Basic Safety and General Consideration While Executing Calibration Process in process industries

List of documents required for carrying out calibration process

There are a variety of documents that may be required for carrying out the calibration process in a process industry setting. Some common examples include:

  1. Work Order
  2. Job Risk Assessment
  3. Isolation Procedure
  4. Calibration procedure
  5. Calibration record
  6. Calibration certificate
  7. Maintenance record
  8. User manual
  9. Instrument loop diagram or wiring diagram
  10. Instrument Datasheet
  11. Quality management system documentation

1.Work Order:

work order

In a process industry, a work order is a document that describes a specific task or set of tasks that need to be completed. A work order may be used to request maintenance, repairs, or other work on equipment or facilities. It may also be used to request calibration of instruments or other types of testing or inspection.

A work order typically includes information such as the date the work is requested, a description of the work to be performed, the location of the work, the equipment or facilities involved, and any special instructions or requirements.

It may also include an estimate of the time and resources required to complete the work, and the name of the individual or team responsible for completing the work.

Work orders are often used to track the progress of work and to ensure that tasks are completed in a timely and efficient manner. They may also be used to generate reports and metrics on the work performed in a process industry setting.

In other words the work order can also be referred as Work Permit or Permit to work in process industries.

2. Job risk assessment:

Job risk assessment 1
job risk assessment 2

Job risk assessment is the process of identifying and evaluating the risks associated with a specific job or task. The purpose of a job risk assessment is to identify potential hazards and assess the likelihood and severity of harm that could result from those hazards.

It is an important tool for helping to ensure the safety and health of workers who will be involved in the calibration activity in the process industry.

It’s important to regularly assess the risks associated with each step in the instrument calibration process and take appropriate precautions to mitigate those risks. This can help to ensure the safety of the technicians performing the calibration and the accuracy of the calibration results.

3. Isolation Procedure:

isolation procedure

An isolation procedure is a set of steps that are followed to safely isolate an instrument from a process or system in a process industry.

The purpose of an isolation procedure is to ensure that the instrument can be safely accessed, worked on, or removed for calibration without disrupting the operation of the process or system.

An isolation procedure typically includes the following steps:

  1. Identify the instrument to be isolated
  2. Identify the process or system that the instrument is a part of
  3. Identify the hazards associated with the isolation
  4. Develop an isolation plan
  5. Communicate the isolation plan
  6. Isolate the instrument
  7. Confirm isolation

It is important to follow an isolation procedure carefully to ensure the safety of personnel and the integrity of the process or system.

4. Calibration procedure:

This document outlines the steps and procedures that should be followed when calibrating an instrument. The procedure may include information on how to set up the instrument, how to perform the calibration, and how to record and document the results.

In other words this document can also be referred as Method Statement to perform an Instrument calibration.

5. Calibration record:

This document is used to record the results of the calibration process. The record should include the name of the instrument being calibrated, the date of the calibration, the results of the calibration, and any corrective action taken if necessary.

6. Calibration certificate:

This document is issued by a calibration laboratory or other qualified organization to certify that an instrument has been calibrated to a specific standard or specification. The certificate should include the name of the instrument, the date of the calibration, and the results of the calibration.

7. Maintenance record:

This document is used to track the maintenance and repair history of an instrument. The record should include the name of the instrument, the date of maintenance or repair, and a description of the work performed.

8. User manual:

This document provides information on the operation and maintenance of an instrument. The manual should include instructions on how to use the instrument, how to perform routine maintenance, and how to troubleshoot common problems.

9. Instrument loop diagram or wiring diagram

An instrument loop diagram, also known as a wiring diagram, is a diagram that shows the interconnection of process control instruments and devices used in a process industry.

This diagram typically contains below details of the instrument to be calibrated:

  • The location of the instruments.
  • Wiring that connects them.
  • Function of the instrument.
  • Type and size of wiring used.
  • Type of connectors.
  • Electrical characteristics of the instrumentation.

10. Instrument Datasheet

An instrument datasheet is a document that provides technical information about a specific instrument or device used in a process industry.

This datasheet typically contains below details of the instrument to be calibrated:

  • Make and model of the instrument.
  • Operating range and accuracy.
  • Electrical characteristics such as voltage, current, and power requirements.
  • Environmental considerations, such as temperature and humidity range.
  • Dimensions and weight of the instrument.
  • Safety considerations, such as any hazardous materials used in the instrument.
  • Approvals and certifications.
  • Vendor or manufacturer contact information.
  • Other relevant technical data.

11. Quality management system documentation:

In some cases, an organization may have a quality management system (QMS) in place to ensure the quality of its products and services. The QMS may include documents such as quality policies, procedures, and standards that apply to the calibration process.

Tools required for carrying out calibration process

There are a variety of tools and equipment that may be used for instrumentation calibration in the process industry.

Some common examples include:

  1. Calibrators
  2. Multimeters
  3. Oscilloscopes
  4. Data Acquisition Systems
  5. Reference Standards
  6. Test Leads and Probes

1. Calibrators:


These are devices that are used to accurately measure and adjust the output of an instrument. Calibrators can be used to test and calibrate a wide range of instruments, including pressure gauges, temperature sensors, and flow meters.

2. Multimeters:


These are handheld devices that can measure a variety of electrical quantities, such as voltage, current, and resistance. Multimeters are often used to test and calibrate electrical instruments, such as transmitters and sensors.

3. Oscilloscopes:


These are electronic test instruments that are used to display and analyze electronic signals. Oscilloscopes are commonly used to troubleshoot and calibrate electronic instruments.

4. Data acquisition systems:

These are computer-based systems that are used to collect, store, and analyze data from a variety of instruments and sensors. Data acquisition systems are often used to perform comprehensive instrumentation calibration in process plants.

5. Reference standards:

Reference standards

These are devices that are used to establish a known, accurate measurement for comparison purposes. Reference standards may include pressure gauges, temperature sensors, or flow meters that have been calibrated to a high degree of accuracy.

6. Test leads and probes:

test leads and probes

These are electrical connectors and probes that are used to connect instruments to calibrators or other test equipment. Test leads and probes come in a variety of shapes and sizes to accommodate different types of instruments and connectors.

Above given are some of the examples of tools required, this may vary depending on instrument which has to be calibrated, so refer calibration procedure to understand the tools required to perform calibration.

Before going to filed make sure adequate tools with valid calibration report is available.

Calibration flow

Calibration process

Preparation and data record

  1. Make sure the working environment is safe.
  2. Obtain permit to work from designated authority with necessary above documents.
work permit
  1. Display caution, bypass and warning notices on the control room.
caution notice
  1. Observe all safety precautions and communicate with other crew members in the same area about the calibration activity.
  2. Refer relevant drawings and documents.
  3. Collect all test standards and tools required for necessary check-up/testing and calibration.
  4. Verify the calibration validity of the test standards used for calibration.


1.Verify the interlocks and do maintenance override on the instrument or from engineering system/maintenance mode in operator console.

2. Isolate the equipment.

lockout box
isolation padlock

3.Barricade the work area if required.

Barrication of work area

4. Identify and locate the instrument with tag number which is under calibration.

5. Prior to carrying out measurements, clean the Instrument and allow it to stabilize with the environment.

6. Instrument must be switched ON and allowed to warm up as per manufacturer’s recommendation.

7. Write all the specification or the technical data available on the nameplate of the instrument i.e.. tag number, serial number, span calibration range and model number. etc.

instrument name plate setails

8. Confirm and adjust (where applicable) zero indication on the instrument  and verify it with operating console in the control room.

9. Do the calibration as per instruction on the calibration procedure and the instrument reference manual.

Calibration process

10. Apply input corresponding to 0 %, 25 %, 50 %, 75 % and 100 % according to the range of Instrument in the upscale and downScale direction from the test standards.

11. If the result of the output value is not within an acceptable limit, then calibration must be performed. All the output values are within acceptable limits (+/- %), then further calibration is not required.

12. Record the resultant output values in the as found column of blank calibration report.

13. Place calibration label on instrument once the calibration was satisfactorily done. The calibration label or sticker must have at least following data:

  • Tag number
  • Calibration date
  • Calibration due date.
calibration ok label

14. In order to avoid unauthorized adjustments to inspection, measuring, and control instrument with adjustable devices whose settings can affect performance, they must be sealed or otherwise safeguarded after calibration. Seals must be made so that tampering is easily visible.

15. An instrument will not be recognized as conforming if

  • It has been handled carelessly or improperly.
  • It displays any malfunctions beyond the tolerance.
  • It has gone beyond the designated confirmation interval.
  • There has been a breach in the seal’s integrity.

If any of the above-mentioned non-conformances occur, the instrument must be taken out of operation, separated, and marked or labeled prominently.

failed calibration label

Completion of calibration

  1. Once the calibration is completed, ensure that all test standards, monitoring and measuring equipment and devices should be reinstalled to their designated field location or returned to their respective places or designated area.
  2. Ensure that the calibrated instrument is in safe and operable condition after completion of calibration work.
  3. Do the proper housekeeping in that work area.
  4. De-isolate the equipment.
  5. Normalize the bypassed/inhibited signal.
  6. If the work area was barricaded, remove the barricading.
  7. Remove the signboard from the operating console at control room.
  8. Ensure work site is left in a clean/safe condition.
  9. close work permit and inform operation about completion of work.

Calibration report documentation

  1. Upon completion of calibration, instrument calibration certificate is to be completed by the instrument technician and the following details must be completed on the Equipment Calibration certificate for each piece of equipment:
  • Serial number of the instrument
  • Tag number and CMMS or SAP number if applicable.
  • Description (type of instrument).
  • Make (manufacturer’s name)
  • Model number or type of  instrument
  • The instrument serial number
  • The frequency of the calibration
  • The calibration validity of the test standards used for the calibration
  • The last calibration date and next due date of the instrument
  • The calibration certificate number of test standard
  • Authorized required signatures
sample calibration report
  1. On the same day of calibration, the calibration certificate should be forwarded to the calibration responsible engineer for validation of the test results.
  2. The calibration-responsible engineer, upon satisfaction of the test result, must sign the appropriate column in the calibration data report and update the work order.
  3. After the completion of the calibration process, The calibration data needs to be updated in the calibration history file with below data from the calibration process.
S.No.Tag .NoWork order no from CMMS or SAPDescription of the instrumentMakeModelSerial No. of the instrumentFrequency of the calibrationAcceptable limit in %Calibration statusRemarks
Cal. DateCal. due

Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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