Theory

Pre-commissioning is a prior step to make any plant fully functional. The steps involved during pre-commissioning are listed below. Every step and its sequence is very important and in case the engineer in-charge misses any step it will lead to further complication and delay in pre-commissioning.

1. Documentation Review

Review of project documents, including:

• P&IDs (Piping and Instrumentation Diagrams)
• Process flow diagrams
• Instrumentation and electrical diagrams
• Mechanical and piping drawings
• Vendor documentation
• Operation and maintenance manuals

It is always a recommended practice to keep all the documents which are up to date (latest version) for ready reference. It is quite likely that the team need to refer these documents quite frequently. It is assumed that you are spear heading this project since its inception. The experience of many experienced site engineer reveals that the biggest hurdle is faced by site engineers is unavailability or previous versions of the documents available with the team.

2. Site Preparation

• Ensure site is ready for commissioning, including:
• Clearing of construction debris
• Installation of necessary utilities (e.g. power, water, air)
• Provision of access roads and walkways
• Installation of safety equipment (e.g. fire extinguishers, first aid kits) Before mobilizing or announcing the pre-commissioning schedule it is essential to check the ground realities. It is expected that the site is ready may not 100% but the clearance for few test set-ups must be ensured. The most important aspect of readiness is availability of all the utilities like electricity, water, instrument air etc. without fail.

3. Equipment Inspection

• Visual inspection of equipment, including:
• Verification of equipment installation and alignment
• Check for damage or defects
• Verification of equipment identification and labeling While starting the pre-commissioning activities it is essential to visually inspect the installations of all field instruments for its correct installation as per manufacturer’s recommended practices and standard. The tag numbers need to verified as per P&I diagram, and installation drawings.

4. Instrumentation and Electrical Testing

• Testing of instrumentation and electrical systems, including:
• Loop checking and calibration of instruments
• Testing of electrical circuits and wiring
• Verification of instrument and electrical system functionality Most crucial part of the pre-commissioning activity will be testing of instruments and control system. The pre-requisite is to charge the local and main control panels and all safety trials of the electrical system including LT side and Diesel Generator set is completed.

5. Piping and Tubing Testing

• Testing of piping and tubing systems, including:
• Hydrostatic pressure testing
• Pneumatic pressure testing
• Leak testing
• Verification of piping and tubing system integrity For the safe operation of the plant it is necessary that the piping including impulse piping must sustain the safe pressure limit of the pipe lines on which the instrument is installed. The leak being the most critical aspect in instrument lines and soap test must be performed for all instrument air lines.

6. Mechanical Completion

• Verification of mechanical completion, including:
• Verification of equipment installation and alignment
• Check for proper installation of mechanical components (e.g. valves, pumps, motors)
• Verification of mechanical system functionality This type of checking is mostly handled by mechanical group as the process group is involved in this activity. The impact of any deviation while installing pumps or valves will be crucial as these are most important items of the plant.

7. Safety and Environmental Checks

• Verification of safety and environmental systems, including:
• Fire suppression systems
• Emergency shutdown systems
• Ventilation and exhaust systems
• Environmental monitoring systems It's a joint activity of entire team involved in pre-commissioning. Looking at safety of plant and personnel this activity needs to be handled with utmost care and pre approving fire alarms, and allied systems is a must before charging any panel or water trial.

8. Pre-Commissioning Cleaning

• Cleaning of equipment and systems, including:
• Chemical cleaning of piping and equipment
• Mechanical cleaning of equipment and systems
• Verification of cleanliness and freedom from contaminants While installing and fabricating the lines a lot of welding burr must have deposited either inside or outside of the lines. Without cleaning if we start the system it is quite likely that the sensors when comes in contact with particles will damage and in some cases the lines can be choked. It is always a recommended practice to isolate the field instruments by closing instrument isolation valves or physically disconnecting the instruments from the locations.

9. Functional Testing

• Functional testing of systems and equipment, including:
• Testing of control systems and instrumentation
• Testing of electrical and mechanical systems
• Verification of system functionality and performance The testing of control system is carried at two places one at the system integrator’s premise which is basically a simulation/emulation and the other is carried out at site after installing it in control panel. At this time the wiring with field instrument is also complete the instruments will communicate with the control system. Most important care has to be taken while charging the control system is earthing. It is recommended and followed that the instrument earthing must be separate from electrical earthing.

10. Operator Training

• Training of operators, including:
• Familiarization with plant systems and equipment
• Training on operation and maintenance procedures
• Verification of operator competence Training operators before final commissioning is important as the success depends on how much these operators have learned and practiced. It is quite likely that the SCADA screens must have changed and navigation might be different or few process flows are different. It is also recommended that the safety aspects alarms and events need to be demonstrated properly to these operators.

11. Development of Commissioning Procedures

• Development of commissioning procedures, including:
• Development of startup and shutdown procedures
• Development of normal operation procedures
• Development of emergency response procedures Pre commissioning is a pre-requisite for the final commissioning and hand over activity, the lessons learnt will decide the procedures for start-up and shutdown including emergency shutdown. As the hazard is less as compared to final trial it is always recommended that the processes need to be set before the final commissioning means during this phase.

12. Development of Testing and Inspection Plans

• Development of testing and inspection plans, including:
• Development of testing and inspection schedules
• Identification of testing and inspection requirements
• Verification of testing and inspection procedures There are certain guide lines for generating testing schedules for all the field instruments as well as panel mounted instruments mandated by regulatory authorities or instrument manufacturer. The schedule needs to be evolved during this phase.

13. Coordination with Vendors and Contractors

• Coordination with vendors and contractors, including:
• Verification of vendor and contractor responsibilities
• Coordination of vendor and contractor activities
• Verification of vendor and contractor performance As the plants are huge in size and complicated also the ready contact with vendors is mandatory. This helps them also to plan the availability of their support team and keep the spares ready. During this phase the performance of these instruments also gets verified hence their representation also is essential.

14. Development of Commissioning Schedule

• Development of commissioning schedule, including:
• Identification of commissioning milestones and deadlines
• Development of commissioning timelines
• Verification of commissioning schedule As part of next immediate activity the commissioning schedule need to be chalked out based on the experiences gained during pre-commissioning. The readiness of all stake holders need to be ensured as immediately after this water trials will start and then final product trials will start.

15. Risk Assessment and Hazard Identification

• Risk assessment and hazard identification, including:
• Identification of potential hazards and risks
• Assessment of risk levels and potential consequences
• Development of mitigation strategies and contingency plans These pre-commissioning activities are critical to ensuring a safe and successful startup of a process plant. They help to identify and mitigate potential risks, ensure that equipment and systems are properly installed and tested, and verify that operators are trained and competent to operate the plant.