• A PFD/UFD  is a schematic drawing of a process or utility unit which explains the overall scheme of the process flow for a plant
• Used for HAZID (Hazard identification) study
• PFD’s / UFD’s are prepared under the responsibility of the process or utility engineer
• No modifications to a PFD / UFD shall be made without his authorization

What is included in a PFD/UFD?

• Process/Utility Piping
• Major equipment symbols, names and identification  numbers
• Control valves and valves that affect operation of the system
• Interconnection with other systems
• Major bypass and recirculation lines
• System operational values as minimum, normal and maximum flow, temperature and pressure

What is piping and instrumentation diagram?

• Piping and Instrumentation Diagram explains the conceptual requirement of the plant and the facilities to be built.
• Shows the interconnection of process equipment and the instrumentation used to control the process.
• P&IDs are prepared under the responsibility of the process or utility engineer. No modifications to a P&ID shall be made without Process engineer authorization
• Basic process input document for development of plant layout and piping
• Provides the basis for the system control and shutdown schemes, allowing for further safety and operational investigations, such as the hazard and operability study (HAZOP)
• Used to identify systems for hydro test

Types of piping and instrumentation diagrams

• General  : Legends and Typical (Symbols, System identifications, Sampling, PSV Manifolds, Pumps drains, etc.)
• Process : Process systems
• Utility : Utility generation systems
• Distribution : Nitrogen, Air, Water, Steam, Condensate, Flare, Sewer, Drain system, etc.
• LOSPE : Fire water, Foam system etc.

What is Legend Piping and instrumentation diagram P&ID?

Legend P&ID used to read and understand the below points,

• Line type and designation
• Valve types
• Insulation types
• Type of flow meters
• Specialty items
• Typical assemblies

Important points to read in Process and utility P&ID

• Read all Notes on PID
• Equipment elevation requirement.
• Min from Grade
• W.r.t to other equipment
• Line requirement
• Slope
• Free drain
• No pockets
• Min or Max requirement
• Scope of supply break
• Piping class break and flange option code.
• Battery limit requirement.
• Design parameters indication
• Thermowell installation on small bore
• Flare line connection to header
• Dyke/Curb wall requirement
• Equipment located inside Pit

What is the difference between P&ID and PFD?

PFD	PID
This diagram depicts overall scheme of process flow	This diagram shows the piping and instrumentation details of process.
This diagram shows the equipment and flow details with process parameters like Flow, temperature, pressure, heat and material balances.	This diagram shows the Piping, instruments, equipment connections with basic process parameter like temperature and pressure.
Used for HAZID study	Used of HAZOP study
Single sheet is sufficient to cover a system	More sheets are required to cover one system to provide more details.

What is Distribution Piping and instrumentation diagram (P&ID)?

• Distribution network for utility services like Nitrogen, flare, Air, steam, condensate, water
• Prepared based on the layout arrangement of Utility Piping header and its branch offs from/to Process P&IDs

What is LOSPE piping and instrumentation diagram?

• PID developed by Loss prevention department for Firewater and Foam Services to protect critical equipment’s in a plant
• Firewater Ring Network details
• Deluge Network for Firewater and Foam services of Individual Equipment