Basic Concepts

The PSI parsing mechanism steps through a series of branches in the sequence of the stress pipe.

Note:
A stress pipe is a collection of branches which do not need to belong to the same real pipe.

The AVEVA E3D Design pipe structure is as follows:

A pipe is a collection of two ended segments called branches. In the example below there are two branches, the horizontal segment including the tee, bend and two flanges. The second branch is from the tee to the flange. A pipe may contain multiple branches.

Branches have a start and end point known as the head and tail. These define position, direction and many other attributes that define the branch.

The simplest form of a branch is one which runs directly from head to tail with no components other than the tube between them. Most branches do have components and these are contained in a list which exists below the branch, as shown below:

A branch can be summarized as a two ended container for components.The only important rule is that the components must be in sequence, in line and face in the correct direction. Individual branch components are defined in a piping catalogue and selected from a pipe specification. The list of components may be any of the following:

Some of the listed types are obvious but others are less so, this not important for the xml description.

Components within a branch must have at least two connection points, called PPoints which define the component length and position. A tee and other multi-way components with other connection points which are connected to other branches.

The following is the pipe represented as a stress group showing the node numbers which appear in CAESAR.

What Goes in the .xml file

The body of the xml file is essentially a list. Every PPoint is listed, but only those with Node numbers are transferred to the CII file. The output contains other values but this list contains the essential attributes required to understand the concept.