List of Instrumentation Project Engineering Documents

Preparation of instrumentation documents is one of the major roles of an instrumentation design engineer. In this article, we are going to discuss various kinds of instrumentation documents used for project engineering.

Piping & Instrumentation Drawing

A Piping & Instrumentation Diagram or P&ID is a schematic illustration of the functional relationship of piping, instrumentation, and system equipment components.

P&ID shows all of piping including the physical sequence of branches, reducers, valves, equipment, instrumentation & control interlocks.

Audit of P&ID is to be done for proper indication of instrument symbols with respect to standard company legends or as per ISA standard.

Audit of P&ID is to be done for proper indication of instrument tag numbers as per the numbering philosophy.

Audit of P&ID is to be done for proper indication of instrument loop with interlocks.

Sample Piping and Instrumentation Drawing

Process Datasheet

This is the most important information require by Instrument Engineer to design various instrument loops according to the services

Data needed by the Instrument Engineer shall be the properties of various components used in the process ( Liquids & Gases) and these are taken from the process datasheet.

The main data included in a process datasheet is as follows.

  • Fluid Name
  • Density / Viscosity
  • Pressure
  • Temperature
  • Flow

The minimum, maximum & operating range of pressure ,temperature & flow has to be mentioned in a process datasheet.

Process Datasheet

Instrument Index

Instrument Index is made for listing all the instruments loop-wise on the basis of P&ID.

It covers all the required information of the instruments in the loop.

The major data that must include in an Instrument Index are

  • Tag Number
  • Description of the Instrument
  • Service
  • Type of Instrument
  • Location of Instrument
  • P&ID Number
  • Instrument Specification Number
  • Hook-up Diagram Number
  • Instrument Layout Number
Instrument Index Document

I/O List

I/O List is used for defining the type of signal inputs & outputs of the instruments used.

It is mainly used for defining the number & types of signals given to PLC / DCS.

It is the basic document used for sizing PLC / DCS.

The main data that must include in an I/O List is as follows.

  • Instrument Tag  Number
  • Service
  • Signal Type
  • Signal Level
  • Instrument Range
  • P&ID Number
Input Output (IO) List Document

Instrument Specification

Instrument Specification documents are made with the help of both P&ID & Process Data.

It helps in specifying the precise requirement of the process for which the instrument is to be used.

Purchasing of an instrument is mainly dependent on Instrument Specification.

The major data that must include in the Specification Sheet is as follows.

  • Tag Number
  • Service
  • Type of Instrument
  • Range
  • Size
  • Location
  • Material
  • Mounting
  • Protection
Instrument Specification Document

Instrument Loop Diagrams

Instrument Loop Diagrams are the graphical representation of loops.

ILDs are made using the help of P&ID, I/O List & Cable Schedule.

ILDs show the detailed flow of signal from instrument to control system cabinet.

The major data that must include in an ILD are;

  • Components used the loop
  • Location of the components
  • Termination details
  • Interlocks used
  • Alarms
  • Soft functions
Instrument Loop Diagrams

Instrument Hook-up Diagrams

Instrument Hook-up Diagrams are the graphical representation of the method of connecting instrument to the process lines, equipment, tanks, vessels, etc.

The main data that must include in a Hook-up Drawing are;

  • Physical mounting of the instrument in the field
  • Various items used for mounting of the instruments
  • Size & material of various items used
  • List of Tag Numbers for which the Hook-up is applicable
DP Flow Transmitter Hook up Diagram

Control Room Layout

Instrument Control Room Layout is one of the important document which gives the idea about location & dimension of different items in the control room.

The main data that must include in the Control Room Layout are;

  • Dimension of the room
  • Entry & Emergency Exit
  • Ventilation & Windows
  • Lighting arrangement
  • Panel Dimension & Location
  • Proper placement of operator console
  • Cable entry
  • Air-lock system
Instrumentation Control Room Layout

Instrument Location Layout

Instrument Location Layout is a document indicating the location & elevation of each instrument, in the plan view.

It gives the location information of the instrument and also to which junction box/air header it is connected.

Instruments mounted on equipment are also shown in this layout with the help of the equipment layout.

Instrument Location Layout

Instrument Tray Layout

Instrument Tray Layout is the drawing that shows the location of junction boxes, instrument air header, local panel & the instrument tray routing in the plan view.

They are made with the guidelines of Instrument Location Layout and thus helps in grouping junction boxes & air headers.

They also show the elevation & number of trays running in tiers in cross-sectional view.

Instrument Tray Layouts are mainly made to show all instrument-related items mounted in the field and are connected to the control room by multicore cables running on instrument trays.

Instrument Cable Tray Layout

Instrument Cable Schedule

A cable Schedule is a document that contains the list of instrument cables.

Each cable should have a precise number according to the numbering scheme.

It is the most important document used for cable laying purpose in project engineering

The main data include in Cable Schedule is as follows.

  • Cable Number
  • Cable Connectivity
  • Type of Cable
  • Length of Cable
  • Size of Cable
cable schedule

Instrument Junction Box Schedule

Instrument Junction Box Schedule is the document that shows all details of the junction boxes information.

Junction Box sizing is mainly dependent on Instrument Junction Box Schedule

The main data that must include in JB Schedule is as follows.

  • Junction Box Number
  • Type of Junction Box
  • Area of Location
  • Instruments Connected
  • Terminal Details
Junction Box Schedule

Instrument Air Header Schedule

Instrument Air Header Schedule is the document that shows all details of the instrument air header and manifolds.

It also shows the air supply route to Instruments.

The main data that must include in Instrument Air Header Schedule is as follows.

  • Instrument Air Header Number
  • Type of Instrument Air Header
  • Area of Location
  • Instruments Connected

Instrument Bill of Material

The main purpose of the Instrument Bill of Material is to quantify various items required for project engineering.

It shows all materials and their costs that are required for project engineering and helps to calculate the budget of the project.

Instrument BOM is the document that mainly covers cable trays, junction boxes, tubes, pipes & fittings, air headers, cable glands, hook-up materials, stanchions, steel required for erection purposes.

The main data must include in Instrument BOM is as follows.

  • Item Description
  • Size of the Item
  • Material of the Item
  • Number of Quantities Required
Instrument Bill of Material (BOM)

Instrument Logic Diagrams

The major function of the Instrument Logic Diagram is to determine the operation of a given component or system as the various input signals change.

The most common use of Logic Diagram is to provide a simplified functional representation of an electrical circuit.

It is easier and faster to figure out how output functions and responds to various input signals by representing a circuit using logic symbols than using the electrical schematic with its complex relays and contacts.

Instrument Logic Diagrams

Cause & Effect Diagrams

Instrument Cause & Effect Document is a tabular chart of functions of various instruments.

This document indicates the cause as an instrument signal in one condition and its effects on other instruments connected in the loop as per the logic.

Cause and Effect Diagrams

Did anything miss from the above list? Share with us through the below comments section.

Author: Greeshmesh TP

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8 thoughts on “List of Instrumentation Project Engineering Documents”

  1. Alarm and trip settings is another document which normally instrumentation team deliver, which I found missing in the list….Worth noting that, certain organizations does not have individual index and I/O list, rather a single document.

  2. Excellent sharing. Would like to know more on open and close loop check commissioning with respect to DCS system I/O modules, input /output modules, SDS system etc…
    Turn over acceptance test after commissioning…. etc Thank you.

  3. Miss an overall connection diagram indicating interconnection between different system such as Fire&Gas, Analyser Systems, ESD system, DCS system etc.

    Missing further is the DCS Functional Block Disgram indicating all aspects of control system which is the basic document for DCS configuration.

  4. Very professional, Very useful to one and all of the instrumentation professionals
    Sir you have kind heart and broad minded and I have no words to describe


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