Node Numbering Conventions - PDS - Help

Plant Design System (PDS) Stress Analysis Interface (PD_Stress)

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The last set of fields generated on each overall component record is the node number set for the component. The node number set identifies the node number of each node on a component. The following conventions are used in assigning the node numbers in the set:

  • Straight through components (pipe, reducer, rigid bodies, flanges, etc.)

    Only the connect points are given nodes. These types of components will only have two nodes. Internal nodes are never generated.

  • Straight through valves with hand-wheel operators

    Nodes 1 and 2 are generated at the valve connect points. Node 3 is generated at the valve center. If the valve operator has a center-of-gravity defined, a fourth node is generated at the center-of-gravity.

  • Tee type components

    Nodes 1 and 2 are generated at the connect points on the run of the tee. Node 3 is generated at the branch connect point and node 4 is generated at the center of the tee.

  • Olet and branch weld type components

    Only two nodes are generated, one for each connect point.

  • Elbows and bent pipe

    Nodes 1 and 2 are generated at connect points. Node 3 is generated at the component origin.

  • Eccentric reducers

    Nodes 1 and 2 correspond to the two connect points. Elements 3, 4, and 5 in the node list are the components of a vector that orients the flat side of the reducer.

  • Two-way valves

    Nodes 1 and 2 are generated at the connect points. Node 3 is generated at the component center. If the valve operator has a center of gravity, node 4 is generated at the center of gravity.

  • Three-way valves

    Nodes 1 and 2 are generated at the connect points from the run of the valve. Node 3 is generated at the branch connect point and node 4 is generated at the component center. If the valve operator has a center of gravity defined, node 5 is generated at the center of gravity.

  • Pipe supports

    Pipe supports that are not converted to node restraints by the interface will have two nodes. The first node is generated at the point that the pipe support attaches to the pipe line. The second node is a dummy node and simply defines an orientation for the support.

To a certain extent, you can control the node numbers assigned to nodes. You do this using the options file options. The PD_Stress Analysis Interface distinguishes between three types of nodes in a piping network:

  • nodes at connections between components

  • nodes internal to components (nodes at the center of elbows or valves)

  • nodes at network endpoints.

You can specify the starting node number for each of the different node types. For nodes at component connections, you can also specify the increment to use in generating the next node number. Refer to the Options File section for more information.