While the benefits are numerous, so are the challenges, especially compared to alarm rationalization on an existing (brownfield) system, where the hardest part is determining whether you are going to start “from where you are” (bottoms up) or start from scratch (tops down). Alarm rationalization is done before the configuration of the control system in some greenfield applications, however in others it is done in parallel.
As shown in Figure 1, there are many sources for creating a master alarm database for a greenfield (a brownfield typically has one - the existing control system configuration). These design inputs (like I/O Lists, P&IDs, and HAZOPs) are often evolving over time as the design matures, which makes management of change uber-critical.
Here are some tips to consider before you launch into rationalization of a greenfield system:
- Don’t begin rationalization too early. Certain design information (completed PHAs, I/O Ranges, Tag descriptions) should be well established before beginning
- Select a master alarm database tool that allows you to bring in information piecemeal from all the different design sources and identify changes
- Make sure you have a well-thought out alarm philosophy document in place before beginning
- Select an alarm rationalization tool that will allow you to easily transfer the rationalized settings to the control system (after it is configured) so that you don’t have to do it manually