You can modify the length of plumbing line segments using lengthen grips 
. Because the grips constrain a segment to its current angle, they are particularly useful for modifying the length of plumbing line segments you have already placed.
When you use the lengthen grip on an end that is connected to another object, you must specify whether you want AutoCAD MEP 2022 toolset to maintain connectivity between the objects.
Lengthen grips on plumbing line segments
The following example illustrates how a plumbing line segment in a vent system is lengthened. To avoid interference with a duct system, the software adjusts connected objects to maintain their connectivity.
Plumbing line segment selected
Lengthen grip selected
New length specified
Resulting layout