Physical Size and Mechanical Design Information
The physical size and mechanical design information almost universally found on P&IDs for all major processing and production facilities is as follows:
• Piping elements. Nominal pipe diameters and sizes of valves, flanges, reducers, connections and miscellaneous and special fittings
• Columns, vessels, tanks. Internal diameter(s) (“ID”), seam-to-seam height(s) or length(s) and equivalent boot and dome dimensions
• Relief valve setpoints
Additional Mechanical and Process Information
Major processing plants usually control operating conditions by varying feed stream composition, throughput, heat input, etc. As a result, relief valve setpoints are usually the only mechanical design information shown on the P&IDs. By contrast, additional mechanical design and (sometimes) process information (such as design temperatures and pressures, duties, horsepowers, speeds, capacities, and throughput) are shown on production facility P&IDs, because actual conditions can be quite different than anticipated.
Some operators of major processing facilities now request expanded equipment information on their P&IDs. This information can be of considerable help in operations, and in estimating and designing additions and modifications.