The piping & instrumentation diagram (P&ID) is a highly important document for process plant design. Despite its simplicity, it contains a wide-range of detailed design information. But what exactly is behind a P&ID?

What is a Piping & Instrumentation Diagram?

A P&ID is the basis for pipework design

Piping & instrumentation diagrams (P&IDs) are used to schematically represent a design, and are usually created before any physical equipment design or layout takes place. All of the equipment and instrumentation required for a process is depicted using symbols, and any interconnecting pipework is represented using simple lines. P&IDs contain a considerable amount of detailed information about the design such as equipment tags, line labels, bore sizes, quantities and connectivity. But how can so much information be accommodated within such a simple diagram?

The aim is to achieve meaningful simplification

The use of symbols is fundamental to creating a P&ID. Symbols must be simple and easy to remember, while at the same time clearly depicting the function of the equipment they represent. Frequently used symbols for equipment such as pumps, blowers and tanks will typically appear multiple times on a P&ID. Each symbol is labelled with a unique tag number to ensure it can be unambiguously identified.

Making processes visible

Another design task is to show how equipment is connected. This is achieved using simple process lines to represent the interconnecting pipework. When complete, the P&ID acts as an important reference document for all downstream design tasks such as equipment layout and the routing of pipework. It is also used to prepare parts lists to assist with choosing suitable components and for project costing purposes.

Create a P&ID, but with which software?

Modern P&ID software packages offer a range of standard symbol libraries to enable P&IDs to be quickly drawn up. The pipework between individual components is represented using simple process lines. Additional tools enable equipment, instrumentation and process lines to be uniquely labelled to ensure they are unambiguously defined. Although this functionality is included with most P&ID software packages, it does not guard against design errors.

“A piping & instrumentation diagram is a highly important document used for process plant design and contains a wide-range of detailed design information.”

Creating P&IDs – Without Errors

One of the biggest advantages of modern P&ID software packages is their ability to automatically check the entire design for consistency and errors during the drafting process. The latest P&ID systems generate a detailed list of problem areas and highlight them on the P&ID. This allows the designer to quickly and easily make corrections and prevent the issues from affecting subsequent project phases.

The P&ID: the basis for quotations

P&IDs are commonly used for preparing quotations, but far too often the calculations are still performed manually, and are therefore prone to human error. The latest P&ID systems automate this task by deriving parts lists directly from the P&ID. The resulting lists are not only highly detailed and accurate, but can also be output in a range of useful formats for integration and use with other systems.

High level of design detail

Traditionally, P&IDs contained only a limited amount of information about a design, but current P&ID software packages offer the capability to enrich P&IDs with user-defined attributes to produce highly intelligent P&IDs. Attributes can be assigned to equipment and instrument symbols, as well as process lines. Attribute values can either be freely specified by the user or constrained to set values. Typical applications include the specification of pressure ratings, sizes, materials, pipe contents, capacities and temperatures, the possibilities are almost endless. Attributes can be visible on the P&ID, or hidden from view, but they are always available for output to automatically generated listings. This eliminates the need for additional documents and improves data re-use and integration with other company systems.

A modern P&ID system

One software package that stands out due to its intelligence and sheer flexibility is CAD Schroer’s M4 P&ID FX. This system is highly affordable and has all the functionality you need to quickly and accurately create intelligent P&IDs. Its extensive attribute capabilities and customisable parts list generation set it apart from other packages on the market, which often cost a lot more but do a lot less. It is also extremely easy to use, and is supported with video tutorials to help you get started. P&IDs are the basis for process design. They can be quickly and accurately created using modern P&ID software to ensure a high quality design.

P&IDs are the basis for pipework design. They can be quickly and accurately created using the modern P&ID software to ensure a high quality design.