Difference bet. Piping in Petrochemical and Pharmaceutical

What's different?
It might be easier to list what is not different.
In general there are two types of systems in a pharmaceutical plant. Basically they are the product related systems and the non-product related systems.

The piping material and the piping design methods for the non-product related systems would tend to be the same as for any other type of plant. The exception would be if the client had other restrictions or requirements.

The piping material and the piping design methods for the product related systems would all be very different.
Such as:
The pipe material will tend to be special stainless steel.
The method of connection may be welded for all sizes in some systems and quick disconnect joints (Tri-Clover, etc.) in other systems.
The valves may tend to be "Diaphram" valves in all systems that require "CIP" (Clean-in-place). These valves also require an installation position that allows the body cavity to free drain. To do this the valve stem must be oriented 17 degrees to 22.5 degrees above the horizontal center line.
Lots of the systems will be restrictive about dead legs, NONE ALLOWED.

There is more, much, much more and I'm sure others will be able to offer their thoughts and advice.