I think the OP's question is too general. There are too many personal preferences on how things "should" be connected for there to be a one-size-fits-all schematic. I imagine the members of this forum could come up with at least 50 schematics that would be different in some way.
The OP provided no details about the application: Is there steam on one side? How big is the piping? Is the question about welded-plate heat exchanger?
Better to ask a specific question, such as: is it necessary to use eccentric reducers if they are in the horizontal pipes to the inlet connections? There may be a variety of answers pro and con, but it would focus the discussion and demonstrate that the OP looked at a few on-line resources before asking an unanswerable question.