Why an ITP is more than “a QA document”
For heavy weldments, the real cost is rarely the inspection itself. The cost comes from late discovery, unclear acceptance criteria, and missing evidence during customer review. An Inspection and Test Plan (ITP) prevents that by turning requirements into a controlled sequence of checks, records, and decision points that align with how the weldment is actually produced.
Well-built ITPs also map directly to management-system expectations around controlled production and documented information. ISO guidance on “documented information” explains the intent: organizations choose the right amount of documentation to demonstrate effective planning, operation, and control of processes. (ISO)
1) What OEMs typically want from an ITP
An OEM-ready ITP answers three questions quickly:
1.1 What is checked, and when?
The plan must mirror the fabrication flow, from incoming material to final release.
1.2 Who is responsible, and what is the acceptance criteria?
Each checkpoint needs:
- responsible party (fabricator, customer, third-party)
- method (visual, dimensional, NDT, document review)
- acceptance criteria (drawing tolerances, WPS, execution class rules, NDT acceptance level)
1.3 What evidence will be delivered?
The ITP should generate a clear “evidence pack” that is ready for customer acceptance, not a pile of disconnected files.
2) The ITP backbone: checkpoints, hold points, and records
A practical ITP for heavy weldments uses three control types:
- Hold Point (H): work stops until the hold is released by the defined authority
- Witness Point (W): customer/third-party may attend; work may continue if they do not attend within the agreed time window
- Review Point (R): document review, no physical stop, but evidence must be available
This approach is widely used because it balances control and throughput. It is also consistent with how welding quality systems treat inspection and verification as integrated steps, not end-of-line activities. (ISO)
3) Practical ITP template for heavy weldments
Below is a template you can adapt to most welded assemblies. The goal is to keep it lean, auditable, and aligned with risk.
3.1 Contract and technical review (R)
Purpose: confirm requirements are understood and feasible before cutting starts.
Typical checks and records
- drawing and specification review checklist
- weld map and joint list
- WPS list (with revision control) and welder/robot cell qualification coverage
- inspection scope definition (visual, dimensional, NDT, coatings)
This stage prevents “inspection surprises” later, especially when requirements are implied rather than explicitly listed.
3.2 Incoming material control (W/R)
Purpose: ensure materials and certificates match requirements.
Typical checks and records
- material identification and traceability link (heat/batch to work order)
- certificate pack capture (as required by contract)
- receiving inspection results
If structural tolerances and acceptance are involved, it can be useful to align the plan with recognized tolerance frameworks used in steel fabrication practice. SteelConstruction.info highlights how tolerance practice in structural steel fabrication often references EN 1090-2 and, where appropriate, ISO 13920. (media.sbi.se)
3.3 Cutting, preparation, and fit-up (W)
Purpose: prevent misalignment and geometric drift from the start.
Typical checks and records
- edge preparation verification (bevel angle, root face, cleanliness)
- fit-up measurements for critical joints
- tack weld controls (tack size and spacing, sequence guidance)
3.4 Pre-weld verification (H for critical weldments)
Purpose: lock the joint condition before heat input makes correction expensive.
Typical checks and records
- WPS confirmation for joint and position
- preheat and interpass controls where applicable
- fixture and datum verification for acceptance-critical interfaces
This is the most common missing hold point in heavy fabrication. Adding it for critical interfaces reduces downstream rework significantly.
3.5 In-process welding controls (W/R)
Purpose: ensure the process is stable, not only the outcome.
Typical checks and records
- parameter window compliance (manual or automated recording approach)
- weld sequence adherence for distortion-sensitive seams
- in-process visual checks and defect containment actions
Quality frameworks for fusion welding emphasize that inspection and testing should occur before, during, and after welding, with records supporting control and improvement. (ISO)
3.6 NDT and acceptance mapping (W/H depending on severity)
Purpose: detect internal and surface discontinuities at the right time.
Typical checks and records
- NDT method and extent per weld class or contract (VT, MT, PT, UT, RT)
- acceptance criteria reference (contract standard, execution class requirements, customer rules)
- reporting format and traceability to weld IDs
If you work under EN 1090-2 execution, welding inspection classes (WIC) and inspection selection guidance are often used to define what is inspected and at what rigor, including the link between execution class and acceptance approach. (media.sbi.se)
3.7 Dimensional verification and geometry release (H for critical interfaces)
Purpose: confirm geometry before final finishing, coatings, or shipment.
Typical checks and records
- measurement plan for acceptance-critical dimensions (datums, interfaces, hole patterns)
- measurement records linked to part ID
- controlled correction process (if required)
This checkpoint is where many OEM acceptance delays are won or lost. If the dimensional record is incomplete or not tied to a stable part ID, the evidence pack is weakened.
3.8 Surface preparation, coating, and final inspection (W/R)
Purpose: ensure finishing does not obscure identification or invalidate acceptance.
Typical checks and records
- surface prep verification (if contract requires)
- coating checks (where applicable)
- final visual and packaging inspection
- identification legibility check after paint or finishing
3.9 Final dossier and release (H)
Purpose: deliver an acceptance-ready evidence pack.
Typical contents
- material certificate references (as required)
- WPS list and revision status
- NDT reports mapped to weld IDs
- dimensional inspection record
- NCR and repair history, if any, with closure evidence
- delivery checklist
4) Common reasons OEMs reject an ITP, and how to avoid them
4.1 The ITP is not aligned with the real build sequence
If checkpoints do not match production reality, operators bypass them and records become inconsistent.
4.2 Acceptance criteria are vague
Use explicit references: drawing tolerances, execution class rules, contract NDT acceptance, defined inspection class logic. (media.sbi.se)
4.3 Records exist, but are not linked
Traceability is not just “having reports.” It is linking each report to the part ID, weld ID, and revision status, which is aligned with the broader intent of controlled documented information. (ISO)
4.4 Hold points are missing where risk is highest
Add hold points at:
- pre-weld verification for critical joints
- geometry release before finishing
- final dossier release before shipment
Next steps
If you are preparing an RFQ or supplier qualification for heavy weldments, an OEM-accepted ITP is one of the fastest ways to reduce acceptance delays and limit rework risk. SL Industries can support with ITP structuring aligned to fabrication flow, acceptance-critical measurement checkpoints, and a clean documentation package ready for customer review.
Contact SL Industries at +359 (82) 841345 or info@sl-industries.com.
Sources (selected)
- ISO guidance on “Documented Information” in ISO 9001:2015. (ISO)
- ISO Online Browsing Platform: ISO 3834 series overview (quality requirements for fusion welding). (ISO)
- DNV overview of ISO 3834 certification and quality requirement levels. (DNV)
- SteelConstruction.info: fabrication accuracy and tolerance practice referencing EN 1090-2 and ISO 13920 usage. (media.sbi.se)
- EN 1090-2 weld inspection and WIC guidance (presentation referencing Annex L concepts). (media.sbi.se)
