FAQ

What is a P&ID drawing?

A P&ID drawing (piping and instrumentation diagram) is a schematic diagram that represents the instrumentation and piping system used in industrial processes. P&IDs use standardized symbols and notation to represent the various components of the system, including pipes, valves, pumps, and instrumentation.

P&ID drawings typically include several types of information, including:

• Process flow: the direction of flow and the sequence of operations.

• Process instrumentation: the type of instrument, its function, and its location.

• Process control: the control valves, signals, and interlocks.

What is the purpose of P&ID?

A piping and instrumentation diagram (P&ID or PID) visually represents the piping and instrumentation process system used in industrial processes. P&IDs use symbols and notation to represent the system’s various process equipment and components, including pipes, valves, pumps, and instrumentation.

The primary purpose of P&IDs is to provide engineers and designers with a detailed understanding of the piping and instrumentation systems used in industrial processes. By clearly and concisely representing these systems, P&IDs allow engineers and designers to design and construct safe, reliable, and efficient industrial plants. A P&ID also enables construction personnel and maintenance technicians to understand the plant’s systems and operate and maintain them effectively.

Furthermore, a P&ID is used to identify potential hazards in the plant, such as high-pressure areas or hazardous chemicals, and to ensure that the plant meets regulatory requirements for safety and environmental compliance. A P&ID can be used to identify potential areas for improvement in the plant’s systems, such as reducing energy consumption or improving process efficiency.

What should a P&ID include?

The components that are typically included in a piping and instrumentation diagram are:

• Flow directions

• Process piping, including their sizes and identifications

• Mechanical equipment labelled with names and numbers

• Permanent start-up and flush lines

• Valves and their individual identifications

• Interconnection references

• Identification of process components and subsystems.

• Instrumentation and their associated designations

• Control inputs and outputs, as well as interlocks

• Interfaces for class changes

• Computer control system identification and input

• Fittings, such as vents, drains, reducers, increasers, and swaggers

• The desired physical order of the equipment

• The equipment’s capacity or rating

What are piping and instrumentation diagram (P&ID) symbols?

Piping and Instrumentation Diagram (P&ID) symbols are standardized symbols used in the design and construction of industrial plants to represent the various components of the piping and instrumentation systems. The symbols provide a clear and concise representation of the system, allowing engineers and designers to design and construct safe, reliable, and efficient industrial plants.

Some of the commonly used P&ID symbols include:

1. Pipes and fittings, such as straight pipes, elbows, tees, valves, and reducers.

2. Instruments, such as sensors, transmitters, gauges, indicators, recordings, and controllers.

3. Pumps, compressors and fans, such as centrifugal pumps, positive displacement pumps, fan blades, and reciprocating compressors.

4. Heat exchangers, such as shell and tube, plate, boilers, condensers, and air conditioning heat exchangers.

5. Tanks and vessels that store fluid, such as storage tanks, reactors, and separators.

6. Equipment, such as compressors, conveyors, motors, turbines, and vacuums.

7. Valves, such as rotameters and orifices.

What is the difference between P&ID and PFD?

A P&ID and a PFD are two types of engineering diagrams used in the design and construction of industrial plants. While both types of diagrams are used to represent the systems used in industrial processes, they differ in their level of detail and the types of information they convey.

Piping and Instrumentation Diagram (P&ID or PID)

P&IDs are used to provide a detailed representation of the piping and instrumentation systems used in industrial processes. They use standardized symbols and notation to represent the various components of the system, including pipes, valves, pumps, and instrumentation. A P&ID provides a detailed understanding of the interconnectivity of the systems, allowing engineers and designers to design and construct safe, reliable, and efficient industrial plants.

Process Flow Diagram (PFD)

PFDs, on the other hand, provide a simplified representation of the process flow in an industrial plant. They are used to illustrate the major equipment and systems used in the process, including tanks, pumps, and heat exchangers. PFDs provide an overall view, but they do not provide the level of detail in P&IDs.

What are the different types of P&IDs?

There are several types of P&IDs used in industrial plants and facilities. The type of piping and instrumentation diagram used depends on the specific needs of the plant and the information that needs to be conveyed. The following list includes some of the different types:

1. Process Flow Diagram (PFD): A simplified version of a P&ID that illustrates the major equipment and flow paths of a process.

2. Mechanical Flow Diagram (MFD): A type of P&ID that focuses on the mechanical aspects of the piping and equipment, such as pump and compressor details and mechanical equipment sizing.

3. Utility Flow Diagram (UFD): A P&ID that shows the utility systems used in a plant, such as steam, air, and water.

4. Electrical Single Line Diagram (ESLD): A diagram that shows the electrical distribution system used in a plant, including transformers, switchgear, and distribution panels.

5. Logic Diagram: A P&ID that shows the sequence of events and control logic used in a system, including interlocks, alarms, and other control functions.

6. Loop Diagram: A P&ID that shows the process control loops and their components, including sensors, transmitters, controllers, and final control elements.

What are some of the limitations of a P&ID?

While a piping and instrumentation diagram (P&ID) is a critical tool in industrial plants’ design, construction, and maintenance, they have some limitations.

Lack of detail

P&IDs provide a general overview of the piping and instrumentation systems used in industrial processes, but they do not provide a detailed understanding of the equipment and systems. They may not include all the necessary information about specific components, which may be required for proper maintenance, repair, or replacement.

Potential for errors

P&IDs are typically created manually, which can lead to errors in the drafting and interpretation of the diagrams. These errors can lead to misinterpretation of the system and incorrect actions being taken during operation, maintenance, or repair.

No universal standard

P&IDs may appear differently depending on the internal standards, software system, and creator’s preferences. As there is no universally accepted standard for P&IDs, they may look different from one company to another or even within the same company.

Limited visual representation

P&IDs rely on symbols and notation to represent the various components of the system, which can be difficult for non-experts to interpret. They may not provide a complete visual representation of the system, making understanding the overall system layout challenging.

Difficulty in keeping them up-to-date

P&IDs are living documents that require regular updates and revisions as the plant equipment and systems change. As such, maintaining the accuracy and currency of P&IDs is often time-consuming and, therefore, neglected.

What are P&ID support documents?

In the engineering and design process for industrial plants, P&IDs are often accompanied by several other support documents that provide additional information and details about the systems, as well as other important aspects of the plant. The following are just some of the different support documents:

Process Flow Diagrams (PFDs)

A PFD is less detailed compared to a piping and instrumentation diagram as it provides a simplified version of the major equipment and flow paths in a process. Although PFDs provide an overall view, they lack the level of detail present in P&IDs.

Piping Material Specifications (PMS)

PMS provides detailed information on the materials and fittings used in the piping systems shown on P&IDs. They typically include information on the type of material, such as steel, copper, or plastic, the pipe size and wall thickness, the pressure rating, and the temperature rating, as well as details on the types of fittings, such as elbows, tees, and valves, used in the system.

Equipment and Instrumentation Specifications (EIS)

EIS outlines the equipment and instrumentation used in the industrial process. EIS typically includes information on the type of equipment, such as pumps, compressors, and heat exchangers, the capacity and performance specifications, and the required instrumentation, such as sensors, transmitters, and controllers. EIS also includes details on the control system used to monitor and control the equipment and instrumentation.

Functional Requirements Specification (FRS)

FRS is a document that outlines the functional requirements of the industrial plant. It provides a clear description of the intended functionality of the plant, including the process flow, control systems, and safety requirements. It also specifies the performance criteria for the different systems in the plant and serves as a guideline for the design, construction, and testing of the systems.