Considerations for inadvertent valve opening are similar to the inlet control valve failure; however, the calculation methodologies for pipe flow as described in CCPS GPREH 2nd Edition §4.41 are typically employed. Any normally closed valve…

A control valve on the inlet to the container that is connected to a high pressure reservoir can fail open to introduce excess material. The calculation methodologies described in Control valve flow are typically employed…

The Tube failure characterization (CCPS GPREH2 trim) closed with the nine ISO 23251:2008 aspects that bear on the likely failure mode.1 The following evaluation criteria are recommended to help determine the effects that those aspects…

Tube failure in a shell-and-tube heat exchanger is the common structural-failure basis for overpressure protection.1 Before the relief load can be sized, the designer has to decide what kind of failure to design for. The…

The structural failure scenario is a special case of excess inflow.1 The method of estimating the flow through the break depends on the service and the specific type of equipment. After establishing the flow rate…

In the event of an imbalance in the volumetric flows in and out of a container, a change of pressure can result within the container. The flow rate entering and exiting the container can be determined using common engineering calculation techniques, either by evaluating the capacity of a single limiting source term or single piping component, multiple piping components in series, the limitations of a fluid driver, or the combined effect of the fluid driver and the intervening piping system. Several cases of overpressure scenarios are evaluated in this manner, including heat exchanger tube failure, inlet control valve failure, and inadvertent valve opening.

The transfer of heat into or out of a constant volume container results in an attempt of the entrapped fluid to change in overall density, leading to pressure increases or decreases. The change in fluid…

When performing pressure relief analysis, the blocked system outlet is one of the most common overpressure scenarios requiring consideration.  A blocked system outlet can occur on almost any piece of equipment.  A blocked outlet may…

All control valves, regardless of their fail-safe position, have the potential to go wide open.  Failure open of an inlet control valve is typically considered an applicable overpressure scenario for a pressure vessel when the…

Many of the relieving requirements for credible overpressure scenarios we calculate implicitly assume that the only mass/energy allowed to leave the system is through the relief device; however, there are some instances of reasonable attempts…