Cannot Connect Parts errors encountered problems

[khmin]

i have a few questions

1. When I create a custom Parts, Metric units using, Cannot,Connect Parts errors encountered problems. (Figure 1)

1. Want to know how to connect with the force, when I see water drop mark form 3D model

(Figure 2)

[dave.wolfe]

Flanges are required to have the pressure class and facing properties filled out and matching to connect mating flanges.