(164b) Making Inherently Safer Design (ISD) a Vibrant Part of Corporate Risk Management or “How to Do Effective ‘Safer Technology Alternatives Assessments (STAA) “

Recently, five very experienced process safety engineers met to compare notes on the best ways to incorporate inherently safer design (ISD) into new and existing plants. It’s an important topic, especially now that EPA has mandated that many plants governed by its RMP regulation begin doing safer technology alternatives analyses (STAA) no later than May of 2027. We discussed how and when to do an STAA and who should be involved. As we went over our numerous “war stories” about successful adoption of inherently safer technologies at many different companies - as well as a few “tick the box” exercises we’ve come across that didn’t add much value - patterns began to emerge. This paper will explain the patterns and what we consider to be the most effective of the possible processes to conduct ISD/STAA’s.[1]

We will use a lifecycle approach to discuss how to identify opportunities, with real-world examples from each phase of the lifecycle:

1. Chemistry (in R&D)
2. Process Design (in Project Engineering)
3. Process Engineering (in project, as well as during the rest of the plant’s life)
4. Demolition of abandoned piping/equipment right after you stop using it. (MOC and implications for PHA revalidation)

We will point out how ISD reviews can be conducted "upstream" in Phase 1 of the project lifecycle or even before Phase 1 in partnership with R&D. The paper will review specific practical issues and lessons learned along the way, such as selecting effective ISD chemistries early on, as well as how to document ISD “safeguard features” within process hazards analyses so they will not be forgotten – and possibly removed - over the years.

But what to do once the plant has been built? For many years, our industry has managed its process safety hazards through a robust process of hazard identification. We advocate the use of a semi-quantitative risk matrix rating system. As long-time practitioners in process safety, most of our collective efforts have followed a familiar path. Identify a hazard, estimate its potential consequences, estimate the initiating event frequency, then reduce that frequency by adding on safeguards until we reach the company's tolerable risk level. But there are two dimensions in a risk matrix. The other key aspect of risk is the consequence of a scenario. If we could reduce the consequence, then we may not need so many safeguard layers.

Perhaps most importantly, we’ll discuss how companies should focus their efforts on the most important hazards (hint: highest potential consequences as well as higher-than-normal initiating event frequencies).

This paper will describe a number of practical applications of ISD within operating facilities, where consequences of identified scenarios were reduced, from reducing the deadhead pressures from pumps to substituting combustible solvents to replace flammable ones. It will describe efforts to institutionalize the ISD thought process, and to drive from a) the application of ISD in small changes later in the design process towards b) the application of ISD back in the research and development phase. It will discuss why it's best to focus ISD efforts on new projects – in line with the strategy suggested by Trevor Kletz (who first coined the phrase “ISD”) many years ago. It will point out the practical steps such including experienced engineers from sister plants, as well as PHA facilitators with an understanding of options to apply ISD within existing facilities.

[1] For simplicity this paper will use the term ISD to refer to inherently safer technology (IST), STAA and ISD.