Factory Acceptance and Site Acceptance Tests

Two tests, two different questions

Large or custom equipment is rarely tested just once. Two named events are common: the factory acceptance test (FAT), done at the supplier’s premises before shipping, and the site acceptance test (SAT), done after installation at the buyer’s location. Together they are often described as acceptance testing, and they are meant to answer different questions.

• FAT asks: does the equipment, as built, meet the specification and work properly in a controlled environment?
• SAT asks: does it still work after transport and installation, connected to the real utilities, controls and surroundings?

Neither replaces the other. Each catches problems the other cannot.

What a factory acceptance test checks

The FAT takes place where the supplier can fix things quickly: tools, spare parts and skilled staff are on hand, and nothing has yet been shipped. Because the machine is usually complete or nearly complete, it can be powered up under supplier-provided utilities and run through a test plan.

Typical FAT content includes:

• Documentation and build checks: comparing the equipment against drawings and the purchase specification, including components used, labeling and nameplate information
• Visual and mechanical inspection: quality of welds and finishes, guards, fasteners, lubrication points, access for service
• Electrical and controls checks: wiring inspection, power-up, input and output checks, and verification that the control program behaves correctly
• Safety function tests: emergency stops, interlocks and guarding responses, often checked against requirements for machine safety features
• Functional runs: operating through normal sequences, alarms and fault conditions
• Performance trials: where practical, running with representative material or load to see whether the machine reaches agreed performance levels

For equipment too large to assemble fully in the supplier’s workshop, the FAT may cover subsystems, with the rest left for the SAT. Controls are a good example: a control cabinet can be tested with simulators for the inputs and outputs it will later connect to.

Why test before shipping

Finding a wiring error or software bug at the supplier’s plant is usually far cheaper than finding it on a customer’s site where cranes, contractors and production schedules are waiting. A FAT also lets the buyer’s operators and maintenance people see the machine early, ask questions and notice design issues, such as awkward access to a filter, while changes are still practical.

Often the contract ties a payment milestone or shipping release to a passed FAT, with a list of outstanding items that must be closed before or after delivery. Terms vary by contract.

What a site acceptance test checks

After shipping, installation and connection to utilities, the SAT verifies the equipment in its real environment. What can change between factory and site is surprisingly large: transport damage, different power quality, different air or water supply, different ambient conditions, real product, and interfaces with other machines.

SAT content commonly includes:

• inspection for transport or installation damage
• verification that installation matches the drawings, including anchoring, piping and cabling
• re-checking of safety functions in the final installation, including emergency stop circuits tied into the plant
• verification of communications and signals exchanged with upstream and downstream equipment
• performance runs with actual product, at the speeds, rates and conditions the machine will see in production
• checks over a reasonable duration, since problems that show up only after several hours of running would be missed in a brief demonstration

Instruments may also be verified, which links to regular calibration, so readings can be trusted.

Test plans, witnesses and records

Both tests work best when they are planned in writing before they start. A test plan states each test, how it will be performed, what result counts as a pass and who needs to witness it. Without agreed pass criteria, it is hard to tell later whether an outcome was acceptable.

Witnesses typically include the supplier’s engineers and representatives from the buyer, such as operations, maintenance and sometimes safety or quality. Results are recorded on test sheets that are signed, dated and kept as part of the handover package. Records from the FAT are valuable at the SAT, because they let the team compare behavior before and after shipping.

Deviations are normal. When something fails, it is recorded, and the plan specifies whether the test can continue, must be repeated or can be closed later with a documented agreement. A short list of minor items remaining after acceptance is often formalized on a punch list with owners and dates.

Limits of acceptance tests

It is worth being realistic. Acceptance tests are samples of behavior over a limited time. A machine that passes them has shown it meets the tested criteria in the tested conditions; it has not been proved free of faults. Wear, rare operating conditions and long-term reliability are ultimately shown over months of production. For that reason, warranties and early-operation support are usually part of the arrangement too.

Also, a test is only as good as its design. If the specification is vague, acceptance tests may pass equipment that does not do what the buyer needed. Clear requirements written before purchase are the best way to avoid disagreement later.

Practical tips

1. Agree the acceptance criteria and test plan during contract negotiation, not shortly before the test.
2. Send the right people to the FAT, including those who will operate and maintain the machine.
3. Use the FAT results to prepare the site: if the test showed utility needs or access issues, address them before delivery.
4. Do not skip the SAT because the FAT went well.
5. Keep all signed records with the rest of the commissioning documentation.

This is general information about a common practice. Exact requirements depend on the contract, the industry and local regulations, and test work should be done by qualified personnel following manufacturer guidance.