Handbook for Process Safety in Laboratories and Pilot Plants

14 Overpressure Prevention and Protection

Equipment overpressure can lead to consequences such as personnel injury, environmental harm and damage to facilities as described in Section 10.1. This chapter provides an overview of overpressure prevention and protection, including design, safeguards, and practices. References to the literature are provided for detailed information on design of overpressure protection equipment and systems. More information on automated shutdowns may be found in Chapter 16.

14.1 Pressure Protection for Equipment

Providing overpressure protection is typically done in one of three ways:

• Design the system to accommodate the highest possible pressure
• Provide electronic shut down or limiting further increase by appropriate response action
• Provide mechanical relief device(s)

14.1.1 Designing to Contain Highest Possible Pressure

Providing overpressure protection by design is an inherently safer approach that is often possible in LAPPs due to the small scale of many lab units and some pilot plant equipment. Designing for the highest pressure may avoid the need for other types of relief devices, it eliminates the potential for premature releases and reduces maintenance costs. However, it is important to fully analyze all the potential failure modes which might occur. Factors other than pressure can still lead to a failure of the reactor:

• reactor is overheated, resulting in a lower pressure rating
• reactor is corroded, resulting in a weakened spot
• an ...