Commissioning is an important stage of development for any plant or facility. This is a set of tests, checking and activities to convert newly built facilities to an operating plant capable of commercial operation at full capacity. The commissioning is usually performed in four phases: pre-commissioning, core commissioning, startup and post-commissioning.
Pre-commissioning examines the facets that address the installation, cleaning, checking out and final preparations of the installed equipment, machineries and facilities. The operation of each item, machine or equipment, which then combined and operated as systems and integrated facilities, is usually categorized as core commissioning. Startup is the start of the actual operation of an integrated plant. In other words, this is the first time the integrated plant is put in the commercial operation. The final stage of the commissioning and the one most neglected is post-commissioning, which consists of final troubleshooting, handover to operation, commissioning report, as-commissioned documents delivery and closeout.
This article discusses commissioning of fluid movement facilities. The focus is on practical guidelines to help commissioning engineers and site experts resolve issues and facilitate the progress of commissioning of fluid movement units and facilities.
Preparation and pre-commissioning
The commissioning team and all required preparations should be organized before the commissioning work begins. The commissioning team should ideally familiarize themselves with the equipment, systems and machineries in the plant, the expected performance of different units, operational details and parameters, concerns and highlights of the plant. The last activities are usually achieved by a series of meetings with different parties, such as the construction team, client and operation team.
Pre-commissioning activities usually start when the unit or system achieves mechanical completion. However, pre-commissioning activities frequently overlap mechanical completion activities, for instance, a unit can be under pre-commissioning and neighbor units still be under construction. For this reason, a plant can be separated into easily manageable pre-commissioning packages. Each package would be pre-commissioned as a whole, and isolations at the boundaries of the system package will be maintained until the completion of pre-commissioning activities. Pre-commissioning activities include: checking for design conformity, checking the status of electrical, mechanical and instrument installations, running-in of equipment, flushing, cleaning and drying.
Pre-commissioning is the stage of thorough site inspection of every item or device. A pending list should be prepared for each pre-commissioning package as the result of such vast and comprehensive site inspection and its pending items should be resolved as soon as achievable.
Bolts and similar tightening parts should be tightened as required; this is a common pending item in pending lists. Wiring in general and electrical/instrument wiring connections need great care. All switches, instruments, indicators and other devices should be properly installed and be prepared to be qualified for further stages such as a loop test.
Grounding is sometimes missed, and this is a common fault in facilities. The grounding status of any equipment or machinery should be checked, and the grounding resistance should be measured and verified. All tubing and networks of piping and conduits should be checked and verified. Examples are centralized lubricating systems; such a system should be thoroughly checked. There should be no leakage, deformation or damage, and the entire network should be complete and work properly. There should be no blockage as well.
Planning is the key for success in commissioning. Proper planning and sequencing different construction, completion, pre-commissioning and commissioning tasks for different units and packages are extremely important for proper transition from erection and installation phase to the commercial operation. An estimate on the number of workers, technicians and supervisors should be provided for each stage of the commissioning as part of the planning. For packages such as fluid machinery packages, usually a part of the commissioning work, mostly pre-commissioning works such as flushing and cleaning, are implemented in the manufacturer’s shop before the delivery to the job site. This is helpful in the commissioning of fluid movement packages.
Safety, documentation and records
Safety precautions are important in commissioning. Proper risk assessments should be done before any pre-commissioning and commissioning step. There are many different risks and hazards in many tasks and activities of commissioning. For instance, in many steps and stages of commissioning, there is a risk of fire. Therefore, the job for firefighting systems should be commissioned and started before any risky tasks, or temporary firefighting equipment should be provided.
Commissioning is a phase of the project where all problems and issues in previous stages such as design and construction are surfaced. Often, a set of deviations might be accepted to facilitate the commissioning. However, no deviation should be accepted on matters related to safety, reliability or operational flexibility.
Documents and records are an important part of the commissioning, as any check, inspection or activity should be supported by a proper record or signed form. The requirements of commissioning phases should be followed, and this compliance along with all measured data should be recorded. Various technical parameters and measurements should be recorded, and proper forms or reports should be filled and signed upon completion of each stage of commissioning. Many forms and templates are need in the commissioning. Every step or stage in the four major phases of commissioning, namely, pre-commissioning, core commissioning, startup and post-commissioning, needs a dedicated form.
Troubleshooting is a major task in the commissioning. Complete troubleshooting guides should be prepared in advance as a part of commissioning procedure for any items, machinery, equipment or device in the plant to help identify and correct any malfunctions that might occur.
All required items, lubrication, chemicals, tools, spare parts, bit and pieces for the commissioning should be ready in advance. For example, all necessary lubricants required during commissioning should be supplied well in advance, as it is unacceptable to delay commissioning for small shortages or deficiencies. The quantity and grade of lubrication oil in each machinery should be the proper one. Wrong types and grades of oil were frequently used in previous commissioning exercises on different machines and equipment, which caused problems. Also, all required operational data should be supplied in advanced such as alarm descriptions, alarm set points and initial settings for commissioning.
A critical task during commissioning is the handover. Handover procedure(s) complete with details for each handover are needed. There are different types of handovers, for example, the handover from construction team to commissioning team. This is the official start of the pre-commissioning. Another is the handover from the commissioning to operation.
Core commissioning
The commissioning of a typical unit or package is divided into three phases: step-by-step or item-by-item commissioning, no-load commissioning and loaded commissioning. The step-by-step commissioning or item-by-item commissioning should be done per a proper sequence. Each item, equipment and machinery should first be verified, tested and operated individually. In other words, step-by-step commissioning means separate commissioning for each mechanism, device or equipment, and there is no interlocking between various mechanisms or items. After completion of step-by-step commissioning, a step-by-step test for various mechanisms is conducted on the control system. Every mechanism, device or equipment should run for at least 20 minutes separately. Critical mechanisms, machines or devices should be run for more than 30 minutes individually. The operation in the full operating range, for instance, speed range (minimum speed to maximum speed) and complete movement coverage should be fully tested and verified at least three or four times.
Thorough visual inspection should be conducted to make sure there is no defect, obvious deformation, crack, weld joint problems, loose bolt connection, etc. A machine or equipment should be started, and then various modes of operation — such as starting and stopping tests, full range of part load and emergency trips — should be conducted. It should be checked to ensure all limit devices, sensors and instruments are sensitive enough and reliable. Also, safety and limiting systems such as brakes should work reliably. Electric motors have been widely used in plants, facilities and packages. A motor solo test should be done for all motors on site. The purpose of this test is to verify the motor operational characteristic such as vibration, temperature and noise.
After completion of the step-by-step test, a type of system test and operation for individual systems — each consisting of items and machines — should be conducted. This is often a manual test or manual operation in the first step. After that, when confidence is gained, a system or a combination of some systems may be tested and operated using the control system. This operation is usually useful to test the interlocking protection of various mechanisms and devices. After this stage, the integrated facility is commissioned. Within this, complete interlocking protections between various different mechanisms, subsystems and devices should be checked and verified. The purpose of the interlock and trip test is to verify that each system protection control logic and loop such as alarm, trip and associated changeover work properly. This test is performed through the simulation of the control system (PLC, DCS, etc.), and the result should be verified and recorded. The test procedure, architecture and details should be per the latest control logic.
For load test, it is required that all processes, systems and mechanisms become stable and reliable, the motor’s currents should be normal and temperature rise of the bearing housing should also be in the normal range, say, as an indication, no more than 40°C or 50°C. The highest bearing temperature should not exceed a certain level (say, 75°C to 85°C), and there should be no leakage in the system, no permanent deformation or damage or no loose connection. During heavy-load test, the motor’s current should be recorded and compared with the rated values.
There are two types of defects, issues and problems during the commissioning. In case of minor defects or problem, these would be listed in a pending list and can be rectified later, before startup. Otherwise, if the problem, issue or defect is a major one or affects the performance, the problem should be rectified first.
Startup and post-commissioning
Startup is when the commissioned and integrated plant is put in commercial operation for the first time. This should be done per a complete set of operating procedures. Therefore, these operating procedures should be received, verified and approved before the commissioning.
A performance test is usually included in the post-commissioning time. A comprehensive capacity test is most often needed as well to verify that the capacity of the actual facility is as specified in a long-run test. A dedicated capacity test should be carried out on site to verify intended capacity range and sustained production at peak capacity. It can be part of the performance test, but dedicated procedure is needed. A comprehensive reliability run test is also needed. It should be verified that the reliability and availability of the actual plant or facility is as specified and suitable in a long operation run. As a very rough indication, the availability of modern plants, packages and facilities is typically above 97% or 98%.
Post-commissioning tasks and activities are often overlooked. The post commissioning time is a few initial weeks of the commercial operation when the commissioning team work beside the operation team to overcome challenges during the initial operation period and to complete post-commissioning tasks. Too often, a plant or facility faces different sets of difficulties and problems in first weeks of operation. Troubleshooting in this time is usually done by the commissioning team, as the operation team is often busy with their operational tasks and handovers.
A comprehensive commissioning report is needed to detail all tasks performed during all phases of commissioning; this should ideally cover all problems and challenges, solutions and resolutions and lesson learned during the entire commissioning process. The preparation and delivery of as-commissioned documents, which are plant documents marked with updates, modifications and notes of commissioning, should be done with great care.
A high-quality as-commissioned package is a good indication of an excellent commissioning. The last steps are the handover to the normal operation team and the closeout.
Amin Almasi is a lead mechanical engineer in Australia. He is a chartered professional engineer of Engineers Australia (MIEAust CPEng – Mechanical) and IMechE (CEng MIMechE) in addition to a M.Sc. and B.Sc. in mechanical engineering and RPEQ (Registered Professional Engineer in Queensland). He specializes in mechanical equipment and machineries including centrifugal, screw and reciprocating compressors, gas turbines, steam turbines, engines, pumps, condition monitoring, reliability, as well as fire protection, power generation, water treatment, material handling and others. Almasi is an active member of Engineers Australia, IMechE, ASME and SPE. He has authored more than 150 papers and articles dealing with rotating equipment, condition monitoring, fire protection, power generation, water treatment, material handling and reliability. He can be reached at [email protected].
