What Is SAT? Site Acceptance Test

Quick Answer

A Site Acceptance Test (SAT) is the formal verification of equipment or systems after installation at the project site. The SAT confirms that equipment—previously tested during the Factory Acceptance Test (FAT)—functions correctly in its installed environment, with actual field wiring, process connections, and integration with other systems. SAT is the final performance gate before pre-commissioning and commissioning activities begin.

FAT vs SAT

Aspect	FAT (Factory)	SAT (Site)
Location	Vendor’s facility	Project site
Timing	Before shipment	After installation
Connections	Simulated I/O, temporary hookups	Actual field wiring, piping, process connections
Integration	Standalone or partial integration	Full system integration (DCS, ESD, F&G)
Environment	Controlled factory conditions	Actual site conditions (temperature, humidity, dust)
Purpose	Verify manufacturing quality and basic function	Verify installed performance and system integration

Equipment That Requires SAT

System	SAT Scope
Distributed Control System (DCS)	All I/O points verified, control loops tuned, HMI screens confirmed, alarm management tested
Emergency Shutdown System (ESD)	Cause-and-effect matrix validated, shutdown sequences tested, voting logic confirmed
Fire and Gas Detection	Detector coverage confirmed, alarm/trip logic tested, notification systems verified
Motor Control Centers	Motor rotation checks, protection relay settings verified, interlocks tested
Actuated valves	Stroke time, fail-safe position, signal response from DCS/ESD
Metering systems	Calibration verified against site conditions, communication to DCS confirmed
Compressor/pump packages	Performance at site conditions, vibration readings, control system integration

SAT Procedure

Step	Activity	Responsible
1	Confirm equipment installation is complete (mechanical completion prerequisites)	Construction
2	Verify all field wiring, piping connections, and utility hookups	Construction / E&I
3	Perform loop checks (signal from field device to DCS and back)	Commissioning team
4	Execute SAT procedure per approved test protocol	Commissioning engineer
5	Record test results and compare against acceptance criteria	Commissioning team
6	Generate punch list for any deficiencies	Commissioning lead
7	Close punch items	Construction / vendor
8	Sign SAT completion certificate	Project / commissioning manager

Common SAT Deficiencies

Issue	Cause	Resolution
Signal mismatch	Field wiring swapped between terminals	Re-terminate wiring per loop diagram
Control loop instability	PID tuning parameters from FAT unsuitable for site conditions	Retune using actual process dynamics
Valve stroke time out of spec	Air supply pressure different from factory conditions	Adjust actuator air supply or regulator setting
Communication failure	Protocol mismatch between field device and DCS (HART, Modbus, Profibus)	Reconfigure communication parameters
Alarm flood	Alarm setpoints not rationalized for site conditions	Review and update alarm management database
Grounding issues	Instrument grounding not per specification	Install proper grounding per project electrical spec

Common Mistake

Skipping SAT for equipment that passed FAT without issues. FAT verifies factory conditions; SAT verifies installed conditions. Cable lengths, ambient temperature, electromagnetic interference, and actual process dynamics differ from the factory. An actuated valve that performed flawlessly during FAT may exhibit hunting or slow response at site due to longer pneumatic tubing runs or lower air supply pressure.

SAT Documentation

Document	Content
SAT procedure	Step-by-step test protocol with acceptance criteria
Loop check sheets	Each instrument loop verified from field to DCS
Test results	Measured values against specified values
Punch list	Deficiencies with priority classification (A, B, C)
SAT certificate	Signed confirmation that the system passed SAT

SAT completion is a prerequisite for pre-commissioning and commissioning. Systems that fail SAT cannot proceed to process fluid introduction. For inspection requirements during construction and hydrostatic testing that precedes SAT, see the detailed guides.

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