Piping > Setting Up Fittings > Fitting Library Files > Fitting Library Creation > Mating Plane
  
Mating Plane
A mating plane is used to mate a fitting with other fittings. You can use a datum plane or a solid surface as a mating plane if it satisfies the following conditions:
The datum plane or the solid surface aligns with the x-y plane of the related port.
The normal of the datum plane or the solid surface is in the same direction as the z-axis of the related port.
 
* You cannot use a quilt as a mating plane.