance routing.
13. Repair and re-examination — when required after blend, weld repair, or rework.

Work instructions or technique sheets then narrow scope for a part family or job, always under the parent procedure’s control.

Developing Procedures from Requirements (Not from Memory Alone)

A strong development workflow:

1. Extract the requirements matrix (16.1).
2. Select method/technique capable of finding expected discontinuity types at the required stage (Domain 2 method selection logic).
3. Draft the procedure against method standards and shop capability.
4. Identify essential variables (see below).
5. Validate/qualify the technique where required (demonstration on representative specimens, IQI/sensitivity checks, known defects, or code-required demonstrations).
6. Approve and release under document control.
7. Train affected personnel and update certification technique lists if the Written Practice requires technique-specific qualification.
8. Monitor field use and revise when nonconformances or process changes appear.

Internal vs supplier procedures

Approving a supplier procedure is not a rubber stamp. If the supplier’s technique cannot meet sensitivity or coverage, your product still fails when the nonconformance appears later.

Essential Variables: The Control Concept

Essential variables are parameters that, if changed beyond allowed limits, can materially affect the examination’s ability to detect or evaluate discontinuities. The concept appears across welding procedure qualification and NDT procedure thinking; Basic expects you to reason about it even when a specific code table is not quoted.

Examples of parameters often treated as essential or tightly controlled (method-dependent):

• UT: probe frequency/angle/size family, instrument type class, calibration block design, scan plan coverage, couplant class if it affects response, evaluation level method.
• RT: energy/kV range or isotope, source-to-film/detector distance geometry class, film/system class, IQI type/placement rules, density/SNR windows.
• PT: penetrant system family (visible/fluorescent; water-washable/post-emulsifiable/solvent-removable), dwell bands, emulsifier parameters, developer type, UV-A intensity/ambient light limits.
• MT: magnetization method (yoke/prod/coil/bench), current type, field direction relative to expected flaws, particle vehicle, lighting, field strength verification method.
• ET: frequency, coil type/configuration, fill factor/geometry assumptions, calibration standards, phase/amplitude evaluation settings.
• VT: lighting levels, direct vs remote aids, magnification limits, acceptance aids (gauges).

Why essential variables matter on the exam

• Changing an essential variable without revision can invalidate the qualified procedure.
• Non-essential variables may be adjusted within documented ranges without full re-qualification.
• Auditors ask: “Show me that what was done on the floor matches the approved parameters.”

Exam trap: Treating every convenience change (different brand of the same class of material, within validated range) as automatically requiring a full new procedure—or the opposite extreme of changing frequency, technique family, or acceptance path with no control.

Technique Validation and Procedure Qualification

Developing a procedure on paper is necessary but not always sufficient. Validation (sometimes called procedure qualification, technique demonstration, or performance demonstration depending on the industry) shows that under the stated conditions the technique can detect the discontinuities of interest at the required sensitivity.

Typical validation evidence (industry-dependent):

• Calibration and sensitivity demonstrations on code-required blocks or IQIs
• Trials on representative welds/parts with known artificial or natural discontinuities
• Blind or open trials when customer specifications demand them
• First-article examination with customer witness when the ITP requires it
• Periodic re-validation when equipment families or processes change

Domain 2.5–2.6 language about developing procedures and applying methods ties directly here: the Level III selects a method and proves the selected technique is fit for purpose.

Approval criteria checklist

Before signing approval, the Level III should confirm:

• Scope matches the jobs that will use it
• References include the correct editions and acceptance documents
• Personnel requirements align with the Written Practice and customer invocations
• Essential variables are identified and controlled
• Calibration/system performance is measurable and recorded
• Evaluation and acceptance paths are unambiguous
• Forms/reports capture traceability fields
• Any required demonstration package is complete and archived

Reject or return for revision when acceptance is “use good judgment,” when equipment is undefined, or when the procedure cannot be followed as written on real shop parts.

High-Yield Exam Traps for This Section

• Approving procedures that conflict with invoked specs “because production is behind.”
• Confusing document approval with personnel certification of the technician.
• Believing a Level II practical exam alone replaces procedure qualification for a new technique family.
• Changing essential technique parameters mid-job without revision/re-validation.
• Approving supplier procedures based only on a logo and a generic quality certificate, with no technical review.
• Writing procedures that omit acceptance reference or record requirements.

If you can draft a procedure outline, list essential variables for a named method, describe how you would demonstrate sensitivity, and explain when a parameter change forces re-approval, you have the Domain 5.2–5.4 / 2.5–2.6 spine the Basic exam targets.