Plant Unit Types

Although there are different types of plant units in a plant, natech risk assessment methodologies developed so far mainly focused on a single type, which is the storage tank. Since natech events are di-rectly related with hazardous substances and storage tanks generally contain such substances in high quantities, it is reasonable to give priority to storage tanks in risk assessment. Moreover, numerous studies highlighted the vulnerability of atmospheric storage tanks to natural hazards (Krausmann et al, 2011; Salzano et al., 2003; Shih, 1981). However, other types of plant units are also important and may cause major natechs. Considering this fact, RAPID-N supports not only storage tanks, but also other types of plant units by providing a generic plant unit type definition mechanism for the administrators.

The data fields of the plant unit type records are listed in Table 1.

Table 1. Plant unit type data fields

For each plant unit type, a descriptive name should be entered and plant unit properties valid for the unit type should be indicated (Figure 1). Since plant unit properties are defined independent of the plant unit type, not all plant unit properties are valid for every plant unit type. For exam-ple, the storage condition property is meaningful only for storage tanks. Hence, it should not be listed on plant unit data entry forms for other types of plant units. This cross-check is automatically per-formed by RAPID-N by using plant unit properties defined for each plant unit type. Valid plant unit properties can be selected from the list of plant unit properties provided by the system, which includes all plant unit properties found in the database. Selection of at least one property is mandatory.

REMARK: Plant unit types can be accessed only by the administrators.