PIPING ISOMETRICS: SYMBOLOGY DEFINITION - MORE

Each new symbol must be generated as a special block using the menu command: PD_ISO / Block Definition, from a 3D model or isometric drawing file. It prompts to select the component code and its iso equivalent end codes, defined in the ISO_SYM field of the system table /STD/END.DBF (only the first end code is to be specified if the second one is equal to the first):

Following that, the Center must be selected, as well as each Connection Points and select the elements comprising the symbol.

The following references must be taken into account:

• Dimensions. Isometric symbols that came with the system are defined using a 5 or 10 units module.
• The Connection points for flanged ends are defined on the flange faces and, during the isometric generation, are automatically moved by 0.5 units. In this way, two connected flanged components are separated each other by 1 unit, representing the gasket thickness.
• Pipes don't need an isometric symbol, because are automatically drawn using a LINE, with attached properties.
• TAG. If the 3D component contains attributes to be used for TAG, the same attributes must be added in the corresponding isometric symbol: in this way, during the isometric extraction the attribute value will be copied to the isometric symbol.

To maintain symbol consistency, it is convenient to respect these rules or modify all components with similar ones.

Isometric symbols are inserted in the drawing file with scale equal to 1, unless specified another value in the Drawing Criteria option.

If an isometric symbol is not defined with the EPLANT command, for example is a simple AutoCAD block, during the extraction will be discarded with an error message.

To define an isometric symbol the following sequence can be used as a guide:

• Identify the UCS associated to the corresponding 3D component.
• Identify the block insertion point, generally is the 0,0,0 of the block UCS.
• Identify each one of the component connection points, using the command PD_UTI / Generic / Connection Points with the only objective to see their orientation with respect local block UCS.
• Draw, or better, insert a similar symbol and explode it. For standardization purposes use as end symbols the BW, SW, SC, RF blocks that are contained in the existing symbols, depending on their ends. Define an UCS oriented with respect the symbol in the same way the 3D component UCS.
• Take the PD_ISO / Block Definition command, from an isometric drawing or from a 3D model, being this last case the most common one. Place the symbol connection points with the same orientation as in the 3D component, with respect both UCS.
• This command allows to save the newly created symbol in the project isometric symbol directory.

In the case of Cut Elbows the isometric symbol is automatically generated using the corresponding "half elbow" symbol. These symbols have the following names: iso_e_bw, iso_e_sw, etc. depending on the end code.

IMPORTANT: to generate isometric symbols, always use a void drawing file or, at least without any AutoCAD solids elements, to avoid generating symbols with incorrect structure that will not be accepted during their use in an isometric extraction.

Few components (those with the ISO_PDL field = 1 in the COD.DBF table) require a dynamic definition of the isometric symbol. Refer to the Technical Manual chapter 7 for details.

Last updated April 16, 2015.