Top Ten Questions to Ask about Pressure Relief Systems in a Process Hazard Analysis
- Type: Conference Presentation
- Conference Type: AIChE Spring Meeting and Global Congress on Process Safety
- Presentation Date: August 20, 2020
- Duration: 20 minutes
- Skill Level: Intermediate
- PDHs: 0.40
It is crucial for Process Hazard Analysis (PHA) teams to be aware that the mere presence of a pressure relief device does not necessarily constitute a valid safeguard against all overpressure scenarios for the protected system. This paper will present the following list of the ten most important questions for a PHA team to ask when considering pressure relief systems as safeguards.
- Are set pressures appropriate for each protected system?
- The paper will discuss appropriate relief device set pressures with respect to equipment Maximum Allowable Working Pressure (MAWP) and overall system pressure profiles.
- Are pressure relief systems adequately sized for each applicable scenario?
- The paper will discuss simple screening techniques to identify obviously undersized relief devices and conservative assumptions to employ when these techniques do not apply.
- Are relief devices of appropriate type present for each applicable scenario?
- The paper will discuss examples of appropriate and inappropriate device types for example overpressure scenarios.
- Is the physical installation of pressure relief devices in compliance with applicable codes and standards?
- The paper will discuss straightforward approaches to identifying non-compliant physical installations based on Process Safety Information (PSI).
- Are pressure relief system discharge locations appropriate for each protected system?
- The paper will present examples of appropriate and inappropriate discharge locations and methods for documenting relief to an unsafe location in a PHA.
- Have pressure relief systems been properly considered as part of the facility Management of Change (MOC) program?
- The paper will discuss examples of process changes that can have significant effects on the design of pressure relief systems.
- Have any instances of pressure relief devices activating been properly identified and investigated as near misses?
- The paper will emphasize the importance of tracking relief events as near misses.
- Have the sitewide and offsite effects of global overpressure scenarios been properly considered?
- The paper will provide examples of global overpressure scenarios.
- Has the malfunction of pressure relief devices been properly considered?
- The paper will provide examples of potential PHA consequences due to spurious activation of pressure relief systems.
- Has the potential for vacuum relief, including potential air ingress through a vacuum relief device, been properly considered?
- The paper will discuss examples of vacuum relief scenarios for pressure vessels and potential consequences of air ingress via vacuum relief devices.
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