Equipment Nozzle Placement Rule Example

The Nozzle Placement Language is as illustrated using the "Vertical Vessel Nozzle Placement Rules", below.

The equipment nozzle placement rule starts with an Equipment Identification header, followed by Nozzle Placement Rules. There may be many rules for nozzle placement within an equipment type that apply for different conditions.

Each rule is preceded by an optional condition clause that is used to specify the group of nozzles for which this specific placement rule applies. In the VERTICAL_VESSEL example, the nozzle types are: manways, inlets and outlets. The actual placement rule starts with the key phrase LOCATE nozzle with. Each LOCATE clause starts by defining the element of the equipment on which the nozzle is placed. In the VERTICAL_VESSEL example, all the nozzles are placed on the VESSEL element. Each element may have a number of faces, depending on its elemental geometry shape. In the VERTICAL_VESSEL example, the vessel element is a cylinder which has the faces body, top and bottom. All nozzles in the VERTICAL_VESSEL example are placed on the body face. Once the face is selected, the nozzle is placed. The placement may be absolute or relative to other already placed nozzles, other equipment or structures on the plot or the direction in which the other end of the connected pipeline is located. For a complete description of all the options, look at the complete language specification in Appendix C - Language Syntaxes.

In the VERTICAL_VESSEL example:

the first manway is placed a distance of 30 inches or 750 millimeters (depending on unit system) along the surface of the vessel body from the bottom (which is the origin of the face) in the direction of the axis of the cylinder (up) at an angle which places the manway away from the nearest pipeway;
the inlet nozzles are placed 18 inches below the top of the vessel; and
the outlet nozzles are placed one-third up from the bottom on the side of the vessel facing the nearest pipeway.

The OFFSET keyword defines relative distance from already-placed nozzles. In the VERTICAL_VESSEL example, the following manways are spaced (OFFSET) evenly up the vessel from the first manway. This relative distance is calculated using the vessel length and the number of manways.

The inlet and outlet nozzles are all spaced by an angle of 20° (offset-angle) from the previous nozzle in the direction of the other end of the connected pipe (toward-otherend).

Note: if there are no clauses that separate inlet nozzles from outlets, the inlets will place before the outlets.

Nozzle placement can be controlled with a number of keywords as seen from the VERTICAL_VESSELL example.

Placement dimensions can be determined with logical expressions written in infix notation. The infix notation is described in more detail in Appendix C - Language Syntaxes. These expressions may use attribute values from the equipment, from the elements of the equipment and from the nozzles, both the current nozzle and previously defined nozzles. The binding to various variables is discussed in Appendix C - Language Syntaxes. The calculations must result in values in the selected unit system.

To address a nozzle property, use the prefix nozzle. In the VERTICAL_VESSEL example, the first rule checks whether or not a nozzle is a manway

(nozzle.nozzle_type_input is manway).