Factory Acceptance Testing (FAT) is the systematic inspection and verification process that confirms instruments and equipment fully comply with contractual specifications, safety requirements, and performance criteria before shipment from the manufacturer's facility. This guide covers FAT procedures, tested equipment categories, testing items, methods, applicable standards, and frequently asked questions to help buyers, engineers, and quality professionals execute reliable acceptance programs.
Technical Overview
Factory Acceptance Testing (FAT) is a formal verification procedure performed at the manufacturer's facility before instruments and equipment are released for shipment. Its core objective is to confirm that the delivered products conform to the purchase contract specifications, applicable national and international standards, and the performance parameters declared by the manufacturer. A properly executed FAT provides objective evidence that defects are identified and corrected prior to delivery, thereby reducing commissioning delays, installation risks, and warranty disputes.
FAT is distinct from Site Acceptance Testing (SAT). FAT is conducted under controlled factory conditions before shipment, while SAT verifies installed performance at the end user's location after delivery, installation, and commissioning. Together, the two processes form a complete acceptance chain that protects both the supplier and the purchaser.
A typical FAT program includes the following key elements:
- Review of technical documentation, drawings, certificates, and type test reports
- Visual, structural, and dimensional inspection of the equipment
- Electrical safety verification, including insulation, dielectric, and grounding tests
- Functional and performance testing against defined acceptance criteria
- Environmental, EMC, endurance, or ingress protection testing where required
- Issuance of a formal FAT report and handling of non-conformances
Commonly referenced standards include the IEC 61010 series for measurement and laboratory equipment safety, IEC 60204-1 for electrical equipment of machinery, IEC 61439 for low-voltage switchgear and controlgear assemblies, the IEC 60068 series for environmental testing, IEC 60529 for ingress protection, and applicable national standards such as the GB/T series. FAT is frequently witnessed or executed by independent third-party testing and inspection organizations to ensure impartiality.
Testing Samples
Factory acceptance testing applies to virtually every category of industrial and laboratory equipment. The most common sample types include:
Electrical and Power Distribution Equipment
High- and low-voltage switchgear, power distribution cabinets, motor control centers (MCC), control panels, transformers, variable frequency drives (VFD), uninterruptible power supplies (UPS), busbars, and power cables. These items undergo rigorous electrical safety and functional interlock verification before energization at the user's site.
Automation and Control Systems
PLC and DCS cabinets, SCADA and HMI systems, remote I/O stations, sensors, transmitters, flowmeters, and actuators. FAT for these systems typically includes point-by-point I/O verification, loop checks, communication protocol validation, and software function tests.
Mechanical Equipment
Pumps, valves, compressors, fans, blowers, gearboxes, mixers, pressure vessels, and heat exchangers. Mechanical FAT emphasizes material verification, hydrostatic or pneumatic pressure tests, performance curves, vibration, and noise measurement.
Measurement and Analytical Instruments
Pressure gauges and transmitters, temperature sensors and thermometers, gas and liquid analyzers, chromatographs, electronic balances, and other precision instruments, with a focus on accuracy, linearity, repeatability, and calibration traceability.
Medical and Laboratory Equipment
Diagnostic devices, sterilizers, biosafety cabinets, refrigeration units for pharmaceutical storage, and general laboratory instruments verified in accordance with IEC 61010 and, for regulated industries, GMP equipment qualification requirements.
Special and Statutory Equipment
Boilers, pressure piping components, lifting machinery and elevator components, and other equipment subject to statutory supervision, where factory testing and certified documentation are legally mandated.
Testing Items
The scope of testing items is defined by the equipment type, the contract, and the applicable standards. A comprehensive FAT generally covers the following categories:
- Documentation review: drawings, datasheets, material certificates, calibration certificates, type test reports, and conformity declarations
- Appearance and workmanship inspection: surface finish, coating quality, welding quality, labeling, nameplate data, and assembly integrity
- Dimensional verification: overall dimensions, mounting hole positions, terminal clearances, and installation interfaces compared against approved drawings
- Electrical safety tests: insulation resistance, dielectric withstand (hipot), protective earth continuity, and leakage current
- Functional testing: operating logic, control sequences, alarm and interlock behavior, indication accuracy, and communication interfaces
- Performance testing: measurement accuracy, range, linearity, hysteresis, repeatability, response time, output signals, and power consumption
- Environmental adaptation: operating temperature and humidity limits, vibration and shock resistance, and IP ingress protection rating
- Electromagnetic compatibility (EMC): conducted and radiated emissions as well as immunity to interference where specified
- Endurance and reliability: burn-in tests, continuous rated-load operation, duty cycle verification, and overload behavior
- Auxiliary measurements: noise levels, surface temperature rise, and protective device coordination
Testing Methods
FAT methods combine standardized test procedures with equipment-specific acceptance criteria agreed in the FAT protocol before testing begins. The principal methods are described below.
Visual and Dimensional Inspection
Trained inspectors examine the equipment against detailed checklists, verifying construction, marking, and workmanship. Dimensions are measured using calipers, micrometers, height gauges, coordinate measuring machines (CMM), or laser measurement systems, and compared with tolerances stated on the approved drawings.
Electrical Safety Testing
Insulation resistance is measured with a megohmmeter, typically applying 500 V DC or 1000 V DC between live parts and the enclosure, with minimum resistance values defined by the relevant standard. Dielectric withstand (hipot) testing applies a specified AC or DC test voltage, commonly for 60 seconds, to detect insulation breakdown. Protective bonding continuity is verified with a low-resistance tester to confirm the protective earth path, and leakage current is measured under normal and single-fault conditions.
Functional and Performance Testing
Equipment is energized and exercised through its full functional envelope. Process signals are simulated using calibrators and signal generators; measurement instruments are compared against reference standards traceable to national metrology institutes. For automation systems, every I/O point, alarm, interlock, and communication link (such as Modbus, PROFIBUS, or Ethernet protocols) is verified point by point against the I/O list.
Environmental and EMC Testing
Climatic chambers, vibration shakers, and IP test apparatus are used to demonstrate performance under specified environmental conditions, following the IEC 60068 test method family. Ingress protection is assessed per IEC 60529 using dust and water jet tests. Where required, EMC testing is performed in accordance with the IEC 61000 and CISPR standards to confirm both emissions limits and immunity levels.
Load, Endurance, and Special Tests
Mechanical and electrical equipment is operated at rated load and, where specified, under overload or duty cycle conditions to demonstrate thermal stability and reliability. For pressure equipment, hydrostatic or pneumatic pressure tests are performed at prescribed test pressures with hold times and inspected for leakage and permanent deformation.
Documentation and Non-Conformance Handling
All measurements are recorded in structured test records and compared with the acceptance criteria. Any deviation is raised as a non-conformance report (NCR), corrective actions are implemented by the manufacturer, and affected items are re-tested. The FAT is concluded with a signed report that serves as the formal basis for shipment release and payment milestones.
Applications
Factory acceptance testing is applied across a broad range of industries and procurement scenarios:
- Manufacturing procurement: verification of custom machinery and production lines before handover from the machine builder
- Power and utilities: acceptance of switchgear, protection relays, transformers, and distribution equipment for generation, transmission, and distribution projects
- Oil, gas, and petrochemical: testing of skid-mounted packages, valves, analyzers, and control systems for hazardous area installations
- Pharmaceutical and life sciences: FAT as an integral part of GMP equipment qualification, feeding into design, installation, and operational qualification (DQ/IQ/OQ)
- Rail transit and transportation: verification of onboard and wayside electrical and electronic equipment against demanding reliability and environmental requirements
- Medical devices: pre-delivery verification of safety and performance for regulated medical equipment
- Import and export trade: third-party factory testing and inspection supporting customs clearance and international commodity inspection
- Government and public tenders: witnessed acceptance testing providing independent evidence of compliance for publicly funded projects
FAQ
What is the difference between FAT and SAT?
FAT is performed at the manufacturer's facility before shipment under controlled factory conditions, verifying that the equipment as built meets the specified requirements. SAT is performed at the end user's site after delivery, installation, and commissioning, verifying system-level performance in the actual operating environment, including interfaces with existing plant systems.
Who performs factory acceptance testing?
Testing may be performed by the manufacturer's quality team with the buyer present as a witness, or independently by an accredited third-party testing and inspection organization. Third-party execution is preferred for public tenders, regulated industries, and international purchases because it provides impartial, technically authoritative reports.
What documents are issued after a successful FAT?
The typical deliverables include the approved FAT protocol, completed test records and checklists, calibration certificates for instruments used in testing, non-conformance reports and closure evidence if applicable, and a signed FAT certificate or report that authorizes shipment.
How long does a factory acceptance test take?
The duration depends on equipment complexity. Simple instruments may be verified within a few hours, while complex systems such as switchgear assemblies, packaged skids, or integrated automation systems may require several days or weeks, particularly when endurance, burn-in, or extended functional testing is specified.
What happens if the equipment fails the acceptance test?
Failures are documented in a non-conformance report. The manufacturer implements corrective actions, repairs or reworks the affected items, and the failed tests are repeated until all acceptance criteria are met. Shipment is released only after all open non-conformances are closed and the purchaser or third party signs the final report.
Which standards govern factory acceptance testing?
The applicable standards depend on the product category. Frequently used references include IEC 61439 for low-voltage switchgear assemblies, IEC 60204-1 for electrical equipment of machinery, IEC 61010 for measurement and laboratory equipment, IEC 60068 for environmental testing, IEC 60529 for IP codes, and the IEC 61000 series for EMC, supplemented by project-specific contractual specifications and national standards.