Substantial Modification - When Does a Modification Become “Substantial”?

Substantial modification - when does a modification become "substantial"? 

When a machine is modified during its lifetime, it is important to keep track of whether the modification is considered substantial or not. Documenting modifications and carrying out a structured assessment not only creates control but also increased awareness of how the changes affect the machine’s safety.

An important parameter to keep in mind when modifying machinery is that it is not the amount of things you change that determines this - it is how safety is affected.

The Machinery Regulation clarifies this significantly more than the previous Machinery Directive.

In this article, we go through what a substantial modification means according to Article 3(16), how the modification needs to be assessed, and what happens if the criteria for a substantial modification are met (which means that Article 18 becomes applicable).

The articles in their entirety can be found below the FAQ section. 

What is a substantial modification?

Article 3, (16) of the Machinery Regulation defines substantial modification as a physical or digital modification of machinery or a related product that is made after it has been placed on the market or put into service.

The modification must be something that the manufacturer has not foreseen or planned for, and it must be capable of affecting the safety of the machinery by creating a new hazard or increasing an existing risk.

This is where the assessment becomes more concrete. If the modification creates a new hazard or increases an existing risk, it is necessary to assess how the changed risk situation is to be managed.

The question is therefore not only which protective measures have actually been installed, but which protective measures are required as a result of the modification.

According to Article 3.16, this includes situations where the modification requires:

a) the addition of guards or protective devices to the machinery or related product, where the addition makes it necessary to modify the existing safety control system,

or

b) the implementation of additional protective measures to ensure the stability or mechanical strength of the machinery or related product.

This means that when making the assessment, it is necessary to consider the changed risk situation and which protective measures result from the modification – not only focus on which measures have actually been implemented.

What does this mean in practice?

A modification can change the machine’s risk situation.

For example, a machine may:
-have a higher speed,
-have greater force,
-have changed movements,
-have increased access to a hazardous area,
-have changed control or safety logic,
-be used in a different way than before.

Such changes can create a new hazard and/or increase an existing risk.

In practice, this means, among other things, that it is necessary to investigate whether existing guards and protective measures can still manage the changed risk situation, or whether the modification creates a need for new or additional protective measures.

Guidance will be important

There are still parts of the application of the rules on substantial modification that may require further guidance.

The European Commission’s Guide to the Machinery Regulation is currently being developed, and the work covers, among other things, the new and updated requirements in the Machinery Regulation.

Until the guide is published, it should therefore be clearly distinguished between what is expressly stated in the Regulation and practical interpretations of how the provisions are to be applied.

This is particularly important when assessing whether a modification affects a machine’s risk situation.

Let's look at "higher speed" as an example

Let us assume that a machine is modified so that a moving part operates at a higher speed. This may mean that an existing risk increases or that new risks are introduced.

We then need to assess how the changed risk situation affects safety and which protective measures are required as a result of the modification.

If the increased risk means that new guards or protective devices need to be introduced, we also need to assess how these affect the machine’s existing safety control system.

If the new guards or protective devices mean that the existing safety control system must be modified, this is the situation described in Article 3.16(a).

Similarly, a modification that affects the machine’s stability or mechanical strength may mean that additional protective measures are required under Article 3.16(b).

It is therefore not the size of the modification itself that is decisive. It is how the modification affects safety and what consequences this has for the machine’s guards and safety measures.

The Risk Assessment

The risk assessment is central when assessing a modification.

It is necessary to identify what has changed and how the change affects the machine’s risk situation.

Examples of questions to consider:
-Has the machine’s function or performance changed?
-Have speed, force, movement or other machine parameters changed?
-Has access to hazardous areas changed?
-Has a new hazard arisen?
-Has an existing risk increased?
-Are existing guards and protective measures still sufficient?
-Does the modification require new guards or protective devices?
-If guards or protective devices need to be added - do we need to modify the existing safety control system?

Are additional protective measures required to ensure stability or mechanical strength?

Here you can read more about how to carry out a risk assessment -> Risk Assessment in 5 Steps -> Risk assessment in 5 steps

A practical path through the assessment

Article 3.16 can be used as a starting point for the assessment:

Step 1. Has the machinery or related product undergone a physical or digital modification after it was placed on the market or put into service?

Step 2. Was the modification foreseen or planned by the manufacturer?

Step 3. Does the modification affect safety by creating a new hazard or increasing an existing risk?

Step 4. Assess the risk situation (has it changed, have new risks been introduced)?

Step 5. Are existing guards and protective measures sufficient? Or does the modification mean that:

A. guards or protective devices need to be added, making it necessary to modify the existing safety control system,

or

B. additional protective measures are required to ensure stability or mechanical strength?

If the criteria in Article 3.16 are met, this means that we have a substantial modification.

Okay, so what happens if we have actually carried out a substantial modification?

This is where Article 18 comes in.

The person who carries out a substantial modification assumes manufacturer responsibility for the affected machinery or related product. The person or company is then considered to be a manufacturer under the Machinery Regulation and is subject to the manufacturer’s obligations under Article 10.

This means, among other things, that the person who carried out the modification must ensure and, on their sole responsibility, declare that the affected machinery or related product complies with the applicable requirements of the Machinery Regulation, and apply the relevant conformity assessment procedure in accordance with Article 25.2, 25.3 and 25.4.

In other words - you are considered a manufacturer and must therefore carry out the relevant conformity assessment, prepare an EU Declaration of Conformity and CE mark the affected machinery or related product again.

If the modification concerns part of an assembly of machinery

Article 18 makes an important distinction for assemblies of machinery.

If the substantial modification only affects the safety of machinery or a related product that constitutes part of an assembly of machinery, the manufacturer’s obligations apply to the affected machinery or related product, in accordance with the risk assessment.

To carry out this assessment, it may therefore be important to have access to the original risk assessment and information about the machine’s existing guards and safety functions.

This does not therefore automatically mean that the entire assembly of machinery is subject to manufacturer responsibility as a result of a modification to an individual part.

Exemption for non-professional users

There is also an explicit exception in Article 18.

A non-professional user who carries out a substantial modification to their machinery or related product for their own use shall not be considered to be a manufacturer under the Machinery Regulation and shall not be subject to the manufacturer’s obligations under Article 10.

Digital modifications are also covered

A substantial modification does not necessarily mean that physical parts of the machine are rebuilt or replaced. Article 3.16 expressly covers modifications made by physical or digital means.

This means that a digital modification may also need to be assessed according to the same criteria as a physical modification. The decisive factor is not that the modification takes place in the software, but how the modification affects the machine’s safety and risk situation.

This may, for example, involve changes to:
-control and control logic
-safety functions
-speeds or movement parameters
-limitations or monitoring
-functions that affect access or the machine’s behaviour

A software modification is therefore not automatically a substantial modification. It needs to be assessed based on the criteria in Article 3(16).

Foreseen or planned by the manufacturer

Article 3.16 states that the modification must be one that the manufacturer has not foreseen or intended.

The question is therefore not only what has changed and how safety is affected, but also whether the modification is something that the manufacturer has foreseen or intended.

At the same time, it is important not to confuse this with the question of what the manufacturer could have foreseen. The Regulation uses the wording that the modification must not have been foreseen or intended by the manufacturer, and it is this wording that we should base our assessment on.

In uncertain or difficult cases, this therefore needs to be considered together with the other criteria in Article 3.16.

Documentation and conformity assessment

When a modification is a substantial modification, questions arise regarding, among other things, technical documentation and conformity assessment.

We cover these areas in more detail in our separate article:
CE marking of machinery - requirements, process, and technical documentation

Summary

When a machine is modified, the most important question is how the modification affects safety – not how extensive the modification itself is.

A substantial modification according to Article 3.16 can be physical or digital and means, among other things, that the modification affects safety by creating a new hazard or increasing an existing risk. The next step is to assess which protective measures are required as a result of the modification and whether the conditions in Article 3.16(a) or (b) are met.

If the modification is assessed as a substantial modification, Article 18 becomes applicable. The person who carried out the modification is then considered to be a manufacturer and thereby assumes manufacturer responsibility for the affected machinery or related product.

It is therefore important to document modifications, carry out a structured risk assessment and be able to demonstrate how the changed risk situation has been managed.

This is, of course, carried out easily, quickly and step-by-step with guidance for users in the Noex platform.