Inspection and Test Plan, ITP.
An inspection and test plan, ITP is a quality document that lists, for a scope of work or a supplied item, every inspection and test activity in sequence, the acceptance criterion and reference procedure for each, the record it produces, and which party attends. It governs a supplier's manufacturing package or a construction scope, and it is the document hold points and witness points are written against.
What Inspection and Test Plan, ITP means.
An ITP is prepared by the party executing the scope, a supplier building an instrument package or a contractor installing it, and submitted to the purchaser for approval before work starts. Each row is one inspection or test activity in sequence, with the acceptance criterion, the reference procedure, the record it produces, and an intervention point marking who must attend, witness, or review afterward. A supplier ITP typically runs from material certification through calibration, pressure test, and factory acceptance test to release for shipment. A construction ITP runs from mounting and tubing through cable termination, insulation and continuity checks, calibration check, and loop check to handover. Because it is executed per tag, its records tie into the instrument index and feed mechanical completion and the handover dossier. It fails when a hold point is signed without the required party present, or records are not keyed to a tag.
What an ITP is and what it covers
An inspection and test plan is a quality-assurance document, not a test procedure. It does not tell an inspector how to perform a hydrostatic test or how to calibrate a transmitter; it lists the sequence of inspection and test activities a scope of work or a supplied item must pass through, from the first receiving inspection to the final release, and against what it is checked. A single ITP can cover one purchased item, such as a transmitter or a control panel, or an entire construction scope, such as the instrumentation for one process unit. Most projects require a separate ITP for each major scope or package rather than one document covering the whole facility, because the activities, the standards referenced, and the parties who attend differ by discipline and by supplier.
The intervention point codes
Every ITP row carries an intervention point that states what each party must do at that activity. The codes vary by project and by client standard, but the same four categories recur. A hold point stops work entirely until the specified party has attended and signed off; the activity cannot proceed past that point without that signature. A witness point invites the party to attend, but work may continue on a notified schedule if the party does not show up, since the intent is opportunity to observe rather than a mandatory stop. A review or surveillance point is satisfied by inspecting the record after the fact rather than attending in person. A monitor point is a lighter version of the same idea, a periodic check on a recurring activity rather than a one-time attendance. Because the codes are not standardized across the industry, an ITP always defines its own legend, and the same letter or abbreviation can mean different things on two different project specifications.
The supplier ITP on a purchased instrument or panel
An instrument engineer meets an ITP in two places. The first is a purchased instrument or a panel, where the supplier submits its own ITP as part of the technical bid or the purchase order. A typical supplier ITP for a transmitter or a panel runs through incoming material certification, in-process checks, calibration against a certified reference, a hydrostatic or pneumatic pressure test where the item is pressure-retaining, a factory acceptance test that exercises the item against its functional specification, a final visual and dimensional inspection, and release for shipment. The purchaser's inspector attends the calibration and the factory acceptance test as hold or witness points on most specifications, and reviews the material certificates and the final inspection report without attending in person.
The construction ITP for field installation
The second place is the construction ITP for field installation of the same instrument once it reaches site. Its activities typically run mounting and support installation, impulse line or tubing routing and pressure test, cable installation and termination, continuity and insulation resistance checks on the cable, a calibration check against the datasheet range, a loop check that confirms the signal reaches the control system and reads correctly, and handover of the completed loop to commissioning. The construction ITP references the same tag the supplier ITP was written against, but its activities and its hold and witness points belong to the installation contractor's quality plan, not the manufacturer's. Where a project runs both a supplier ITP and a construction ITP for the same instrument, the two documents cover different activities on the same tag and neither replaces the other.
How the ITP ties to the record, and where it goes wrong
An ITP row is executed and signed against a specific tag, and that record is what lets the instrument index and the loop check plan pull together a complete history for a single loop rather than a pile of certificates in no particular order. A completed construction ITP, together with the loop check, is one of the records mechanical completion is declared against, and both feed the handover dossier the operating company receives at the end of the project. Four failure modes recur. A hold point is signed by someone who was not actually present, so the record asserts an attendance that never happened. The acceptance criterion on a row points at a specification revision that has since been superseded, so the check was made against the wrong reference. Records are kept by activity or by date rather than keyed to a tag number, so nobody can assemble the ITP history for one loop without searching multiple files. And a supplier ITP and a construction ITP both claim the same calibration record, so the instrument appears to have been calibrated once when the two documents describe two different calibration events.
ITP columns
The fields most inspection and test plans carry, whatever the project's own template calls them.
| Column | What it carries |
|---|---|
| Item or activity | The inspection or test step, in the order it is carried out |
| Reference standard or procedure | The code, specification, or internal procedure the activity is checked against |
| Acceptance criterion | The pass condition for the activity, stated directly or by reference to the specification |
| Intervention point | Hold, witness, review or surveillance, or monitor, naming which party is involved |
| Responsible party | Who performs or attends the activity, for example supplier QC, purchaser inspector, or third party |
| Record generated | The document the activity produces: a certificate, a test report, a check sheet |
| Tag or item reference | The instrument or equipment identifier the row is executed against |
| Sign-off | Signature and date confirming the activity is closed |
Intervention point types
The four categories used across most projects, though the exact codes and their letters are set by each project's own specification.
| Intervention point | What it requires |
|---|---|
| Hold point | Work stops until the named party attends and signs off; the activity cannot proceed without that signature |
| Witness point | The named party is notified and may attend; the activity proceeds on the notified schedule if they do not |
| Review or surveillance | The party checks the record after the activity rather than attending it in person |
| Monitor | A periodic or spot check on a recurring activity rather than attendance at a single event |
Common questions
What does an ITP contain.
What is the difference between a hold point and a witness point.
Who prepares an ITP.
How does an ITP differ from a loop check plan and a punch list.
How are ITP records keyed to tags.
What happens at mechanical completion.
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