Direct Answer

A factory acceptance test (FAT) for a pressurised offshore container should verify the complete safety sequence, not only individual equipment operation. The test must confirm structural and documentation status, electrical safety, purge and pressurisation, fire-and-gas detection, cause-and-effect actions, HVAC, emergency systems, communications and project interfaces within the agreed factory boundary.

The approved FAT procedure should define inputs, simulated conditions, expected outputs, acceptance criteria, witness responsibilities and required records for every test. A generic checklist cannot replace project-specific review of the hazardous-area classification, IEC 60079-13 protection concept, A60 boundaries and platform interfaces.

What Is the Purpose of the FAT?

The FAT answers a practical question: Does the manufactured module perform the approved functions before it is shipped to site?

It should detect wiring errors, incorrect alarm logic, unverified interlocks, equipment mismatches, documentation gaps and interface problems while the module is still accessible to the manufacturer. It does not prove that site utilities, external ducting, upstream protection or platform control systems will operate correctly after installation; those items require site acceptance and commissioning.

Which FAT Sections Should Be Included?

How Should the Pressurisation Sequence Be Tested?

The test should follow the approved protection concept and sequence. A typical verification includes:

1. Safe initial state: Confirm that protected non-Ex equipment cannot be energised before the required conditions are satisfied.

2. Protective-air source: Start the designated fan and verify fan status, intake conditions and relevant alarms.

3. Purge: Demonstrate the required purge airflow or volume-change sequence for the approved duration.

4. Pressure establishment: Confirm that the room reaches and maintains the specified differential pressure or airflow condition.

5. Permission to energise: Verify that the control system enables protected equipment only after the complete permissive sequence is satisfied.

6. Door operation: Test pressure recovery and alarms after normal door or airlock operation, as defined by the project.

7. Loss of pressure or airflow: Simulate a fan failure, open door, blocked path or sensor input and verify the required alarm and shutdown timing.

8. Recovery: Verify reset permissions and the required purge or restart sequence before re-energisation.

Record actual values and times. “Pass” without measured pressure, airflow, delay or trip data is difficult to audit and difficult for an operator to reuse during commissioning.

How Should Fire-and-Gas Cause and Effect Be Tested?

Each initiator should be tested against every required output in the approved matrix. Inputs may be introduced by detector test gas, approved simulators or controlled contact injection, depending on the equipment and test procedure.

The test should verify:

• local audible and visual alarms;
• alarm indication on the CPFG or other control panel;
• fan start, stop or changeover;
• fire-damper and ventilation-damper positions;
• isolation of protected or non-essential electrical loads;
• operation of emergency shutdown outputs;
• retained power to safety-critical equipment;
• remote alarm and status signals;
• event sequence and time stamps;
• latching, reset and restart permissions.

Detector activation alone is not a complete test. The final actuator position and electrical state must be confirmed.

What Electrical Tests Are Required?

The FAT should include the tests required by the approved design, applicable standards and equipment instructions. Typical checks include:

• protective-conductor and bonding continuity;
• insulation-resistance tests at the appropriate stage;
• phase sequence, voltage and frequency checks;
• circuit-breaker and protection-device settings;
• panel power-up and control-voltage checks;
• emergency-stop circuits;
• UPS or battery-backed safety loads;
• lighting and emergency lighting;
• Ex-equipment tag, marking and certificate-schedule verification;
• cable gland, MCT and penetration inspection;
• panel and field-device loop checks.

Test voltages and methods must be compatible with connected electronic equipment. Sensitive devices may need to be isolated before insulation testing.

What Should Be Checked on the A60 Boundary?

The inspection should verify that the installed construction matches the approved fire-rating scope. Check:

• insulation type, thickness, orientation and fixing method;
• A60 doors, escape hatches and hardware;
• cable and pipe transit systems;
• fire and ventilation dampers;
• joints, corners and interfaces with structural members;
• damage or unsealed penetrations after equipment installation;
• product labels, approvals and installation records.

The FAT does not repeat a laboratory fire test. It verifies that the production module uses the approved construction and that installation evidence is complete.

Which HVAC and Habitability Checks Matter?

Pressurisation and air conditioning serve related but different purposes. The FAT should confirm the available factory-scope functions, including:

• HVAC operating modes and control points;
• supply, return and exhaust airflow direction;
• temperature and humidity sensor readings;
• condensate drainage;
• duty/standby changeover where provided;
• filter, fan and high/low-temperature alarms;
• interaction between process exhaust and room pressure;
• noise or vibration checks where specified.

A short no-load run cannot prove full thermal performance at the project design ambient and internal heat load. If a heat-load test or performance simulation is required, it must be separately defined.

What Belongs in the Final FAT Report?

The report should contain:

• approved procedure and attendance record;
• completed test sheets with actual measured values;
• calibration details for test instruments;
• alarm, trip and response-time records;
• photographs or traceable evidence where required;
• software and configuration revision numbers;
• punch-list items, owner, due date and closure evidence;
• deviations, concessions and approved dispositions;
• redlined drawings and final-document action list;
• release status and conditions for shipment.

Open items should be classified by safety and operational impact. A module should not be released on the basis of an unstructured punch list that does not identify which items prevent shipment or energisation.

What Must Be Retested at Site?

Site acceptance testing should verify functions affected by transport, installation and external systems, including:

• final power, grounding and upstream protection;
• external ducting and protective-air intake location;
• platform F&G, ESD, PA/GA and communications interfaces;
• installed cable and pipe penetrations;
• final HVAC heat rejection and drainage;
• lifting or transport damage;
• full shutdown and restart sequences with site systems;
• operator access, escape routes and emergency procedures.

Frequently Asked Questions

1. Is a FAT certificate the same as third-party certification?

No. A FAT report records agreed functional tests. Structural, lifting, fire-rating and hazardous-area conformity documents have separate scopes and approval routes.

2. Can the FAT be completed without the platform control system?

Yes, if external signals are simulated with an approved method and all interface assumptions are recorded. The real end-to-end interface must then be tested during site acceptance.

3. Should every gas detector be tested with gas?

The method depends on the detector, manufacturer instructions and approved test procedure. A loop simulation checks logic and wiring but may not verify sensor response. The FAT should distinguish detector functional tests from control-loop simulations.

4. Does passing the pressure test prove compliance with IEC 60079-13?

No. Compliance depends on the complete design, assessment, verification, controls and marking requirements. One pressure reading does not verify purge, monitoring, failure response or the suitability of the protective-air arrangement.

5. Who should witness the FAT?

Witness points should be defined in the inspection and test plan. Depending on the contract, attendees may include the manufacturer, purchaser, EPC, end user and certification or inspection body.

Conclusion

The FAT for a pressurised offshore container should demonstrate an integrated and measurable safety sequence. The strongest procedure connects every hazard input to a defined control action, test method, acceptance value and record. It also states clearly what remains for site acceptance, preventing factory sign-off from being mistaken for complete offshore commissioning.

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