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Safe Mechanical completion, Pre-commissioning, Commissioning and startup | Oil & Gas facility


Safe Mechanical completion, Pre-commissioning, Commissioning and startup | Oil & Gas facility
Safe Mechanical completion, Pre-commissioning, Commissioning and startup | Oil & Gas facility

Safe Mechanical completion, Pre-commissioning, Commissioning and startup | Oil & Gas facility

This article provides the systematic approach for commissioning and startup of any new facility, mainly for brownfield.

Meaning of commissioning: Commissioning is the phase in a project when design process fluid or safe fluid is introduced to the systems and sub-systems. In simple word, project construction work is over and special activities started to validate that the equipment, machines, systems and subsystems, other system components are installed, tested and operated in line with project requirement or intent.

For safe, swift and successful plant commissioning, activities are divided into 12 key elements based on any project philosophy.

  1. Review and updating of Project HSE plan
  2. Review of project Risk register
  3. Planning of commissioning process
  4. Mechanical completion
  5. Examination of P&ID
  6. Pre-Commissioning of system, component or equipment
  7. Commissioning
  8. Pre-Startup Safety Review (PSSR)
  9. Plant Startup
  10. Initial operation
  11. Performance test for validating plant intend
  12. Post commissioning

1. Review and updating of Project HSE plan

HSE Plan provides a document to cover the project Health, Safety & Environment management system and contractor must implement during the execution of the project as per agreed conditions. This is dynamic document and must be reviewed at various phases of project right from construction phase to commissioning, startup and operation.

2. Review of project Risk register

Risk register provides the assurance to project team that they have identified all the work-related hazards and risk is managed at ALARP level. This document is continuously reviewed and revised at each phase of project. Before planning the commissioning phase, Risk register must be revised by identifying the new hazards, analyzing the existing controls and assessing the risk. It also provides the information about any further requirement of safe work practices and work procedures.

3. Planning of commissioning process

Planning is the first element to commission of any facility safely and in time. Here clear organizational chart with roles and responsibilities of all members of commissioning team are framed out. Decide all different types of checklists i.e. structure, piping, mechanical, electrical, instrumentation, etc and develop operating manual. Other important procedures are;

Planning of commissioning process
Planning of commissioning process

  • Pre-commissioning procedures viz. air blowing, water flushing, steam blowing,
  • Commissioning procedures for the systems and units.
  • Safety procedures
  • Quality control procedures
  • Security procedures
  • Emergency management plan and Response procedures  

Other than above procedures, Commissioning status progress reports need to be developed to measure commissioning progress. Test records need to be maintained to keep track of all pre commissioning and commissioning activities. Develop a punch list format with a construction department together. Planning of manpower requirement including the pre-commissioning team, the commissioning team, the operating team and the maintenance team.

Planning must be done along with client so that their team should join the commissioning activities on site (Involvement of client engineers/ operators is very important as this is the best opportunity to trained them.). Other agencies may be involved as contractors’ vendors and process engineers.
Ensure advance planning of material requirement. Material like blinds, split pieces, hoses, steam blowing equipment, tool box/ kit, etc my requires during pre-commissioning and commissioning activities.

4. Mechanical completion

Mechanical completion means construction completion and here mainly the construction team is involved but some time commissioning team may be involved for better understanding. In Mechanical completion phase all machines, all equipment and site construction are inspected and tested to validate that the installation is in line with approved drawings, specifications and ready for pre-commissioning or commissioning in safe manner. It also confirms the compliance of project requirement.
As in project, different disciplines are working and therefore mechanical completion may be separated by different disciplines viz. Mechanical, Piping, Electrical, Instrumentation, Automation, Structural integrity, etc.

Mechanical Completion
Mechanical Completion

1)    Mechanical Discipline: Validation for completion and correction of
  • Nameplate, display details at tanks, vessels, rotating equipment and other machines.
  • Internal inspection of tanks and vessels
  • Hydro-static tests of vessels and tanks
  • Dimension control
  • Bolt tension
  • Preservation

Vendor representative must be on site for complicated machines viz. compressors, blowers, pumps.

2)    Piping Discipline: Validation for completion and correction of
  • NDT
  • Pipe supports
  • Confirm that damages during flushing, cleaning and pressure testing are rectified
  • Blowing/ flushing finished
  • Chemical cleaning & drying
  • Preservation
  • Reinstatement
  • Bolt tension
  • Insulation on piping except on flanges and flow coding.

3)    Electrical Discipline: Validation for completion and correction of
  • Electrical panels installation
  • Cable trays and its supports
  • Cabling in tray and cable dressing
  • Bend radius of the cables
  • Connection/ Termination
  • Grounding
  • Megger testing

4)    Instrumentation Discipline: Validation for completion and correction of
  • Instrument panel installation
  • Cable trays and its supports
  • Cabling in tray and cable dressing
  • Bend radius of the cables
  • Connection/ Termination
  • Grounding
  • Instruments
  • MOVs
  • loop checks
  • Tightness test & flushing of tubing

5)    Automation Discipline: Validation for completion and correction of
  • DCS console and its user-friendly installation
  • Central process unit
  • Cabling & tagging
  • Termination
  • Grounding
  • Loop checking

6)    Structural Discipline: Inspection of all supporting structures for
  • Dimensions
  • Integrity
  • Bolt tension

5. Examination of P&IDs

Commissioning engineers are examining the P&ID to validate the system for engineering and construction error after handing over of system or system from construction to commissioning team, here punch points are submitted for rectification.

To perform this stage, ensure latest revision of P&IDs marked with system boundaries, equipment drawings/ datasheet, different type of checklists, national and international standards, hookup drawings and vendor documents for complicated equipment.

Below items should be checked during P&ID examination.
  • All piping, fittings and valves
  • All equipment and machines ie. Motors, pumps, vessels, exchanges, heaters, turbines, compressor, etc along with vendor representative.
  • All instrumentation including nameplate, flow direction, mounting position, temperature range, pressure range, flow and other measurement range.
  • Safety consideration i.e. Whether it is safe installation and Support safe operation too.
  • Operational convenience i.e. Requirement of platform or other safe approach.
  • Maintenance convenience i.e. requirement of monorail/ hoist over motors and pumps.

During P&IDs examination, some additional activities may be carried out like provision of temporary identification tags & signs for piping, valves, machines and equipment.
Any deviations in this process must be marked in punch point list, signed it and submit to construction team and QA/QC engineers. After correction of punch items and confirmation from construction and QA/QC department, joint visit should be done to validate the compliances and closed immediately by signing off.  

6. Pre-Commissioning of system, component or equipment

After finished of mechanical completion i.e. construction completion, Pre-commissioning activities starts to validate the equipment or component is fabricated, installed, cleaned and tested in accordance with a design intend and ready for commissioning. Pre-commissioning activities includes energizing of equipment/ machines, flushing and cleaning, drying, leak testing, running of equipment, running of electrical motors, loading of catalyst in reactor, loading of catalyst in columns, dry run, etc. sometimes pre-commissioning activities are included into mechanical completion.

It also ensures the closing of columns, vessels, drums, tanks, final restoration of systems or subsystems after cleaning, air tightness or leak testing of systems, lubricants application, etc.  
Sometimes pre-commissioning includes installation of filters, packing of distillation columns, molecular sieve beds, refractory dry out, instrument/ electrical and motor loop testing etc. All the findings/deviations must be noted in punch list.


Pre-commissioning activities should be prioritized & as per approved pre-commissioning procedures viz.
  • Procedure for necessary spectacular blind installation
  • Procedure for field non-return valve internal installation
  • Procedure for checking refractory lining installation and checking of mechanical interlock.
  • Procedure for checking of distillation or scrubbing columns packing.
  • Procedure for catalyst loading in reactor with installation of filter
  •  Procedure for air blowing, steam blowing, etc.
  • Procedure for water flushing
  • Procedure for chemical cleaning
  • Procedure for tightness test
  • Procedure for cooling water
  • Procedure for mechanical test run of pumps, etc

Below sequence is recommended for pre-commissioning activities based on its priorities.
  • Power and control system i.e. electrical substations, Building power, etc
  • DCS and PLC systems and instrumentation
  • Row water and firefighting systems
  • Wastewater treatment systems
  • Oil, cleaning & chemical sewer systems and neutralization pits
  • Service water, potable water and cooling water systems
  • Instrument air, plant air and air regeneration systems
  • Water treatment systems.
  • De-mineralisation plant
  • Boiler water system
  • The nitrogen system
  • Flare system
  • Plant safety equipment and fire and gas detection
  • Fuel gas and fuel oil system
  • Slop systems
  • Flushing oil system
  • Boiler systems with steam and condensate networks
  • Aromatics and caustic drain systems
  • Feed and product storage systems
  • Product and feed systems
  • Amine treatment section
  • All the process systems, etc

Pre-commissioning checklists must be developed for different types of machines, equipment and systems to record the result of inspection and to confirm readiness for commissioning. All these checklists should be witnessed by the client, Project Management Control (PMC) , the licencor, etc.  Test records must be maintained for all system checking, preparation activities and other number of tasks like chemical cleaning, drying, air tightness test, loading of catalyst, blind list status and the performance indicators. Similarly, records for QA/QC documentation, system punch list associated with various pre-commissioning activities viz piping, stationary equipment, rotating equipment, instrumentation pre-commissioning activities and tightness tests should be maintained. This will help to track the planned vs completion and the remaining tasks which must be done. Status of the punch list report for outstanding punch points must be monitored.

Vendor specialists should be on site for major items of rotating machinery, major utility systems, special electrical & instrument control equipment, package units which have been assembled by someone at site shipped by a vendor, the licensor do the final inspection of critical equipment installation as well as  the supervision of catalyst and chemical loading.
After completing the Pre-commissioning check with validating all punch points, facility will be ready for commissioning.  

7. Commissioning

In a project, after pre-commissioning, next phase is commissioning where design process fluids or safe fluid are introduced to the systems and subsystems.  Commissioning is the stage where project finished its construction phase and planned to entire in commercial operation stage. In this stage, it is validated that each system or subsystem is fabricated, installed, cleaned and tested as per design intend and the systems are ready for startup. Some time it is called as cold and hot commissioning.  Cold commissioning is of two type i.e. dry commissioning and wet commissioning.

Dry commissioning, Wet Commissioning, Hot Commissioning, Cold Commissioning
Types of Commissioning

  • Dry commissioning:  means tests and procedures that are conducted without solvents or process fluids. Eg. interlock and emergency shutdown tests or control system sequence checks, etc
  • Wet commissioning: means water/ safe fluid or a solvent has been introduced into the systems or subsystems for testing purpose to simulate the operating scenarios to understand the system's behavior. Eg. running of pumps in closed loops or interlock and emergency shutdown tests.
  • Hot commissioning: means design process fluids are introduced to the systems and subsystems and the activity is similar to wet commissioning activities like running pumps with a closed loop.

For safe commissioning of facility, ensure safety measures like permit to work system.  If the new facility is adjacent to existing one and employees/ operators would be same, then existing PTW should be used otherwise it should be modified adequately.

Construction area might be fenced to separate it from existing operational facility then security and access control must be ensured. Emergency response procedures must be made aware to all commissioning team and other related workforce. Final leak testing, final drying, final purging and energizing must be completed in safe manner. For initiating systems and subsystems filling with process media, operation of systems and subsystems, completion of system, etc lot of documentation is required in commissioning phase. Therefore, commissioning sequence must be followed for commissioning of the facilities system by system and unit-by-unit basis and it should be backwards approach.  Below backward sequence is suggested;

  • Control systems DCS /PLC
  • Utilities i.e. air, nitrogen, water, steam etc.
  • Product storage tank systems
  • Loading systems
  • Process units ie. reactor, furnace, exchangers, vessels, columns, etc
  • Raw material feeds
  • Raw materials storage, etc

For safe commissioning, whatever commissioning procedures finalized in planning stage, these all procedures must be followed. Eg.
  • Commissioning procedures for utilities and services
  • Commissioning procedure for uses of water or a solvent in each system
  • Commissioning procedure for introducing process fluid in each system
  • Procedure for Interfacing (operation and maintenance work with commissioning work)
  • Product quality control procedure
  • Procedure for laboratory analyzes for the new facilities
  • Procedure for production planning.  

on operation of the new facilities must be integrated during the commissioning startup and initial operation phase this commences with first requirements for fuel gas and other things from the existing plant for boilers startup and dry out through initial feed stock transfer and final product storage blending and shipping.

maintenance support must be ensured by company to monitor pump temperature and vibration during commissioning. All commissioning activities by contractors, vendor specialists, etc must be carried out under the supervision of commissioning team and the licensor. Process licensor may supervise the commissioning activities for important and critical systems and must provide technical assistance during all stages of commissioning. Process operating parameters and conditions will be advised by process licenses, process engineers.

8. Pre-Startup Safety Review (PSSR)

The purpose of Pre-Startup Safety Review (PSSR) is to ensure that new/modified facility is ready for safe and continuous operation. The PSSR must confirm the following, prior to the introduction of process fluids to a process/systems/subsystem.
  • Construction and equipment meet design specifications.
  • Safety, operation, maintenance and emergency procedures are present and adequate.
  • For new/modified facilities, a MOC procedure had been followed, and all HAZOP recommendations have been implemented before startup.
  • Training of each employees involved in operating a process has been completed.

PSSR is the last step in commissioning process and managed by commissioning manager and the client commissioning team jointly.  Vendors and licensor may join PSSR. Completion of PSSR and compliance of all its punch points will validate the facility/system for its readiness and to commence safe startup.

9. Plant Startup

Plant startup is the phase where the entire plant, all systems and subsystems are taken into operation, process fluids are introduced, and process conditions are established with intent of making products.  For continuous startup activities, employees must be assigned in work shift duties so that client, the contractor and some vendors and licensor should be available 24x7. Shift logbook with clear instructions for its filling should be specified before starting the plant.

Once again assure the compliance of punch points of PSSR and ensure the pre-startup checklist by tick mark on it step by step. Checks are;
  • Whether all utilities available for safe startup
  • Whether feed is available
  • Whether enough product storage available
  • Whether all involved startup team members are well aware about different startup procedures
    • Pipe and equipment purging procedure
    • Pipe and equipment evacuation procedure
    • Procedure for Initial introduction of feed and chemicals
    • Procedure for initial heating or cooling
    • Procedure for loading catalyst or other media into initial conditions
    • Startup sequence with normal operating data
    • Procedure for plant operating under normal conditions
    • Procedures for shutdown
    • Procedures for emergency shutdown
    • Procedure for simultaneous operation

Ensure implementation of proper interfaces, i.e. operations and maintenance, product quality control by company with quality control laboratory analyzes, production planning by company and emergency response for contractors, security and safety together by company and contractor. Similarly, maintenance support by the company and on duty technical support managed by the contractor and the licensure. Where required, the process licensor supervise the start-up of relevant systems and provide technical assistance. Process operating parameters and conditions will be advised by process licensor and process engineers.
All process parameters and data must be maintained which would be most useful for next phase i.e initial operation phase.  After finished of successful startup, plant is ready for initial operation.

10. Initial operation

Initial operation means the entire plant is running in continuous operation, fine-tuned and prepared for the performance test.  Most important things are fine tuning of control loops, complete process and testing of operational limits. Check the limit that the emergency shutdown starts and observe that emergency shutdown is working well. Maintain all important data related to equipment, relevant processed data and as well performance data. This will help for next stage i.e. performance tests.
Still successful completion of initial operation stage, licensor involvement may be there as per requirement for relevant systems to provide technical assistance and may advise for process operating parameters and conditions.

11. Performance test for validating plant intend

Performance testing validates the plant that it is operating according to design intend. Performance testing includes facility operation and performing numbers of specified activities, demonstrations and tests to measure the new plant and equipment against the approved project design and specified parameters.
Time duration for performance test is varies from plant to plant and as well type of industry to industry.  A simple water treatment plant may finish a performance test within a 24 hours’ time period or 48 or 72 hours but other large plants or complicated plants like oil refining units with numbers of trains may takes a month or several months because each trains will be run step by step then all trains should be run simultaneously/ together. Shift duties must be assured for continuous monitoring and observing the performance trend. If at certain period, performance test gets fail, then licenser intervention is required.  It is good practice to have/ maintain separate logbook by the client and the contractor and to tally with each other to detect any error. Performance tests procedures must be ensured by both the party and follow the same agreed sequence.
During performance test below activity should be ensured by both client and contractor;
  • Quality control
  • Production planning
  • Emergency response
  • Security and safety together
  • Maintenance and technical support
  • Supervision and monitoring of process parameter.
  • Recording of all readings
  • Install an additional measurement device if existing is not adequate.
  • Comparison of process data with specifications
  • Maintain shift book
  • Monitor the DCS system
  • Sampling of products and lab analysis
  • Analysis and assessment of performance test parameters

If all performance parameters are matching with project intended parameters, then we will have a final acceptance. Generally, performance test data requires about two to three weeks for evaluation by the client contractors and the licenser.  If it is satisfactory then final acceptance i.e. cares, and custody is transferred from contractor to the client and this is called as project plant hand over. Satisfactory result of performance test may result to official handover of the plant and proves that commissioning team has fulfilled the obligations. But there may be minor punch list which is to be attached with final acceptance certificate.

12. Post commissioning

Post commissioning is the phase after handing over of plant to the client. Handing over to client means final acceptance certificate is now signed by client and operations assistance is not needed anymore. Outstanding punch points are solved, and some adjustments, modifications and fault corrections being completed. Also, some routine maintenance checks and performance findings being evaluated and monitored for process equipment and items covered under warranty. Problems and operating data is being collected and evaluated to ensure consistent plant operations. Here contractor commissioning team who was involved in commissioning process will stay and responsible for solving the outstanding punch points and solving any troubleshooting. As this commissioning peoples are having experience of this particular plant, they know everything, where to go for which particular problem, what will be solution for particular deviations, etc. After few weeks or months as per project agreement, one or two persons may stay along with client and they will be responsible and coordinate for production planning, operations, maintenance, product quality control, emergency response, etc. Licensor may also stay there as per project agreement for technical guidance on process parameters.


Safe commissioning of any new facility or modified facility can be achieved successfully by proper commissioning planning, well organized team framework, proper coordination between client, contractor, vendors and licensor, ensuring availability of Manual and procedures, security and safety system, well developed data entry formats and checklists, logbook and other records, etc. Compliance of Safety management system and proper coordination between different disciplines are the key areas for safe and successful commissioning of project, where operational facility is adjacent to new project.

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  1. I think this article will fully complement you. Please continue publishing helpful topics like this. Regards, from Asset Management Software

    Aged Care CMMS Software

    Pre-Start Checklist

  2. Thanks you for appreciation

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