Factory acceptance test (FAT): procedure, checklist and sign-off

A factory acceptance test (FAT) is a structured test of equipment — a skid, control panel, packaging line, switchgear, a machine built to order — carried out at the manufacturer's premises before shipment, usually with the buyer present. Its purpose is simple: find the problems while the equipment is still next to the people who built it, rather than on site where every fix costs travel, downtime and schedule. A factory acceptance test is only as useful as the procedure behind it, agreed in advance and executed line by line.

What a factory acceptance test procedure includes

• Scope: the equipment, serial numbers, drawings and specification revision being tested.
• Prerequisites: calibrated instruments, utilities available, software version frozen, documents on hand.
• Visual and dimensional checks: build quality, labelling, wiring, welds and conformity to drawings.
• Functional tests: start-up, sequences, interlocks, alarms and emergency stops, run under simulated conditions.
• Performance tests: capacity, speed, pressure or accuracy against the contractual values.
• Acceptance criteria for every step, with space for measured results.
• A punch list for deviations and a signature block for the manufacturer and the buyer.

Factory acceptance test vs site acceptance test

The FAT and the site acceptance test (SAT) are two halves of the same process, often written together as "FAT and SAT". The FAT checks the equipment in isolation at the factory, where simulated inputs replace the real plant. The SAT repeats the critical tests after installation, connected to real utilities, real process conditions and the systems it has to integrate with. Passing the FAT does not remove the need for an SAT; it reduces how much can go wrong during it. Reuse the FAT procedure as the basis for the SAT so the results can be compared line for line.

Do not accept "we tested it internally" in place of a witnessed FAT on critical equipment. The value of the test is that the buyer sees the failures and agrees the fixes before the equipment is crated.

How to run the FAT on the day

1. Circulate the FAT procedure for approval weeks in advance, with the same test references used in your inspection and test plan.
2. Confirm prerequisites the day before: instruments calibrated, software version recorded, drawings at the right revision.
3. Execute each step in order, recording the measured result, pass or fail, and who witnessed it.
4. Log every deviation on the punch list with a category — must fix before shipment, fix on site, or accepted as is.
5. Raise a non-conformance report for failures that affect the specification, not just cosmetic items.
6. Sign the FAT report with the punch list attached; release for shipment only when the must-fix items are closed.

Ettex Records keeps the test and the punch list in one place: one row per FAT step with result, witness and photos, and a linked table of punch items with owner, category and closure date. The same structure carries over to the SAT, so the site team starts with the open items from the factory instead of a blank sheet. When the equipment ships, the signed report sits alongside the certificate of conformance for the order.

Common FAT problems

• Procedure written by the manufacturer alone, testing what already works.
• Software changed after the FAT, so the tested version is not the one shipped.
• Simulated inputs that do not reflect real process conditions.
• Punch items agreed verbally and lost before the site acceptance test.
• No calibration evidence for the instruments used to measure performance.