When considering replacing your existing control system with a new control system it is important to plan the project up front. At Emerson on a typical Greenfield project, we would write a Project Execution Strategy. This is pretty standard because the implementation method of Greenfield projects is well understood and reasonably consistent between projects.
For a Brownfield project, this is generally not the case. The Project Execution Strategy (or Migration strategy when it is a migration) for a Brownfield project is often very specific to the associated plant or platform.
A key decision with Brownfield projects, which requires factoring into the plan, is how to cut over operations from the old control system to the new one. For example, you may wish to shut down production for a period of time long enough to perform a full cut over. That may not be a luxury you can afford so you may need to cut over one unit at a time whilst production is reduced—or a multitude of other options.
As you can appreciate from the above point alone, planning the replacement of your existing control system is a complex activity, which should only be completed through collaboration with experienced engineers and consultants who specialise in this type of a project. A robust Brownfield Project Execution strategy is highly dependent on the quality of information available to the author.
I would therefore like to make some suggestions on what information you, as a customer, should make available to your engineer or consultant when he or she is planning to write the strategy. These are my suggestions:
- Standards which you would like the project to consider, for example quality standards or internal technical standards
- An export of your existing control system configuration
- Copies of the original specifications provided with your control system (updated to the current status if possible)
- Photos of the internals of all the control system cabinets which are clearly identified based on location
- Details of any serial packages or interfaces to higher level systems
- Floor plans of the rooms which contain control equipment and floor plans of rooms which may be used in the future to locate equipment
- A description of the room ambient conditions where you plan to locate the new control system equipment. For example, is it humid or does it reach high temperatures?
- Your current thoughts on shutdowns. For example, how long you are prepared to shut down for, or if you can shut down most of the plant
- The timelines you would like for the project and time lengths of typical plant shutdowns
- Details of the spare parts you hold for your existing control system
- Photos of the operators control room and desk
- Details of any gateways you use or barriers which may need to be replaced or interfaced to
- I/O counts for the control system and if part of the scope, safety systems
- Network diagram of the existing control system
- Cabinet general arrangement drawings
- Power distribution details
- Identification of equipment you are concerned about the reliability of any other risks to the project which you can foresee
- Mapping lists for serial packages
- A process overview of the plant
- A description of the level of expertise within your business to adjust and maintain the existing control system
- A list of requirements for the new control system
- A description of any other projects or significant activities which may be happening at the same time as the control system replacement project
- Training requirements, if known, on the new control system
- Details of any unusual instruments which the system will need to interface to
- Details of any equipment or instruments which are referenced in the control system software and hardware but are no longer in use
I imagine that there are many further inputs, which a customer could provide that I have not listed here. If you have any suggested information please feel free to inform the readers by adding it as a comment. Remember the better the quality of input information the more concise and accurate the execution strategy will be and the easier it will be for you, the customer, to make an informed decision on how to proceed.
Please feel free to let me know your thoughts in the comments section below.