How to write an ITP that works in practice

The ITP, or inspection and test plan, is the backbone of quality control in a fabrication project. It records, per process step, which inspection or test takes place, against which criterion, by whom, and which party must be involved. A well written ITP prevents inspections being missed, clients being unpleasantly surprised and end of project arguments about what was and was not checked.

In practice we see two extremes: the ITP copied from a previous project as a box ticking exercise and then filed away, and the ITP so detailed that nobody works with it. This article describes how to produce one in between: complete enough to steer the project, practical enough for daily use.

What an ITP is, and what it is not

The ITP is a table that follows the fabrication sequence, from material receipt through to final inspection and documentation. Each line contains an activity and its verification: the inspection or test, the reference procedure or standard, the acceptance criterion, the record to be produced and the involvement of each party.

The ITP is not a quality plan. The quality control plan (QCP) describes the organisation, responsibilities and working methods for the whole project; the ITP is the concrete inspection schedule that follows from it. The two documents should reference each other. We cover the difference in our article on the quality control plan.

Structure: the columns you need as a minimum

A workable ITP has at least these columns per line:

• Sequence number and description of the activity, in fabrication order.
• Reference document: drawing, WPS, procedure or standard, for example EN ISO 15614-1 for procedure qualification or ISO 17637 for visual testing.
• Acceptance criterion, for example ISO 5817 level B or the tolerances of EN 1090-2.
• Verifying record: which report, certificate or log constitutes the evidence.
• One column per party (manufacturer, client, third party or notified body) showing the type of involvement.

Number the lines logically per phase: material, preparation, fit up, welding, NDT, post treatment, testing, coating, final inspection, documentation. That links the ITP directly to the schedule.

Hold, witness and review points

The heart of the ITP is the set of intervention points per party. The usual classification:

• Hold point (H): production must not proceed until the designated party has inspected or released. Proceeding without release is a non conformity.
• Witness point (W): the party is invited to attend. If they do not appear within the agreed notice period, production may continue.
• Review (R): the party reviews documents afterwards, such as reports and certificates.
• Surveillance or monitor (S or M): sample based oversight without a fixed stop.

Use hold points sparingly: each one is a planned standstill. Place them where verification is impossible later, such as checking joint preparation and fit up before closing welds, or a pressure test.

Assigning responsibilities clearly

Every ITP line has an owner. Record who performs the check, who writes the report and who signs the release. For welding related items, the role of the welding coordinator under ISO 14731 should be recognisable: who reviews the WPS, who monitors welder qualifications to ISO 9606-1, who releases welds.

Do not forget the external parties. For pressure equipment under PED 2014/68/EU the notified body has its own mandatory intervention points; copy these into the ITP verbatim. Where an independent inspector acts for the client, record which points they attend and how they are notified. Filling that role independently is exactly what our QA and QC support service is set up for.

Client agreement: before the start, not after

An ITP is only valid once all parties have approved it. Send the draft to the client and any third parties early, incorporate their intervention points and record the approved revision before fabrication starts. Also agree the practicalities: the notification period for witness and hold points (five working days is common), how invitations are issued and what happens if a party does not attend.

Then keep the ITP alive. If the fabrication sequence changes or a process step is added, revise the ITP with visible change marking. An ITP that no longer matches reality is itself a finding at any audit or handover.

Common mistakes when writing an ITP

These mistakes come up most often:

• Copying from an old project without updating references and criteria to the new contract.
• Leaving acceptance criteria vague: a check is listed, but not the level it is assessed against.
• No link to the verifying record, so at handover nobody knows which report belongs to which line.
• Too many hold points, so the schedule stalls and parties quietly start skipping them.
• Not updating the ITP after changes, so dossier and reality drift apart.

If you link signed off ITP lines directly to the dossier build up, there is hardly any tracing work left at the end of the project. Our article on the MRB and MDR explains how to set that up.