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Factory Acceptance Test (FAT): What It Checks, and How It Differs from a SAT
A factory acceptance test, or FAT, is where the buyer watches equipment run to spec at the vendor’s works, before it ships. Pass it and the kit is cleared for delivery. Fail it and the fixes happen on the maker’s floor, while they’re still cheap. Its sister test, the SAT, repeats the check once the equipment is installed on site.
What does a FAT actually check?
A FAT proves the equipment is ready to leave the factory, not just that someone bolted it together. You work through a few things:
- Every operating mode and control action, run against the spec.
- The e-stops, guards and trip logic get triggered on purpose, to prove they bite.
- Speed, throughput or output, measured against the contract figure.
- Faults get simulated so you can watch the right alarm and response fire.
- As-built drawings, manuals and certificates checked off against the list.
- Open defects go on the punch list, each with an owner, before anyone signs.
FAT or SAT: which is which?
Location and timing settle it. A FAT runs at the maker’s works before delivery. A site acceptance test runs after installation, on real utilities and real load. The FAT stops you shipping a lemon; the SAT proves the same kit still performs once it’s wired into your plant, as the first live milestone of commissioning.
What happens once the FAT passes?
Sign-off clears the equipment to ship. On site it gets re-checked through the SAT and then functional testing, so any damage in transit or install shows up before start-up. Any FAT punch items still open travel with the machine. They don’t get quietly dropped.
FAT vs SAT at a glance
The two acceptance tests people swap by mistake, side by side.
| Aspect | Factory Acceptance Test (FAT) | Site Acceptance Test (SAT) |
|---|---|---|
| Where | Vendor / maker's works | Your installation site |
| When | Before shipment | After installation |
| Conditions | Simulated / test utilities | Real utilities and load |
| Approves it for | Shipping | Commissioning |
| You walk away with | Signed FAT protocol | Signed SAT protocol |
Free FAT witness checklist and punch tracker
It records what you ran, what passed and every open punch item with an owner and a due date. Download the checklist (PDF). You can also complete the checklist digitally in flowdit on your phone, tablet or PC.
Related Terms
- Commissioning Process – the sequence FAT and SAT sit in.
- Pre-Commissioning – the cold checks before power goes on.
- Punch List – where open FAT defects live.
- Machine Commissioning – bringing a machine into service.
- Operational Readiness – the end you’re testing toward.
Further Reading
- Commissioning-Software – commissioning end to end
