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What is an astute P&ID??

Updated: Oct 22

Before getting deep into creation of P&ID document we must know its background!

  • What is P&ID

  • P&ID symbols

  • How to create one

  • P&ID interpretation

  • Summary


What is P&ID- For the maximum approach to control process equipment and instrumentation, a document is created which is detailed to provide the basic idea of engineering. The document has user requirement specifications but in the form of drawings. A kind of “road map” telling us what the instruments are playing where they are located, and how they will interact with the rest of the plant. The piping and instrumentation diagram (P&ID) shows pipelines, equipment, instrumentation, and control systems found in biotechnology, chemicals, Probiotics, and various industries. Manufacturing facilities have compressed air, steam, chilled water, and other processes that require the use of piping, all these processes require instrumentation to control them which is usually in the form of gauges, pumps, and accumulators. All the things are detailed on paper for a better understanding of the process flow.



P&ID symbols- The international society of automation (ISA) has defined a standard for P&ID. The standard is ANSI/ISA-5.1-2009 and is available on the ISA website. To document all the things on one paper, there is a need for an engineer, who can illustrate the functional concept using a standard layout and set of symbols. This format contains tag numbers present on the valves which enable the user to understand the process flow and highlight major steps for emergency cases. These symbols are also labeled with words, letters, and numbers to further identify and specify the components that they are representing. The symbols can vary by industry, projects, and client requirements, anybody such as control engineers, technicians, and maintenance personnel working on control systems of equipment heavily depend on P&ID and its symbols. Original symbols and terminology for P&ID were created long before the introduction of PLC, before computers each process had its controller. Control rooms were massive and had several control panels with lots of controllers and other devices such as strip chart recorders and switches. But nowadays, computerized systems using virtual controllers found in PLC are easy to use and for these developed symbols are created by expertise. Defined symbols can be used repeatedly within the projects this prevents errors caused by copying existing projects and ensures good knowledge management.

Software applications designed for this purpose are often the first choice in mechanical and plant engineering. What we use at Amerging Technologies is AutoCAD by our appropriate trained and expert Mechanical engineers with the necessary experience in CAD drawing and for 2D and 3D drawings of the fermenter, we use Solid works software.


(for reference visit P&ID valve symbol library by Jeff Ringer., 21.12.2017)


How to create P&ID- Drawing a P&ID includes the basic equipment layout and basic process control systems. It can be drawn by dragging process engineering equipment shapes onto the drawing page, connecting them with "smart" pipelines, and then dragging components, such as valves and instruments, onto the pipelines. Add data to components in the diagrams and generate lists of equipment, pipelines, valves, and instruments. Optimizing the P&ID design process not only simplifies the task of drawing the P&ID but also transforms a P&ID into an efficient source of information for the subsequent engineering phases. Following steps can be taken while creating a map:

  1. The efficient design of the plant system- The design of a plant is determined by the desired bioprocess. Before creating P&ID, one must know the scope of the overall process. Requirements for a plant should be in mind and what does it achieve as a product.

  2. Inputs and outputs- Manual and automatic components are described in this part, connections from starting point to the endpoint through which feed and product streams can be identified. Pneumatic valves, ball valves, sampling valves, pneumatic diaphragm valve, safety relief valves, feed, water supply, inlet exit gas, circulation from the reservoir, waste condensate, steam condensate, and effluent removal are all the parts that are the user’s responsibility to provide.

  3. List of equipment and components- Correct equipment according to the control over the supply, discharge, homogeneous mixing of mass, cooling capacity, heat distribution, oxygen transfer, and dissolved oxygen should be considered including added costs to the process. Other processes like sterilization of vessels, CIP process, and their entry-exit points including the components required in this process should be in mind while designing the layout of the flow.

  4. Process flow- Process flow is a term used to describe the general flow of plant processes and the equipment used in chemical and process engineering, often depicted through a diagram. A process flow diagram should show the relationship between major equipment used in a plant facility.

  5. Measurements and numbering- All the above-mentioned equipment and components are once drawn on the sheet, numbering is provided to each component for easily distinguishable requirements.


Reading P&ID- The first letter of the code identifies the parameters that are being controlled or monitor e.g., Flow, temperature, level, pressure, etc. the next letter is used to define the type of control device being used e.g., Transmitter, valve, or controller. The number refers to the logical numerator.

The best way to learn is by example. We have shown a small part of the P&ID from one of our projects and if we see clearly, there is one vessel through which chilled water (CW) is passed and eventually this water will be discarded through drain. This chilled water is going to regulate the low temperature around the vessel covered with SS jacket.

Suppose we take PAV25B10 symbol it denotes that Pneumatic angular valve of size 25 designated as no.10 is placed providing linear actuation to lift a seal off its seat.

Similarly, Non- return valve ( denoted as NRV) allows steam to flow in one direction and automatically prevent back flow.

HE- Heat exchanger, CP- Circulation pump, ST- Steam trap.


Procedure for this P&ID is that chilled water is passed from CW line to opened valves PAV25B10, PAV25B14, CP01, HE01, NRV2501 into the jacket and meanwhile the valves PAV25B11 should be closed to achieve desired temperature maintained for some time. After maintenance when there is need to drain water valves PAV25B11 should be open and for this moment valves PAV25B10, PAV25B14, CP01, HE01, NRV2501 should close.

Summary- In this blog, we have learned that for document preparation and creating a P&ID there are things needed to keep in mind before starting from design/connections to the rest of the process. The first step is to determine the scope of the process which is generally user specific, by determining the input and output components, a list of equipment, an overview of process flow can be made. Still, optimization is always required after rough work, and it can lead to a more sorted outcome. Reading P&ID is also very time-consuming; this is the point where the user should work hard to make it look cleaner and more understandable. This can be done by using common standard identification codes and symbols which are used abundantly in industries.


We’d appreciate your suggestions on this topic for more add ons.


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