The Natech risk analysis methodology of RAPID-N is based on the estimation of Natech scenarios for plant units located at industrial plants. Hence, the focus is on plant units and their characteristics, including their structural and functional behaviour against natural hazard impacts and the hazardous substances present therein.
Although there are different types of plant units in an industrial plant, Natech risk analysis methodologies developed so far mainly focused on storage tanks. Since Natech events are directly related with hazardous substances, and storage tanks generally contain such substances in large quantities, it is reasonable to give priority to storage tanks. However, other types of plant units are also important and may cause major Natech accidents. For this purpose, RAPID-N supports not only storage tanks, but also other types of plant units. An example plant unit data entry form is given in Figure 24. For each plant unit, the type of unit (e.g. storage tank, reactor), the industrial plant that the unit belongs to, a unique plant unit code, descriptive and geographic location, and the substance contained within the unit can be indicated. Additional data, such as dimensions, structural characteristics, and safety measures, can be entered as property values in the properties list.
The system allows a plant unit to be present without being linked to a specific plant. This is mainly to support plant unit data originating from 3rd party sources, such as open collaborative mapping projects, which can provide geographic data on plant units (e.g. storage tanks) without explicit reference to associated plants. Therefore, only the unit type is mandatory as input. However, entry of other data including some properties is necessary for carrying out a risk analysis.
Remark. Associated plants
RAPID-N automatically transfers site-specific properties (e.g. on-site hazard parameters, meteorological conditions), from the related plant record to the plant unit record, if plant-unit specific values are not specified. Therefore, indicating the plant of the unit is useful for the analysis.
You can indicate the location of the plant unit and delineate its boundaries on the map as described in detail in the Mapping section. The delineation process is identical, but enhanced for plant units with circular cross section (e.g. cylindrical storage tanks). Because the boundaries of such plant units are better described by circles instead of polygons, the system automatically switches to circle editing mode based on the "Shape" property. Because the feature editing mode depends on the "Shape" property, but not the type of the plant unit, circular editing is not limited to storage tanks. You can also delineate other circular units, such as columns or stacks.
Hint. Plant unit location
The location of the unit is used to map the extent of the estimated consequences as part of the Natech risk analysis. Hence, it is necessary to provide the location data to obtain proper Natech risk maps at the end of the analysis.
The substance stored in the plant unit can be specified by selecting a substance from the list of substances available in the system. If the substance stored in the plant unit is not specified, the system cannot determine the potential consequences during the Natech risk analysis. Therefore, in the absence of the substance information, consequence analysis cannot be performed and only the results of the damage analysis can be reported.
Hint. Substance data
For a complete risk analysis, the substance stored in the plant unit must be specified. If the substance cannot be identified with certainty, a substance that has similar hazardous characteristics to the actual substance can be specified as a substitute. For example, Kerosene can be used as a substitute for fuels which are not very volatile.
Figure 24. Example plant unit data entry form
The availability of data on other plant characteristics is also important and directly affects the analysis process. Although the system tries to estimate the missing data, the more data is provided to the estimation framework as input, the better and accurate the estimates will be. Therefore, it is good practice to provide all available data for each plant unit to the system.
Remark. Plant unit type
The list of plant unit properties that can be entered for each unit depends on the type of the unit. Therefore, before entering the properties make sure that you choose the proper plant unit type.
The extent and severity of the Natech-related consequences mainly depend on the hazard characteristics and amount of the hazardous substance stored in the plant unit. Therefore, plant unit properties that allow the calculation of this information are important for the analysis. Besides the substance, at minimum the following properties should be provided for a proper analysis:
— Volume (either directly or by providing unit dimensions, e.g. diameter and height) — Filling level (either directly or by providing filling percentage or filled volume)
— Storage condition (either as category, e.g. atmospheric or pressurised, or by providing storage pressure and temperature)
Providing the following properties is also highly recommended to increase the accuracy of the analysis:
— Shape
— Dimensions (e.g. height, length, diameter) — Base type (e.g. on-ground, above ground) — Base support (e.g. anchorage)
— Mitigation measures (e.g. secondary containment or dike, if possible with dimensions) Although the data in the form given in Figure 24 is not complete, it illustrates the minimum information which should be provided. As indicated before, the system is capable of estimating additional property data by using the available data. Figure 25, which is the information page corresponding to the plant unit data entered in Figure 24, illustrates this capability. In the figure, the properties indicated in red are estimated by the system. The system includes data on more than 64,000 plant units, mainly storage tanks, world-wide, which is collected from public sources, such as OpenStreetMap. However, due to confidentiality reasons this data is not publicly accessible. In order to access the data, please contact the administrators by using the Contact Form of RAPID-N.