FAT vs. SAT: Manufacturing Equipment Acceptance Testing Guide

Factory acceptance testing (FAT) and site acceptance testing (SAT) are two different verification stages in a manufacturing equipment launch. Both help demonstrate that equipment meets agreed requirements, but they answer different questions and occur at different points in the equipment lifecycle.

FAT vs. SAT: the key difference

FAT is normally performed at the equipment manufacturer's or integrator's location before shipment. It checks agreed machine functions, documentation, controls, safety-related items, and performance under available test conditions. SAT is performed after delivery and installation at the destination site. It verifies equipment in its installed environment, including site utilities, interfaces, installation conditions, and operating readiness.

What should be included in a manufacturing equipment FAT?

1. Approved acceptance criteria: map each applicable test to a specific equipment requirement, drawing, or specification.
2. Safety and controls: check agreed interlocks, protective devices, stop functions, alarm behavior, and control sequences using the applicable safety plan.
3. Mechanical and electrical function: assess dimensions, actuation, sensors, motion, interfaces, and available equipment performance.
4. Documentation: review manuals, drawings, software and configuration records, calibration evidence, spares, and maintenance provisions as contracted.
5. Deviations: record failed or incomplete tests, owners, corrective actions, retest evidence, and acceptance dispositions.

A FAT is not automatically a production-capability demonstration. The supplier's site may not reproduce your actual process inputs, upstream/downstream equipment, operators, utilities, or sustained cycle conditions.

What changes when you move to SAT?

SAT should revisit requirements that depend on the plant environment: incoming utilities, network and controls connectivity, installed guarding, material handling interfaces, installation alignment, operating sequences, and site-specific alarms. Confirm that FAT deviations are closed or formally dispositioned before accepting dependent SAT activities.

For production lines, SAT is generally followed by additional steps such as process qualification, capability assessments, operator and maintenance readiness, and run-at-rate verification. The exact sequence should follow project contracts and applicable quality and safety requirements.

How do you prevent FAT and SAT issues from delaying the launch?

1. Define measurable requirements and evidence owners before issuing the supplier purchase order.
2. Build a traceability map from requirements to FAT, SAT, and subsequent verification stages.
3. Agree on test conditions and sample materials before scheduling FAT.
4. Maintain one controlled punch list with severity, owners, due dates, and retest evidence.
5. Separate test execution from test acceptance: a completed test with a failing result is not accepted.
6. Establish shipment, site-acceptance, and production-readiness gate criteria in advance.

FAT to SAT handoff checklist: what should transfer with the machine?

Before equipment leaves the supplier, agree on a documented handoff package so the site team can verify the installed machine without repeating unresolved factory-stage work.

1. Approved requirements and FAT results: retain the acceptance criteria, test records, supporting evidence, and authorized signoffs.
2. Open-item and deviation register: identify severity, accountable owner, target closure date, and the test or evidence required to close each item.
3. As-built documentation: collect applicable electrical and mechanical drawings, controls and software versions, manuals, spare-parts information, and calibration records.
4. Site prerequisites: confirm foundations, utilities, network interfaces, material flow, rigging, installation access, and safety responsibilities.
5. SAT test plan: assign test owners and define site-specific acceptance criteria, test materials, retest rules, and signoff authority.
6. Production-readiness gates: distinguish SAT completion from operator training, process qualification, run-at-rate, and final operational release.

Need a structured starting point? Get the free 35-point FAT checklist by email. For tracking requirements, FAT findings, SAT evidence, action owners, and launch gates together, see ELS Professional — Equipment Launch System.

Frequently asked questions

Can equipment ship with open FAT items?

Sometimes, but shipment disposition depends on the contract, risk, criticality, and formal approval. An open-item list should identify which issues must be closed before shipment and which can be resolved at the site. Never treat an open safety-critical issue as acceptable without the required engineering and safety approvals.

Does a passed FAT mean the machine is ready for production?

No. A passed FAT indicates the agreed factory-stage acceptance conditions were met. Installation, site testing, process qualification, and sustained production demonstration may still be required.

How should a FAT checklist be structured?

Include requirement ID, test description, acceptance criteria, procedure or method, recorded result, pass/fail status, evidence, deviation reference, and signoff responsibility. Use our free 35-point manufacturing equipment FAT checklist as a starting point.

Tools for managing the full equipment launch

If you need more than a single checklist, ELS Professional — Equipment Launch System provides an editable Excel framework for requirements, supplier evaluations, FAT, site readiness, SAT, qualification, run-at-rate verification, and action tracking.

Vision Launch Systems materials are general planning resources, not a substitute for contractual acceptance requirements, machine-safety assessments, or engineering approvals.