16.1 Inspection Stages, ITPs & Hold Points

16.1 Inspection Stages, ITPs & Hold Points

Quick Answer: Welding inspection is planned in stages—pre-weld, in-process, and final—using an Inspection and Test Plan (ITP) that assigns methods, acceptance references, and intervention levels (hold, witness, review/surveillance). Hold points block progress until authorised release; witness points expect attendance; review points check records; surveillance is planned sampling or oversight without necessarily stopping the line. IWI-S candidates must be able to read, review, and reason about ITPs, not only name the stages.

Quality fails when inspection is treated as a final walk-around. IIW/IAB Welding Inspection modules (including WI1.3 and WI1.6 themes) expect the Standard-level inspector to understand when work is checked, who must be present, and which documents justify release. This section is core Codes, Standards, Acceptance & QA Documentation material and feeds Application of Standards scenarios where a correct technical fact still fails if applied at the wrong stage.

Why Staged Inspection Exists

A completed weld that fails final NDT often represents wasted labour, consumables, and schedule—and sometimes a repair that is harder than the original joint. Staged inspection catches problems when they are still cheap:

1. Wrong material or preparation before welding starts
2. Parameter or sequence drift while the joint is open
3. Final acceptance evidence before handover

Each stage produces records. Those records become part of the dossier that proves the structure meets construction requirements years later. Oral examiners frequently ask: What would you check before welding this joint? and What would stop you from allowing the next pass?

Pre-Weld Inspection (Before the Arc)

Pre-weld inspection confirms that the work may start under the approved system. Typical checks include:

Pre-weld is where many hold points live: material release, fit-up acceptance, and first-use of a WPS on a critical joint are common examples. Starting without release is a process non-conformance even if the final weld looks perfect.

Exam trap: Knowing ISO 5817 limits does not excuse missing a pre-weld hold that required client or third-party release of fit-up.

In-Process Inspection (During Welding)

In-process inspection watches the joint while it can still be corrected economically. Typical activities:

• Verify preheat and interpass temperatures against WPS (thermometer/pyrometer method and location matter)
• Confirm layer sequence, bead placement, cleaning between runs, and absence of obvious surface imperfections that would trap slag or lack of fusion
• Spot-check parameters (current, voltage, travel speed/heat input where required) against WPS ranges
• Control repair of in-process defects under approved methods—not freehand “grinding until it looks fine”
• For multipass critical welds, intermediate visual or NDT stages may be ITP items before back-gouging is closed or before PWHT

In-process points may be hold (e.g., root pass VT/NDE before fill), witness (e.g., client watches first production joint of a day), or surveillance (periodic checks of parameters on a sample of welds).

IWI-S competence emphasises supervising Basic-level practice and verifying that production follows the WPS/WPQR framework—not performing every measurement yourself, but knowing what must be measured and recorded.

Final Inspection (After Completion / Before Acceptance)

Final inspection answers: Is this joint or item acceptable for the next stage (PWHT, coating, hydrotest, shipment, service)? Typical elements:

• Complete visual testing to the specified standard (e.g., ISO 17637 practice themes) and acceptance code (e.g., ISO 5817 level contracted)
• Execution and evaluation of NDT as required by the ITP (PT/MT/RT/UT, etc.) by personnel qualified under the project scheme (often ISO 9712 awareness)
• Dimensional checks of weld size, length, location, and residual distortion limits from drawings
• Confirmation that PWHT (if required) was performed and recorded, and that post-PWHT NDT was completed when specified
• Collation of as-built identity: welder IDs, WPS used, NDT reports, heat numbers, consumable batches

Final acceptance is often a hold for release to the next discipline or for client sign-off. “Looks good from the floor” is not a substitute for the ITP evidence package.

Inspection and Test Plan (ITP) Structure

An ITP (sometimes Inspection Test Plan / Quality Control Plan annex) is the sequence map of quality interventions. A usable ITP typically includes, for each line item:

1. Activity / stage description (e.g., “Fit-up VT of nozzle-to-shell weld joints”)
2. Reference documents (drawing numbers, WPS, specification clauses, acceptance standard)
3. Method (VT, dimensional, PT, MT, RT, UT, hardness, PMI, document review)
4. Frequency / extent (100%, 10% random, first of each welder/shift, each heat, etc.)
5. Acceptance criteria (code/level/tolerance)
6. Responsible party (fabricator QC, IWI/inspector, client, third party/notified body)
7. Intervention code (H / W / R / S — hold / witness / review / surveillance, or local equivalent)
8. Record form (checklist number, NDT report form, material release form)
9. Sign-off columns for the parties who must acknowledge completion

ITPs are living controlled documents. The inspector’s job includes checking that the ITP matches the construction specification and that shop practice matches the ITP—not inventing a personal inspection list that contradicts the contract.

Hold, Witness, Review & Surveillance

Distinguish intervention levels carefully—Application of Standards and oral questions love this vocabulary.

Who signs? The ITP defines signatories: fabricator QC, welding inspector (IWI or equivalent), client inspector, AI/third party, classification society surveyor, or regulatory body. Signatures mean that intervention was performed as coded—not a personal guarantee of lifetime fitness if other parties failed their duties. Never sign a blank line “for later.” Never sign a hold release you did not perform or for which acceptance criteria were not met.

Changing the ITP: Reclassifying a hold to a witness to “save schedule” is a controlled change. It requires authorised revision (document control, revision number, agreement of parties who own the hold—often client/engineering). Verbal “we’ll skip this one” is not control. If construction requirements change (e.g., NDT extent increases after a finding), the ITP and related procedures update together.

Linking Drawings, WPS & NDT to Stages

A professional ITP is not a generic template pasted onto every job. Linkages include:

• Drawings define joint locations, weld types, sizes, and sometimes NDT symbols or notes—inspection stages must cover all welds in scope, including temporary attachments if required to be removed and inspected
• WPS/WPQR define essential variables and any special examination after procedure qualification; production ITP stages verify those variables are respected
• NDT methods are timed: root NDT before fill; surface NDT after final surface is prepared; volumetric NDT after completion (and after PWHT when specified); film/report quality checks before acceptance of RT packages
• Material and consumable release usually sits early; final dossier review sits late

IWI-S vs Basic: At Standard level you are expected to develop or review QC plans/ITPs and to decide whether quality documents support construction requirements—not only to execute a checklist written by someone else.

Practical Inspector Workflow

1. Obtain latest drawings, specification, ITP, WPS list, and welder qualification matrix
2. Walk the pre-weld line items; clear holds before striking the arc
3. Sample in-process interventions per ITP frequency; escalate when trends appear
4. Complete final VT/NDT/dimensional package; resolve NCRs before release
5. File records so a later auditor can reconstruct who, what, when, to which criteria

Exam Focus

Expect questions that mix stage vocabulary with intervention codes: Fit-up is a hold; the client is not present—what do you do? Correct answer depends on ITP/contract, not personal urgency. Also expect scenarios linking a wrong WPS revision discovered at final inspection—the defect is organisational, and the corrective path includes NCR and possible re-inspection of already welded joints.

Master staged inspection and ITP language and you close the QA loop that Chapters 13–15 built with NDT and acceptance standards. The next section turns to material certificates and traceability—the evidence that the correct steel and consumables entered those stages.