When the coordinates and/or the orientation of the 3D model elements do not align with the World coordinate system and/or cardinal axes and the required positional coordinates displayed on Piping isometrics need to be referenced from an alternate element other than the WORLD /*.
Resolution
Using the AXES command in ISODRAFT will help resolve this issue.
By default, all spatial coordinates on isometrics are given in the World coordinate system, the WORLD /*. The AXES command allows the user to specify an alternative coordinate system for the isometric by referencing another named database element other the World. The referenced element must have a Position and Orientation, typically, SITEs, ZONEs, and DATUMs are used with the AXES command.
All coordinate positions and orientations displayed on the piping isometrics use the element identified in the AXES command. If needed, instead of using the standard setting ….. AXES WORL /* …. you can using an alternative named element such as a SITE, ZONE< DATUM … i.e. AXES /PROJECT-REF-CORD … which can have its Position and Orientation attributes set to alternative values (i.e. Position E20000 N20000 U3000 and Orientation Y is N 45 E and Z is U). Then, all coordinate positions and orientations displayed on the isometric will reference the element identified by the AXES command.
In addition, AXES command is often used for skewed models, that is, where elements are not modelled in the North direction i.e. Y is N 45 E. In this case, you would need to create a SITE, ZONE, or DATUM (i.e. SITE /PROJECT-REF-CORD) and set its Position attribute at the preferred reference location (i.e. a benchmark or Southwest corner column of the primary structure) and set the Orientation attribute, Y is N 45 E and Z is U. Then, in your Isometric Options file, use the command i.e. AXES /PROJECT-REF-CORD.
To test your results, run a piping isometric and verify the results.