When a production line is dismantled, transported, and reassembled at a new site, the reinstall is only half the job. The other half is proving the machine performs exactly as it did before — safely, at rated speed, and to quality specification. That proof comes from structured acceptance testing: the Factory Acceptance Test (FAT) and the Site Acceptance Test (SAT).

Too many relocation projects treat commissioning as an informal "switch it on and see." That approach hides defects until they surface during real production, when downtime is most expensive. A disciplined FAT/SAT process turns hand-over into a documented, contractual milestone that protects both the plant operator and the relocation contractor.

What FAT and SAT actually mean

The two tests serve different purposes and happen at different stages.

Factory Acceptance Test (FAT)

FAT is traditionally performed at the manufacturer's or integrator's premises before shipment — but in a relocation context it takes on a modified role. When a line already exists, a "pre-move FAT" is essentially a baseline capture: you document how the machine performs before disassembly. This baseline becomes the reference against which post-move performance is judged.

A pre-move baseline typically records:

Cycle times and throughput at rated conditions
Product quality parameters (dimensions, seal integrity, fill accuracy)
Power draw, air consumption, and utility loads
Alarm and interlock behavior
Software version, PLC parameters, and recipe backups
Vibration and noise readings on critical drives

Without this baseline, arguments about "the machine was always like that" become impossible to resolve.

Site Acceptance Test (SAT)

SAT takes place at the new location after installation, leveling, alignment, and utility connection. Its goal is to confirm that the equipment reaches the same — or contractually agreed — performance under real site conditions: local power quality, ambient temperature, compressed-air supply, and the actual product being run.

SAT is the formal gate that releases the line to production. It should end with a signed protocol.

Why acceptance testing matters after a relocation

A move introduces variables that never existed at the original site. Even a perfectly executed relocation can expose:

Different power supply characteristics (voltage, frequency stability, harmonics)
Compressed-air pressure or dew-point differences
New foundation stiffness affecting vibration
Transport-induced misalignment or loosened connections
Ambient humidity and temperature affecting sensors and product

Acceptance testing systematically surfaces these issues in a controlled window instead of during a rushed production start.

Building the acceptance test protocol

A good protocol is written before the machine is switched on and agreed by all parties. It should be specific and measurable — "runs fine" is not an acceptance criterion; "produces 12,000 units/hour with reject rate ≤0.5%" is.

Core sections of a SAT protocol

Scope and reference documents — link to the pre-move baseline and OEM manuals.
Pre-conditions — leveling within tolerance, media connected, safety systems restored.
Static checks — wiring continuity, earthing, pneumatic leaks, lubrication levels.
Functional checks — manual jog of each axis, sensor triggering, valve actuation.
Safety verification — emergency stops, light curtains, interlocked guards, LOTO points.
Dry run — full cycle without product.
Wet/production run — real product at increasing speed to rated output.
Performance run — sustained operation (often several hours) to confirm stability.
Acceptance criteria and sign-off — pass/fail thresholds and open-punch-list handling.

The commissioning sequence in practice

Commissioning after a move should follow a deliberate escalation from cold checks to full-rate production. Rushing straight to speed risks damage and masks the root cause of problems.

Step 1 — Cold verification

With power isolated, confirm mechanical assembly, torque of critical fasteners, alignment of drives and couplings, and integrity of all reconnected media lines. Verify that safety circuits are complete.

Step 2 — Power-up and I/O check

Energize control systems first. Confirm the PLC boots to the correct program and that every input and output maps correctly. Compare parameters against the backup taken before dismantling. This is where restoring an accurate configuration backup pays off.

Step 3 — No-load and slow-speed running

Run individual drives and modules empty, listening for abnormal noise and watching for overheating, incorrect rotation, or vibration above baseline. Correct alignment issues now, not later.

Step 4 — Product trials

Introduce product at reduced speed. Inspect quality output closely, then ramp toward rated throughput in stages, verifying rejects and downtime at each level.

Step 5 — Sustained performance run

Run at full rate for an agreed duration. Thermal and wear-related faults often appear only after the line reaches steady-state temperature.

Roles, responsibilities, and documentation

Acceptance testing works only when responsibilities are clear before the test day.

Plant operator/production provides product, operators, and defines quality criteria.
Relocation contractor delivers correct mechanical installation and supports commissioning.
OEM or specialist technician may be required for proprietary software, recalibration, or warranty-sensitive equipment.
HSE/safety verifies that guards, interlocks, and — where applicable — conformity requirements are satisfied before production release.

Every test should generate records: measurement sheets, screenshots of controller values, photos, and a punch list of open items with owners and deadlines. These documents form the audit trail for the machine's future maintenance and any warranty claims.

Common pitfalls to avoid

No baseline. Without pre-move data, you can't prove the line performs "as before."
Skipping the dry run. Feeding expensive product into an unverified line wastes material and can crash the machine.
Testing with the wrong product. Acceptance must use representative product, not an easy sample.
Ignoring utilities. Under-sized air lines or unstable power will fail a SAT that mechanically looks perfect.
Vague criteria. "Looks good" invites disputes; use numeric thresholds.
No sign-off. An unsigned SAT leaves liability undefined if problems emerge weeks later.

Tying acceptance testing to the whole project

SAT is not an isolated event — it is the payoff for good practice earlier in the move: labeling and backing up controls, protecting connectors during transport, leveling to tolerance, and reconnecting utilities correctly. When those steps are done well, acceptance testing is a confirmation rather than a firefight.

For plant managers planning a relocation, the practical takeaway is simple: define your acceptance criteria at the start, capture a solid pre-move baseline, and hold a structured, documented SAT before releasing the line. That discipline shortens the ramp-up curve, reduces surprise downtime, and gives everyone a clear, evidence-based moment when the line is officially back in production.

FAT vs SAT: Acceptance Testing After Machine Relocation