Piping > Routing > Associativity Between the Routed Pipeline and the Reference Pipeline
  
Associativity Between the Routed Pipeline and the Reference Pipeline
The offset that you specify for the Set Start of a new pipe segment that is to be routed, is calculated from a reference pipe segment that has the biggest outer diameter in that pipe run.
 
* Spec-Driven Piping does not consider the insulation diameter for offset calculations.
When you change the biggest outer diameter of the reference pipe segment by either using the Modify Pipe dialog box or by inserting a reducer on the reference pipe segment, the actual distance is changed between the reference pipe segment and the new pipe segment created after routing. This maintains the offset that you specified earlier.
In the following figure, the pipe segment in black is the reference pipe segment and the pipe segment in green is the new pipe segment created after routing. Before a reducer is inserted on the reference pipe segment, the distance between the reference pipe segment and the new pipe segment created after routing is as shown:
1. Original centerline distance
2. Original offset distance
After a reducer is inserted on the reference pipe segment, the distance between the reference pipe segment and the new pipe segment created after routing is updated as shown in the following figure:
1. Changed centerline distance
2. Original offset distance maintained