7. Construction and Installation

Once engineering, procurement, and material deliveries reach the required stage, construction begins or progresses significantly.

Construction converts engineering documents into a physical facility.

Depending on the project, activities can include:

Civil construction

Site preparation
Earthworks
Foundations
Roads
Buildings
Drainage

Structural construction

Steel fabrication
Pipe rack erection
Equipment structures
Platforms
Access systems

Mechanical construction

Equipment installation
Vessel erection
Pump installation
Compressor installation
Tank construction

Piping construction

Pipe fabrication
Spool fabrication
Erection
Welding
Nondestructive examination
Pressure testing
Flushing and cleaning
Insulation
Painting

Electrical construction

Cable tray installation
Cable pulling
Transformer installation
Switchgear installation
Earthing
Lighting

Instrumentation construction

Instrument installation
Tubing
Junction boxes
Cable installation
Control system installation
Instrument calibration

Construction management

Construction must be controlled through:

Safety management
Quality management
Schedule control
Material management
Inspection
Progress measurement
Permit-to-work systems
Construction planning

The goal is not simply to construct the facility, but to construct it safely, correctly, and according to the approved engineering design.

8.Pre-Commissioning

Before hydrocarbons or process fluids are introduced into the facility, extensive testing and preparation must take place.

This is known as pre-commissioning.

Typical activities include:

Cleaning
Flushing
Air blowing
Chemical cleaning
Hydrostatic testing
Leak testing
Electrical testing
Cable testing
Instrument calibration
Loop checking
Equipment inspection
Motor solo runs
System checks

The objective is to ensure that individual systems are mechanically complete and ready for commissioning.

Mechanical Completion

A system is considered mechanically complete when construction activities and required inspections for that system have been completed according to project requirements.

Documentation such as:

Punch lists
Inspection records
Test certificates
Pressure test records
Calibration certificates

helps demonstrate completion.

9.Commissioning and Start-up

Commissioning bridges the gap between construction and operation.

During commissioning, systems are energized, tested, functionally checked, and placed into service.

Typical activities include:

Energizing electrical systems
Testing control systems
Testing safety systems
Introducing utilities
Testing rotating equipment
Checking process systems
Testing interlocks
Functional testing
Performance testing

Eventually, the facility moves toward start-up.

Start-up

During start-up, the facility begins operating with process fluids or hydrocarbons.

Engineers and operators carefully monitor:

Pressure
Temperature
Flow
Vibration
Equipment performance
Process stability
Safety systems
Product quality

Start-up is one of the most critical stages because the facility transitions from a constructed asset into a live operating system.

10. Operations and Maintenance

Once the facility achieves stable operation, it enters its longest phase: operations.

An oil & gas facility may operate for decades.

During this stage, the primary objectives are:

Safe operation
Reliable production
Asset integrity
Efficient energy consumption
Regulatory compliance
Environmental performance
Cost control

Maintenance activities

Maintenance can include:

Preventive maintenance
Planned maintenance performed at predetermined intervals.

Predictive maintenance
Maintenance based on equipment condition and monitoring data.

Corrective maintenance
Repair performed when a fault or failure is identified.

Turnaround maintenance
Major planned shutdowns for inspection, maintenance, repair, and modification.

Asset integrity

Asset integrity management is particularly important in oil & gas facilities.

Engineers monitor:

Corrosion
Erosion
Fatigue
Cracking
Vibration
Pressure equipment condition
Pipeline integrity
Structural integrity
Safety systems

The goal is to ensure that equipment remains fit for service throughout its intended life.

11. Brownfield Modifications and Upgrades

The project life cycle does not necessarily stop when the facility begins operating.

Operating facilities frequently require modifications.

These projects are often called brownfield projects, while new facilities are generally referred to as greenfield projects.

Brownfield activities may include:

Capacity expansion
Debottlenecking
Equipment replacement
Pipeline modifications
New tie-ins
Process improvements
Safety upgrades
Emissions reduction projects
Digitalization
Energy-efficiency improvements

Brownfield engineering can be particularly challenging because the facility is often operating while modifications are being designed and installed.

Engineers must consider:

Existing conditions
Available space
Live systems
Shutdown requirements
Tie-in points
Existing drawings
Constructability
Safety

12. Decommissioning

Eventually, an oil & gas facility may reach the end of its economic or technical life.

The facility may be decommissioned because of:

Declining production
Aging infrastructure
High operating costs
Regulatory requirements
Safety concerns
Changes in market conditions
Replacement by newer facilities

Decommissioning involves safely taking the facility out of service.

Activities may include:

Shutdown planning
Isolation
Depressurization
Removal of hydrocarbons
Cleaning
Disconnection
Equipment removal
Pipeline abandonment or removal
Structural dismantling
Waste management

For offshore facilities, decommissioning can involve complex subsea operations and environmental considerations.

13. Site Restoration and Project Closure

The final stage involves restoring the site as required by regulations, contractual obligations, and the approved decommissioning strategy.

Activities can include:

Site cleanup
Waste disposal
Environmental remediation
Removal of temporary facilities
Restoration of land
Final inspections
Regulatory approvals
Documentation and records closure

The project team also captures lessons learned.

These lessons can be valuable for future projects.

For example:

What engineering decisions worked well?
Which procurement activities caused delays?
Which construction methods were effective?
Where did design changes occur?
What safety issues were identified?
What could have been done differently?

This knowledge feeds into future projects and helps organizations continuously improve.

The Complete Lifecycle Of An Oil & Gas Project: From Concept to Closure And Beyond PART 2