Types of Engineering drawings and documents used in Instrumentation

One of the fundamental roles of an instrumentation engineer is the creation and upkeep of instrumentation documentation. This article will expose you to the various terms and forms of instrumentation documentation used in a process plant, from project design to plant maintenance.

Process Flow Diagram

Process flow diagrams (PFDs) are schematic drawings that show the fundamental details of how processes are carried out in processing plants.

It is a term that is often used in chemical and process engineering to describe the regular process flow of process plant and equipment.

 P & ID

A piping and instrumentation diagram (P&ID) is a thorough layout or diagram of the entire process plant, including instrumentation control, utilities, a control system, piping identification, equipment, instruments, valves, pipes, fittings, and a process line.

Instrument Index

An instrument index is a document that lists all of the instrument devices in the process plant.

All physical instruments, including field instruments, physical alarms, indicators, and pseudo instruments, sometimes known as “soft tags,” must have a tag number (e.g., DCS indication, alarm, and controller) which will be listed in this Instrument Index.

I/O List

I/O is an abbreviation for Input/Output.  I/O refers to any device that sends data to or from a PLC/DCS system.  

An I/O list is a document that comprises a list of the Input and Output utilized in a control system.

The I/O modules are linked to field devices such as sensors, transducers, actuators, control valves, and so on. These I/O modules are internally connected with the PLC/DCS system.

Instrument Datasheet/Specification

An instrument data sheet is a document that gives the technical details of an instrument or device. 

A datasheet will provide you a comprehensive understanding of the qualities and technical specifications of the equipment. The data sheet contains considerably more detailed information that is tailored to the application.

Instrument Loop Diagrams

An instrument loop diagram (ILD) is constructed for each process control loop. In an Automation system, ILDs give all of the necessary information concerning control loops. The ILDs are also referred as Instrument Wiring diagrams.

The ILD depicts the connection between the field and the control system, as well as the many components participating in the control loop. 

Instrument Hook-up Diagrams

An instrument hook up diagram, also known as an installation drawing, describes the scope of work between the mechanical and instrumentation departments. 

The hook up drawing explains how to properly install the instruments, from the tapping point in the process line up to the measuring and control instrument, to ensure that the instrument performs well and to eliminate difficulties that could affect the measurement.

Instrument Location Layout

The arrangement of an instrument in process area is known as an instrument location layout. This diagram displays each instrument’s precise location with respect to the plant layout.

Instrument Tray Layout

The Instrument Tray Layout is the diagram that indicates the location of the junction boxes, instrument air header, local panel, and instrument tray routing with respect to the Instrument location layout.

Instrument Cable Schedule

The Cable Schedule provides a list of all the cables connecting to instruments, junction boxes, marshalling cabinets, and system cabinets. 

Details regarding the cable number, type, size, length, termination, and glands are included in this document. 

Detailed Explanation of Instrument Cable Schedule

Instrument Junction Box (JB) Schedule

A junction box schedule is a document that lists all of the instrument junction boxes. Information like the JB position, Tag Number, Size, Make, IP rating, cable specifications, gland details, termination specifications, and earthing details are all mentioned in this document.

Instrument Air Header Schedule

The Instrument Air Header Schedule is a document that contains all of the information regarding the instrument air header and manifolds positioned in the process area.

The Instrument Air Header Schedule contains the following information:

  • Instrument Air Header Tag Number
  • Type of Instrument Air Header installed
  • Location of the air header
  • List of Instruments Connected to air header

Instrument Bill of Material

A Bill of Material (BOM) is a complete inventory of all the parts that comprise an object or assembly, it is also a component of material requirements planning (MRP). 

The Instrument Bill of Material is primarily used to determine the quantity of each item required for a project. It displays all necessary supplies and pricing for project engineering and assists in calculating the project’s budget.

Instrument Logic Diagrams

An Instrument Logic Diagram’s main objective is to establish how a particular system or component functions when input signals change. 

The logic diagram’s purpose is to assist technical design, operation, and maintenance experts involved with the systems in understanding how the process works, so that the system engineer can properly implement the logic in PLC/DCS systems.

Control Narrative

A system control philosophy is a document that contains a description of the operating philosophies prepared by process engineers. 

The Control Narrative describes the control philosophy as well as the variables in the control program. Field instrument parameters, pumps, valves, and other process equipment status signals are examples of variables.

Cause & Effect Drawings

The Cause and Effect diagram offers information about different causes and their trip effects on the field equipment.

This document is mostly used in Emergency Shutdown (ESD) and Fire & Gas System (FGS) to identify various causes and their associated trips in a matrix style for better and simpler interpretation.

Causes can include a change in the state of a digital input, a High High/Low Low alarm from an analogue input, and interlock logic, among other things. Effects can include tripping a motor or pump, closing a valve, opening a pressure relief valve, activating an emergency alarm, Beacon/Hooter, and so on.

SAMA drawing

SAMA diagrams are commonly used in the process industry and are based on the symbols and diagramming rules defined by the Scientific Apparatus Manufacturers Association (SAMA).

A SAMA diagram includes a number of enclosing symbols that describe various features or operations of the control system. 

Rack room layout diagram

A rack room layout diagram is a two-dimensional elevation drawing that depicts the arrangement of control system cabinets like system cabinet and Marshalling cabinet inside the rack room. It is usually a scaled design that represents the overall floor diagram of the rack room with elevations.

Control Room Layout

A control room layout diagram is a two-dimensional elevation design that shows how the centralized operator monitoring consoles, as well as various Auxiliary consoles such as Maintenance Override Switch (MOS) consoles and Public Announcement (PA) System are organized. It is usually a scaled design that represents the overall floor diagram of the control room with elevations.

Cabinet Layout – GA/IA drawing

Cabinet layout describes how the components within and outside of any control or electrical panel are organized.

Cabinet layout includes two primary drawings, as stated below: 

General Arrangement Drawing (GA), which illustrates how components are arranged outside of a control or electrical panel, as well as their specific dimension, weight, make, and model details.

Internal Arrangement Drawing (IA), as the name implies, illustrates how components are arranged or installed within a control or electrical panel, as well as their position, tagging, and wiring details.

Single line diagram

The simplest kind of symbolic representation of an electric power system is known as a single-line diagram (SLD), which is also sometimes referred to as a one-line diagram.

The single-line diagram provides specific information regarding the facility’s electrical distribution system’s layout as well as its design.

IP Address Schedule

An IP address schedule refers to a planned allocation or assignment of IP addresses to devices or networks. It helps ensure efficient management and organization of IP resources, facilitating proper network configuration and troubleshooting.

Refer the link for Detailed Explanation of IP Address Schedule

Network switch port allocation details

Network switch port allocation details refer to the assignment and management of ports on a network switch. It involves designating specific ports for connecting devices, such as computers, servers, or other networking equipment. Proper port allocation helps in organizing network traffic and ensuring efficient communication between devices.

Refer the link for Detailed Explanation of Network switch port allocation details

Network Equipment list

A network equipment list is a comprehensive inventory of networking devices deployed within a network infrastructure. It includes items such as routers, switches, firewalls, access points, and other network components. The list provides crucial information about each equipment’s specifications, location, and configuration, aiding in network administration and troubleshooting.

Refer the link for Detailed Explanation of Network Equipment list

Marshalling Cabinet drawing and its significance

A marshalling cabinet drawing is a technical illustration or diagram that depicts the layout and arrangement of a marshalling cabinet. It provides details about the cabinet’s dimensions, compartments, cable routing, and connections. These drawings are essential for proper installation, maintenance, and organization of electrical or communication equipment within the cabinet.

Refer the link for Detailed Explanation of Marshalling Cabinet drawing and its significance

I/O Database

An I/O (Input/Output) database is a centralized repository that stores information about the inputs and outputs of a control system or industrial process. It contains details about connected devices, signal types, addresses, scaling parameters, and other relevant data. The I/O database aids in configuration, monitoring, and troubleshooting of the system’s inputs and outputs.

Refer the link for Detailed Explanation of I/O database

System Architecture

Control system architecture in the process industry involves the design and arrangement of components and subsystems that regulate and monitor industrial processes. It includes sensors, actuators, controllers, and communication networks, ensuring efficient and reliable operation, safety, and optimization of processes such as manufacturing, refining, and power generation.

Refer the link for Detailed Explanation of System Architecture

Earthing Drawing

An Earthing Drawing, also known as an Earthing System or Grounding Diagram, is a schematic representation illustrating the electrical grounding arrangement of a building or installation. It shows the connection of electrical equipment and structures to the Earth to ensure safety and protect against electrical faults and lightning strikes.

Refer the link for Detailed Explanation of Earthing Drawing

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