The P&IDs are a graphical representation of the material flow through
a plant.  They depict process equipment such as distillation towers,
storage tanks, pumps, piping and instruments such as automated control
valves, process measurement transmitters and the associated
information 'wires'.  The different items are represented by a graphic
symbol that roughly approximates the physical outline of the
represented equipment.  The equipment items are using shown so the
primary material flows are from left to right.  So we see a sequence
of process equipment interconnected with pipe and interposed
instruments to manage the materials.  There has been a trend to
produce 'smart' P&IDs were additional information is associated
through metadata containers.  This data may either contain or link to
information to the properties of the stream or equipment and other
attributes.

The P&IDs provide a graphical representation of what is to be built,
operated, maintained and eventually retired.  On large projects, there
may be several hundred P&IDs.  They were originally delivered on paper
and linen.  Now, they are often developed in CAD and distributed as
PDFs or paper.  Although the latter have not been conducive to
supporting meta data display.

Where the P&IDs fit into the project activities and later operations:
The industrial complex lifecycle typically starts with the business
opportunity case where the opportunities are elaborated to the extent
of determining a location for the facilities to be located for the
given market.

Next, the variety of solutions are (sometimes) elaborated and
aggregated to determine the highest value grouping of technologies
(total cost of ownership compared to produced benefits).  This second
phase is typically managed by depicting the different portions of the
complex as process flow diagrams (PFDs) - how different materials are
processed through the multiple choices of technologies.  These flow
diagrams are sometimes called mechanical flow sheets and include
process information either directly on the diagram or on a separate
sheet depending upon the security and change management character of
the stakeholders.  These flow diagrams form the basis to estimating
the acquisition costs of the new assets and the subsequent 'expected'
maintenance costs.  The operating costs are addressed separately as
they deal with the meta data of materials and utilities.  These costs
are then combined to present either a single total cost of ownership
(TCO) or a cash flow diagram to help assess the alternative designs.
Once the grouping of technologies are determined, the associated
collection of PFDs are issued for subsequent use.

The third stage refines the design sufficiently to obtain a more
precise estimate of the facilities.  At this stage, the PFDs are
turned into P&IDs.  This is typically a total redraw of all the PFDs
(overviews) into detailed P&IDs were individual drawings are produced
were related equipment items are shown on one drawing constrained by
the limited size of the drawing page.  There is an opportunity here
for model based design where individual drawings would not be
committed too early but only grouped late in the project to present
'snapshots' on single drawings.

This third stage also includes determining the layout of equipment
which supports the determination of lengths of pipe and wire, and also
provides for the extent of civil work to support and cover the
equipment and area respectively.

The next stage is detailed design where the three dimensional aspects
of the project are elaborated using in a 3D model.  Now that items are
pretty well located, details of the piping can be designed and
aggregation of wire runs can be determined and wiring diagrams may
then be produced to provide artifacts for construction of the
electrical portion of the project.

The immediate view I have and would like to see how to address in
SysML is:

PFD -> P&ID -> wiring diagrams

I am very interested in obtaining view points from all.