I finished reading Ken Follett's 'The Pillars of The Earth'. It is a story of 12th century stone mason who laboured his life to build a cathedral. It describes Civil Engineering practices of that phase. That is when I started thinking about Piping. There are quite a few examples which we may or may not appreciate today. I'm listing a few that I felt. I may be wrong in imagining but still I thought it is worth sharing.

A] Fittings: These fittings must have been developed after continuous requirement as below:
Elbow: To assist directional change (perhaps Mitre preceded Elbow)
Tee: Provision for branch off / distribution
Reducers : Change in size / Transition
Flange: To fit in a component like valve / spectacle which will not be welded due to operation / maintenance requirement. Of course, there are welded valves.

B] Standards: Standardization of dimensions meant we can buy the material from any vendor without having to wonder it'd fit or not. Performance standards gave us the safe working range for which the selected material is suitable. Ratings are a blessing.

C] Pipeclass / Specification: A single material category identification for a line must be a great idea. That saves us all from having to look at long material descriptions. We just have to pick up the relevant pipeclass, rest happens automatically.

D] Plant North: Not all plants are aligned with geometric north. To have ease in drawings, this must have been devised.

E] Manifold: If you were to provide multiple services to an equipment then instead of puncturing the vessel shell at as many locations, a pipe would be used like a header to which these services would connect. The manifold will connect to the vessel at once. Manifolds are useful for steam tracing as well. Small trees that branch off steam.

There will be a lot more. A lot of thinkers in the past have done great work that is why we can work with ease today.

Sir Isaac Newton had famously said: