Understanding ISO 9001 Calibration Requirements -Calibration Clauses Explained

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Almost all industries used monitoring and measuring equipment to manufacture products or support services, it is required that this equipment must be calibrated in order to ensure that the intended product specification is achieved. In short, quality is maintained when calibration is performed.

ISO 9001 is the quality management system designed for manufacturers (producers of products) or service providers. There are other more specific standards for specialize industries like automotive, pharmaceuticals or Oil and Gas but ISO 9001 is still integrated with them.

For a calibration process to be properly implemented, there should be in-house calibration management that we should follow.

What is calibration and why do we need calibration? Visit my other post in this link >> calibration awareness

This calibration management is guided by ISO 9001: 2015 Standards which has dedicated clauses that detail the requirements needed for proper implementation.

In this article, I will share with you:

1.       The related clause of ISO 9001 that are focused mainly on calibration requirements.

2.       ISO 9001 Calibration procedure – The content of a calibration procedure

Read on…

ISO 9001 Calibration Requirements

What are the Calibration requirements of ISO 9001? Below are the related clauses where calibration requirements are provided. These clauses that I  listed here are the clauses with calibration requirements that are directly affecting the calibration results, these are:

1.       Clause 7.1.2 People

2.       Clause 7.1.4 Environment for the operation of processes

3.       Clause General monitoring and measuring requirements

4.       Clause Measurement traceability

5.       Clause 7.2 Competence

6.       Clause 9.1.1 General requirements for monitoring, measurement, analysis, and evaluation

These are the calibration requirements as per my experience, you may include other clauses you know that are directly affecting the calibration results.

Clause 7.1.4 Environment for the operation of processes

This clause requires the monitoring and control of the environment for the correct performance of calibration. Same with ISO 17025 requirements, environmental conditions that influence the final output of calibration results should be monitored and controlled.

Some examples of environmental conditions that we need to monitor and control are:

1.       Temperature

2.       Humidity

3.       Vibrations

4.       Dust

5.       Proper lighting

6.       Airflow

Not all listed above needs to be controlled simultaneously inside a lab. This depends on the criticality and the effect it can contribute to the calibration performed.

But mostly, the two environmental conditions that are always controlled are temperature and humidity because almost all instruments require it for proper functioning, it is detailed in their specifications.

Clause 7.1.5. monitoring and measuring requirements

Instruments that we use to perform measurements are considered monitoring and measuring instruments.

“It is either we perform a measurement to monitor and control a process or we perform measurement for verification of the output of our process.”

With this in mind, all the instruments that are used for monitoring and measurement should be controlled.

The control provided are:

  1. The instrument to be used should be suitable. Suitable means it covers the range and accuracy requirement. For every monitoring and measuring instrument we use, we should ensure that the usable range can be covered and as much as possible, it has higher accuracy than the process to be measured. Recommended is to maintain the Test Uncertainty Ratio (TUR) of 4:1.
calibration label and seal

2. Every monitoring and measuring instrument should be maintained to ensure confidence while using or within its calibration interval. Maintained means:

a.       Properly monitored for its statuses like locations, labels, and calibration due dates.

b.       Preventive maintenance is performed

c.       Intermediate check is performed.

Records of Implementation of the above requirements should be maintained that can be used as evidence of implementation during audits.

Check out this link to read more about monitoring and measurement >> Applications of Monitoring and Measurements

Clause Measurement traceability

We should ensure measurement traceability for every monitoring and measuring instrument used. It is a requirement that is a must to follow to ensure confidence in the validity of measurement results.

There are 2 ways where we can implement Measurement Traceability requirements, these are:

1.       Establishing traceability

2.       Maintaining traceability

Establishing Traceability

calibration traceability
Traceability Chain with pyramid

Let us define first Traceability. As per VIM 3 clause 2.41, Traceability or Metrological Traceability is “Property of a measurement result whereby the result can be related to a reference through a documented unbroken chain of calibrations, each contributing to the measurement uncertainty”.

The definition above is about establishing Traceability, wherein the measurement result of our instruments should be linked or connected through an unbroken chain of calibrations all the way to SI.

In establishing traceability under ISO 9001, we use clause stating that,

(a) “all monitoring and measuring instruments shall be calibrated or verified, or both, at specified intervals, or prior to use, against measurement standards traceable to international or national measurement standards”.

The traceability of your instruments will be established when calibrated, verified or both prior to use, by a higher laboratory that is linked to international standards or SI.

To ensure traceability, such laboratories should be accredited under ISO 17025. Traceability can also be established by using a Certified Reference Material or CRM provided by a reputable source.

Check out the difference between calibration and verification in this post >> How to Differentiate Calibration and Verification

Maintaining Traceability

After the successful establishment of traceability, the most challenging part is now to maintain traceability.

Activities that support the maintenance of traceability are the following which is the 2 remaining sub-clauses of these are:

(b) Identified in order to determine their status

Identification through labeling and coding of measuring instruments in order to monitor their status. Labels include a clear detail of its calibration due date, date of calibration, and who performs the calibration.

Status means their present location, calibration interval, calibration condition (within tolerance), and specific records that detail their performance and specifications.

(c) safeguarded from adjustments, damage or deterioration that would invalidate the calibration status and subsequent measurement results.

Safeguarded from adjustments using void seals and safeguarded from damage or deterioration by implementing procedures for proper handling, transport, and storage while it is being used for measurement and/or calibration.

UUT with equipment ID and void seal
UUT with equipment ID and void seal

When measuring equipment is found to be unfit for its intended purpose, appropriate actions shall be taken like:

1.       recalibration,  

2.       adjustment and verification

3.       adjustment of the calibration interval

4.       proper disposition – scrap or reject

Read more about the deeper meaning of traceability in this link >> Traceability

Clause 7.2 Competence

As defined from ISO 19011 competence is: “demonstrated personal attributes and demonstrated ability to apply knowledge and skills “.

Clause 7.2 and 7.1.2, which is about People are related to each other.  ISO 9001 clause 7.1.2 requires that “The organization shall determine and provide the persons necessary for the effective implementation of its quality management system and for the operation and control of its processes.”

In relation to calibration, the People, which are the personnel involved in performing calibration should be competent or have the necessary competency.

Personnel Competency is one of the main requirements that we must meet. All factors that influence the quality of calibration performed depend on the knowledge, skills, experience, and education of Personnel.

You may have a high-end calibrator, a good calibration procedure, and a well-equipped facility but the person in charge is not suitable for the calibration activity performed, then the calibration results may be invalidated.

To be competent means:

1.       Has the necessary competence requirements such as appropriate education, training, or experience;

2.       Pass the competency evaluation

3.       Authorized to perform important laboratory activities

4.       Monitored competency and continued education

All the records and recorded information resulted from this process should be maintained and used as evidence of competency.

 I discussed more about ‘personnel competency’ in my other post here >> Personnel Competency

Clause 9.1.1 General requirements for monitoring, measurement, analysis, and evaluation

This clause is composed of many processes or activities that involve monitoring, measurement analysis, and evaluation. But in this article, we will just focus on the requirements related to calibration.

In these requirements, we need to determine:

1.       What needs to be monitored and measured.

We need to monitor our measuring instruments and measure or perform verification on the measurement results or displayed output.

We need to monitor measuring resources to be able to control and properly maintained and ensure the validity of results every time they are used.  Monitoring is easily implemented by having a master list of all the measuring instruments and standards that details their important information and specifications including their calibration records.

2.       The methods for monitoring, measurement, analysis and evaluation needed to ensure valid results;

We need to have a procedure for quality control like performing recalibration, intermediate check, calibration interval adjustment, or verification and validation to ensure traceability and valid results are maintained. We can use statistical techniques like control charts or a simple checklist and tables to analyze and evaluate each performance.

3.       When the monitoring and measuring shall be performed;

All the methods or procedures for quality control stated in number 2 (above) should have a specific schedule of implementation. For example, for Temperature and humidity, a schedule of 3 times a day is given. Another example is the Intermediate check which is performed every 3 months alongside preventive maintenance. This will ensure regular or periodic implementation to maintain the quality and confidence of results.

4.       When the results from monitoring and measurement shall be analysed and evaluated.

Every time we implement the quality control procedures of number 3 above, we can gather the data then immediately subject to analysis and evaluation.

Another example of analyzing and evaluating measurement results is during the receipt of a newly issued calibration certificate. There should be a process in place on how to review or evaluate a calibration report.

Mostly, we are looking for any out-of-specification condition or a trend that shows us something is wrong or will become an issue in the future. If any issues were found, corrective or preventive action will be issued and proper action is taken.

Other Calibration Requirements

The clauses that I identified above are the main clauses that have an impact on the calibration results and are directly calibration implementation requirements in my understanding.  There are other clauses that are still calibration-related but do not directly impact the results of calibration and are mostly under Quality.

Such as:

1.       Internal audit – auditing the calibration process

2.       Document and records control – controlling documents and records like calibration procedures, calibration certificates and datasheets.

3.       Risk and opportunities – Identifying risk and opportunities from calibration activities to improve and mitigate any issues found.

4.       Improvements – performing improvement activities to further improve the calibration processes like equipment upgrades, regular trainings or monthly meetings.

5.       Complaints or Customer survey – customers are the users of instruments, it is important to document their concerns for improvements.

Overall, the requirements of ISO 9001 will provide a complete implementation to support the proper operation of an Internal Calibration Laboratory. But we need to have a deeper understanding of all the calibration requirements in order to properly manage a calibration Lab.

ISO 9001 standards do not provide the exact Instruction to manage a calibration lab, just a general requirement. If you want in-depth Calibration Laboratory management guidelines, you need to be familiarized with ISO 17025 Standards, this is the main standards for calibration and testing lab, specifically if you want to provide services to other clients or industries.

Do you want a guide in implementing In-house Calibration? Check out my other post here>> Elements In Implementing an Internal Calibration Laboratory

ISO 9001 Calibration Procedure

If will share here ISO 9001 calibration procedure, also known as calibration method, which is referring to an Internal calibration procedure use to execute actual calibration of instruments for in-house or internal calibration lab.

I have seen a number of calibration procedures from different calibration labs and I can tell you that every company has different formats.

There are no exact requirements for the formats of a calibration procedure that I am aware of, most available formats are just recommendations. I believe it is based on the company policy and the experience or expertise of the Calibration engineer who created the calibration procedure.

There are some instances that a calibration procedure for ISO 9001 is very simple, where it is integrated into the procedures of preventive maintenance or equipment operation manual.

There are also calibration procedures that are ‘generic’, which means it is applicable for many types of instruments.

But regardless of either ISO 9001 or ISO 17025 calibration procedure, before we will use it, we must consider the important calibration procedure requirements, it should be:

1.       Verified or validated before use.

2.       It has traceability; there is a reference to where it came from and who created it.

3.       Approved before use

4.       Up to date – the latest version is used

5.       Controlled- included in Document and Records Control 

Content of a Calibration Procedure

If you are planning to create or prepare an ISO 9001 calibration procedure or calibration methods, the following are the calibration procedure content, as a minimum, that I am aware of.

These can be used as content of a calibration procedure template.

These are:

1. Purpose – state the reason why we have the calibration procedure

2. Scope–to what instruments does the procedure applies for including the range if necessary. (sometimes purpose and scope are the same).

3. Terminology – includes here the terms or acronyms used in the procedure that we need to define.

4. Safety–detailed here the possible safety hazards and their avoidance including any safety documents that need to follow or accomplish before performing calibration.

5. Reference Standard Used–describes all the reference equipment used for calibration for traceability and accuracy evaluation.

6. Other Materials/Tools – includes all other supporting materials or tools to perform the calibration/test activity.

7. Reference Document Use–these are the reference documents where the procedure was based during write-up or drafting. Also, a reference to determine the traceability of the procedure used.

8. Initial requirements/preparation– as the term implies, any requirements or prerequisites before initiating the calibration/test process. A preparation in order to achieve the best results.

9. Calibration Procedure -Main Steps of procedure Execution, the step-by-step instructions in performing the actual calibration. This includes any calculations or photos to easily describe and understand the procedure.

10. Acceptance Criteria–detailed here is the tolerance limit that needs to be met for verification purposes after performing the calibration.

11.Storage and Handling – describe here where to put the instruments and how it is handled after calibration.

Additional that you can include are:

1.       Responsibility

2.       Summary of Procedure

3.       Not operational conditions

4.       Accuracy and /or Components of Measurement Uncertainty

5.       Calibration Status

6.       Calibration Certificate Content

7.       Correction or Adjustment procedure

8.       General Notes


ISO 9001 Standards is a Quality Management System that is well known and applicable for almost all industries. One of the major requirements under this standard is the implementation of calibration.

Calibration provides quality, reliability, and safety of manufactured products, therefore, it has a dedicated clause focused mainly on implementing the calibration process.

In this post, I have shared the following:

1.       The related clause of ISO 9001 that are focused mainly on calibration requirements.These are:

    •  Clause 7.1.2 People.
    •  Clause 7.1.4 Environment for the operation of processes.
    •  Clause General monitoring and measuring requirements
    •  Clause Measurement traceability
    •  Clause 7.2 Competence
    •  Clause 9.1.1 General requirements for monitoring, measurement, analysis, and evaluation.

2.       ISO 9001 Calibration procedure – The content of a calibration procedure

If you want an in-depth understanding of calibration management and calibration processes, you can use ISO 17025:2017 as the Quality Management System. This Standard is dedicated to testing and calibration laboratories.

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4 Responses

  1. M. saleh AL-Mufti
    | Reply

    Dear Eng. Edwin,
    I’m very grateful for your efforts & kind attention to calibration issues.
    Q., How do I know that the calibration certificate that I issued meets the requirements of specification ISO/IEC 17025: 2017 accurately?
    Thanks in advance.

    • Dear Sir,
      You are welcome, I appreciate the time for reading my posts.

      To answer your concern:
      There are 2 ways to check the content of the calibration certificate, 1st is to check the requirements of a calibration certificate and 2nd is to check the requirements of the customer- the calibration results.
      1. To determine if you covered all the requirements of a calibration certificate, you can use ISO 17025 clause 7.8.2 as a checklist. All the requirements for a calibration report are listed there.

      2. Regarding the calibration results, it is based on the calibration lab procedure and the agreement during contract review or the assessment of customer requirements. This should be documented for example, on the Quotation or purchase order (PO), sometimes, there is a customer request form.

      The key here, in order to meet the specifications accurately, is to have a quality person that is familiar with the standards (ISO 17025). He/She is the authorized person to review and check all the requirements prior to issuing the calibration report.

      You can read more about calibration certificates in my other posts here >> How to Properly Use and Interpret an ISO 17025 Calibration Certificate

      Thanks and regards,

  2. M. Saleh
    | Reply

    Thanks for your reply.

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