Services
Plant, Renewable & Oil & Gas Pre-Commissioning
Ensuring System Integrity Before Start-Up
Pre-commissioning is the critical phase that occurs after mechanical completion, preceding plant commissioning. It focuses on verifying the integrity, cleanliness, operability and readiness of all plant systems before they are energised for the first time.
MCCS International’s pre-commissioning specialists deliver a world-class service across the globe. Focusing on the downstream production and refinery of oil and gas, petrochemicals, power plants, and large industrial facilities.
What is Pre-Commissioning in Oil and Gas Projects?
Pre-commissioning is the phase after mechanical completion but before commissioning. It involves detailed checks and thorough tests to verify the integrity, cleanliness, operability, and readiness of all systems, including pipelines, before they are energised for the first time.
Oil and gas projects carry more volatile, flammable, and valuable materials, requiring expert attention to detail. No matter your pre-commissioning project, MCCS is committed to delivering a world-class service.
Why is Pre-Commissioning Important?
Pre-commissioning is important because it ensures that all equipment, systems, and processes verified during mechanical completion are tested, safe, and fully operational for energisation.
This reduces startup risks, preventing costly failures, and ensures regulatory compliance.
System Integrity Verification
The first stage of pre-commissioning is to perform inspections that include:
- Leak integrity inspections (gross air leak tests, reinstatement, box-up).
- Final P&ID conformity checks
- Rotating equipment (soft foot check, final shaft alignment, coupling & guarding, and pre-start mechanical checks)
- Instrumentation and continuity tests.
- Electrical tests of continuity, cable megger, grounding, AC/DC, UPS, etc.
- Safety device verification
- Firefighting system readiness checks
This verification confirms that mechanical completion met safety and operational standards, and the system can safely hand over to plant commissioning.
Cleaning & Flushing
Cleaning and flushing are critical to remove contaminants and prevent early equipment failure.
Types of cleaning and flushing MCCS executes:
- Chemical flushing
- High-velocity air flushing
- Nitrogen purging
- Oil flushing for rotating equipment
- Filter installation & inspection
MCCS ensures each subsystem meets cleanliness levels specified by design and OEM requirements.
Pressure Testing and Leak Verification
Pre-commissioning involves advanced integrity tests that ensure systems can handle operational conditions.
- Hydrotesting
- Pneumatic testing
- Nitrogen/helium leak testing
- Vacuum testing
- Pressure relief device calibration
Instrumentation & Control Verification
MCCS validates all instrumentation testing to ensure they communicate correctly with the control system before energisation:
- Continuity checks
- Loop checks
- Impulse line cleanliness
- Calibration verification
- Functional testing
Electrical Pre-Commissioning
MCCS conducts electrical integrity checks that include:
- Cable megger testing
- Continuity checks
- Switchboards, switchgears, panels, energisation preparation
- Motor Control Centre (MCC) readiness
- Transformer and generator pre-start inspections
- Grounding
- De-energised functional checks of instruments and motors
- AC/DC UPS
These verification checks ensure that the electrical systems can be safely energised during plant commissioning.
Handover to Commissioning
Once all tests are accepted, and inspection test records tracked, MCCS issues:
- Test packs compilation
- Checklists & reports
- Mark-up P&IDs
- Pre-Commissioning Completion or Ready for Commission Certificates
- Updated punch list
- Final system readiness and readiness reports
MCCS ensures complete transparency, compliance, and traceability with our proprietary software PUMA+. The systems are then formally handed over to commissioning teams for energisation and functional tests.
Choose MCCS As your Commissioning Vendor
Our focus is to thoroughly test and prepare subsystems for plant commissioning with full transparency, without exception. With over 30 years of experience, we are well-positioned to complete your plant, oil and gas projects ahead of activation.
MCCS has had the privilege of serving a diverse portfolio of international clients
