There’s no such thing as adding inspection later.
An Inspection and Test Plan isn’t a formality attached to the purchase order. It’s the one document that has to exist before the first cut — because most of what it controls cannot be added back in once the steel is closed, heat-treated or painted.
The purchase order specified “10% radiography.” Nobody wrote down which joints, or at what stage. The fabricator tested the seams that were easiest to reach, after the vessel had already gone through post-weld heat treatment. When the client’s engineer later asked for radiography on two nozzle-to-shell welds — the joints actually driven by the service conditions — the vessel had been stress-relieved and painted. Reopening that area meant undoing finished work to re-test it. The percentage on the purchase order was met. The point of the inspection wasn’t.
This is what happens when an inspection scope lives as a single line on a purchase order, instead of as a document of its own, agreed before fabrication starts.
What an ITP actually is
An Inspection and Test Plan is a document — agreed between the manufacturer, the client and, where applicable, the Notified Body, before the first cut — that specifies, for every characteristic that has to be verified, which operation it belongs to, what is checked, against which acceptance criteria, by which method, by whom, and whether that step is a hold point, a witness point or a review point. It is a schedule with inspection built into it, not a checklist attached at the end.
Hold, witness, review — the three words that decide who waits for whom
Hold pointWork cannot proceed past this point without the specified party’s presence and sign-off. Miss it, and the fabricator stops.
Witness pointThe specified party has the right to attend. If they don’t show up after proper notice, work proceeds without them.
Review pointNo physical presence is required at all. The specified party reviews the finished record afterward.
Get these three labels wrong in either direction and something breaks. Mark a witness point as a hold point, and the schedule waits on someone who never intended to be on site that day. Mark a hold point as a witness point, and the client loses a right they thought they had — discovering it only once the vessel is already closed.
What belongs in the plan, item by item
What a real ITP specifies for every characteristic
- The manufacturing stage or operation — material receipt, forming, welding, heat treatment, NDT, pressure test, final inspection
- The specific characteristic being verified — a dimension, a weld’s visual condition, radiographic quality, hardness, surface finish
- Acceptance criteria and the code or standard it’s measured against
- Method and the procedure reference that governs it
- Who performs it — the fabricator’s own QC, a subcontractor, the client, the Notified Body
- Hold, witness or review classification, and who holds that role
- The record the step produces, and where it lives in the final dossier
Why it has to exist before the first cut
Most of what an ITP controls is irreversible in one direction. A weld buried under a second pass can’t be re-inspected without grinding it back out. A microstructure changed by heat treatment can’t be un-changed to redo a hardness test under different conditions. A joint under insulation or paint has to be exposed again before it can be examined at all. None of that is expensive because inspection itself is expensive. It’s expensive because it means undoing finished work to get back to a point that should have been checked before the work moved on.
Mark a hold point as a witness point, and the client loses a right they thought they had — discovering it only once the vessel is already closed.
Who actually writes it
An ITP is not a document the fabricator writes alone and hands over for signature. The applicable PED conformity assessment module sets where the Notified Body has to be involved — described in the first article in this series. The client’s own technical specification sets requirements beyond the code. And the certificate type required for each item — 3.1 or 3.2, covered in the second article — belongs in the plan as a specific line, not a general note. The ITP is where those three inputs actually meet, before any of them becomes a surprise during fabrication.
How we handle it
The ITP is drafted before material is ordered, not after fabrication starts — built from the category, the module, the client specification and the certificate requirements together, in one pass.
Every point has a named owner. Hold, witness and review points are assigned to a specific party, not left as a general “client may attend” note that nobody actually schedules against.
The plan stays live. It’s referenced during production as work progresses, not filed away once as a compliance artifact and forgotten until the final review.
Three questions about your next ITP
- Has hold, witness and review been explicitly assigned for every party with a stake — or is it left for the fabricator to interpret?
- Which steps become impossible, or far more disruptive, once heat treatment, painting or insulation happens — and are they scheduled before that point?
- Does the plan name the certificate type and NDT method for each item, or does it just say “per code”?
Planning a pressure equipment project?
Send us the drawings and your inspection requirements. You’ll get back a draft ITP — hold points, witness points and certificate types assigned — before the first cut.
