Process plant commissioning

The transition from construction to operation is commissioning and startup. Process plant commissioning includes activities such as cleaning, flushing, verification, leak testing, performance evaluation and functional testing that are essential to put a newly installed plant or facility into routine operation.

Since commissioning is the last important stage before commissioning, there is a risk that commissioning may be under great time pressure or even that some delayed commissioning activities may continue after the initial commissioning of the plant.

Special efforts are needed to ensure safety and reliability during commissioning. Since commissioning, startup and shutdown have been responsible for many accidents, failures and other problems, these activities deserve special attention. This article discusses commissioning, including pre-commissioning, core commissioning, startup and post-commissioning.

General notes on commissioning

Before a plant or facility is handed over for normal operation, it must be inspected, checked, cleaned, flushed, verified and tested. This process is called commissioning, and it involves both the contractor and the facility operator.

Overall commissioning includes mechanical completion, leak testing, cleaning, flushing, preliminary acceptance, pre-commissioning, initial commissioning and post-commissioning. Careful planning is required for commissioning and startup. The integration of different systems, especially control systems with other systems, must be seamless. This requires a large number of verifications, checks, and tests under realistic conditions.

Economies of scale have led to a rapid increase in processing plant production, increasing the number of items and tools per plant. Complex automatic control systems are being installed to reduce the possibility of misoperation and consequent damage to plant and facilities.

Added to this are extensive and complex condition monitoring systems, widely used in modern processing plants. Commissioning of technologically advanced and computer-controlled plants and facilities usually requires a radical and sophisticated approach and highly competent teams.

Due to the high performance of modern plants and units, there is less room for error in design, construction, operation and commissioning. This makes the installation more susceptible to unforeseen phenomena or errors. This manifests itself in many operational incidents, which cause heavy financial losses to operating companies. In many modern processing plants, there is practically no margin for error or failure at various stages of commissioning.

Pre-commissioning

The pre-commissioning stage often includes many activities, such as installation; inspection of equipment, piping and machinery; checking units and facilities against designs, such as the piping and instrumentation diagram (P&ID), flushing and cleaning, pressure testing, function testing, simulations and more.

At this stage, the operation of all controllers and motorized valves should be checked. All valves, including relief valves, should be tested and verified. Important equipment should also be thoroughly inspected, verified and finally closed in the presence of the commissioning team. Initial measurements of critical clearances should be made for later comparison and verification.

For equipment inspection, it is helpful to ask maintenance engineer(s) to attend or even participate in commissioning activities to inspect and test all equipment and rotating machinery, including electrical or mechanical machinery. After all, maintenance personnel must take care of these machines and equipment during operation, and the commissioning phase is the best opportunity to begin this task.

Commissioning & Startup

The commissioning phase includes daily involvement in making important decisions on site. There are significant challenges and elaborations in this daily involvement when it comes to risk-taking, accepted deviations, financial control and plant changes.

For each medium-sized area of a plant, a team with a number of people is needed for the core commissioning phase to provide continuous coverage during the core commissioning and start-up period.

Staff engineers who were previously at the plant for construction or pre-commissioning may be part of this core team. At least half of the team, say two or three, should have good operational experience. In addition, the team should have specialized knowledge in design, maintenance and operational analysis. An ideal team consists of a commissioning area manager, a commissioning process/operational engineer, a commissioning mechanical engineer, an operations/maintenance engineer, and a commissioning electrical engineer and instrumentation and control (I&C) engineer.

It is difficult to remove team members with operational experience from their normal operational team - every effort should be made to make their stay as short as possible. The team should be led by a senior manager (area commissioning manager) who can advise on changes and operational decisions in a situation where the line of management and authority can be much more complex than in a normal environment.

Commissioning is a high-risk undertaking in which personnel, facilities, the plant and materials are at risk. The responsibility and authority of engineers and experts involved in commissioning must be clear. There should be no doubt about where responsibility lies. The correctness of key decisions and the speed with which they are carried out have a major impact on subsequent progress.

There is often an interaction between the general situation and commissioning. Sometimes this occurs in an atmosphere of commercial calm; there is then no rush and activities proceed in a normal sequence. Usually, however, this is not the case. For many plants and installations, much time is wasted during the design and initial stages of construction, while the output of the plant is tied to an absolute deadline. In this situation, installation and construction is rushed, supervision is stretched by excessive labor accumulation, and commissioning may occur while part of the plant is still being completed. The result is a commissioning atmosphere with limited time and financial freedom, combined with significant technical problems, many deviations awaiting decisions and elements of calculated risk-taking.

Most equipment and components are first subjected to designed operating conditions during start-up, when the unit or facility is first put into operation. Failures in equipment, components, or facilities at this time can result in major revenue losses to the operator, so it is advisable to subject components to designed operating conditions with great care. A correct start-up sequence and procedure are necessary and must be followed with the utmost care and diligence.

Each machine or equipment requires a specific set of spare parts for commissioning and startup. Large quantities of spare parts must be provided for this phase so that commissioning and startup are not delayed by a lack of spare parts or tools. All too often, spare parts consumption is abnormally high during startup due to rapid deterioration of unsuitable equipment or parts, abnormal loading of equipment due to design deficiencies, and faulty operation for various reasons.

Startup & post commissioning

The first few days and weeks of commissioning is a critical and challenging period that requires a lot of attention. The commissioning team continues its work and activities during this period. The commissioning period should not end until the plant is generally operating satisfactorily, although the senior members and experts of the commissioning team may be gradually withdrawn after the first few weeks. It is a fact that plants and installations often face challenges and difficulties in the first period of operation. The speed of problem solving and development will decrease once the commissioning team is disbanded.

The goal during the initial operating period is to facilitate operation, remove bottlenecks, reduce costs and improve quality. The supply of additional items and equipment will also be discussed and decided at this stage by a committee consisting of various parties such as commissioning team, operations team, maintenance team, etc.

Special attention should be paid to the deterioration of mechanical conditions affecting the operation of the plant after commissioning. Factors and parameters such as fouling of the heat transfer surface, reduction of the pumping speed, deterioration of the vacuum, etc., if reported, should be properly investigated by the commissioning team that has just put the plant into operation.

A special area for cost reduction involves some mitigation measures such as improvements or even replacement of maintenance-sensitive equipment. equipment. Financial situations must be evaluated on a case-by-case basis, and an important factor in such studies is the interruption of operations (production) and the associated financial losses.

Proper transfer of documents, knowledge, procedures and experiences after commissioning to operation and maintenance teams is important for ultimate success. Great attention should be paid not only to the transfer of operational routines, but also of control and maintenance procedures.

It is helpful to train all customer personnel in addition to the operations team. When transferring maintenance experiences and procedures, keep in mind differences in maintenance concepts between different teams and companies.