Modifications to Existing Production Lines

Machinery and production lines that have been CE marked in accordance with Machinery Directive 2006/42/EC may, over time, require modifications, revamping activities or the integration of additional units. Such work is normally carried out to improve efficiency, enhance plant performance or adapt part of the production line to new production requirements.

However, these activities often raise a fundamental question: is the person carrying out the modification required to CE mark the entire production line again

As stated in §39 of the 2023 edition of the Guide to application of the Machinery Directive 2006/42/EC, there are no precise criteria that can be applied in advance to every situation. Each modification must therefore be assessed on a case-by-case basis.

[Guide to application of the Machinery Directive 2006/42/EC – Edition 2.3 of 2023] §39 Assemblies comprising new and existing machinery 

[…] Where, one or more of the constituent units of existing assemblies of machinery may be replaced by new units, or new units may be added to an existing assembly of machinery, the question arises as to whether an assembly of machinery comprising new and existing units is, as a whole, subject to the Machinery Directive. It is not possible to give precise criteria for answering this question in each particular case. In doubt, it is therefore advisable for the person constituting such an assembly of machinery to consult the relevant national authorities.

The main practical situations and their implications are analysed below.

Let us consider a situation in which modifications or additions are made to an existing production line and the subsequent risk assessment demonstrates that the modification:

• does not create or introduce any new hazards; or
• does not increase any existing risks; or
• creates new hazards which are, however, fully mitigated by the protective measures already present on the existing production line.

In such circumstances, the Guide clarifies that no action under the Machinery Directive is required for those parts of the assembly that are not affected by the modification.

[Guide to application of the Machinery Directive 2006/42/EC – Edition 2.3 of 2023] §39 Assemblies comprising new and existing machinery 

[…] If the risk assessment shows that the replacement or the addition of a constituent unit in an existing assembly of machinery does not add a new hazard, nor increase an existing risk, no action is required according to the Machinery Directive for the parts of the assembly that are not affected by the modification. The same applies where there is a new hazard, or an increase in an existing risk, but the existing protective measures present on the assembly before the modification are still sufficient so that the assembly can still be considered safe after modification. […] The employer remains responsible for the safety of the whole assembly according to the national provisions implementing Directive 2009/104/EC

In particular, the Guide expressly states that the integration of an independent, compliant machine which already bears CE marking and is accompanied by an EC Declaration of Conformity does not, in itself, trigger a requirement for a new conformity assessment of the entire production line:

[Guide to application of the Machinery Directive 2006/42/EC – Edition 2.3 of 2023] §39 Assemblies comprising new and existing machinery 

[…] If the risk assessment  for the new unit shows it does not have any safety implications (e.g. by requiring modifications) on the existing assembly and it is a complete machinery that could also operate independently, that bears the CE-marking and is accompanied by an EC Declaration of Conformity, then the addition of this new unit (as a complete machinery) into the existing assembly is to be considered as the installation of the new unit (machinery) and this does not give rise to a new conformity assessment, CE marking or EC Declaration of Conformity for either the new unit (machinery) or the assembly to which is added

Consequently, the following principles apply:

1. No new CE marking of the production line: the person carrying out the modification is not required to CE mark the entire revamped production line again.
2. No action for the unaffected part of the assembly: the pre-existing sections of the production line that are not affected by the modification require no further action under the Machinery Directive.
3. Separate responsibilities: each manufacturer remains responsible for the conformity of the machinery placed on the market under its own CE marking, while the employer/user remains responsible for the safe operation of the assembly at the workplace under the applicable national provisions implementing Directive 2009/104/EC. This includes ensuring that installation and interfaces between machines do not compromise the safety of the overall installation.

A practical example is a container labelling line CE marked as an assembly of machinery in 2010. The line comprises a sleeve applicator and an electric shrink tunnel, each equipped with its own control panel but interconnected by interface signals.

Assume that, in 2020, the tunnel is replaced by a new model from a different manufacturer. The new tunnel must be placed on the market with its own CE marking, but the entire production line does not need to undergo a new conformity assessment. This is because the replacement does not create new risks for the production line or, where new hazards arise, these are adequately controlled by the protective measures already present on the installation.

If the risk assessment shows that the modification or integration introduces new hazards that are not adequately controlled by the existing protective measures, and significantly affects the performance, operating modes or overall safety of the installation, the intervention may constitute a substantial modification.

Let us again consider the example of the container labelling line comprising a sleeve applicator and an electric tunnel, but assume that the control system of the sleeve applicator directly controls both the operating functions and the safety functions of the tunnel.

In this case, replacement of the sleeve applicator alone may constitute a substantial modification of the entire assembly. This is because the applicator represents the logical control unit of the line: replacing it affects the control architecture, safety-related control circuits and interfaces with the other machinery, and may therefore introduce new hazards or alter the performance of existing safety functions.

With regard to such situations, the Guide to application of the Machinery Directive states:

[Guide to application of the Machinery Directive 2006/42/EC – Edition 2.3 of 2023] §39 Assemblies comprising new and existing machinery 

[…] If the replacement or the addition of new constituent units in an existing assembly of machinery has a substantial impact on the operation or the safety of the assembly as a whole or involves substantial modifications of the assembly, it may be considered that the modification amounts to the constitution of a new assembly of machinery to which the Machinery Directive must be applied. In that case, the whole assembly, including all its constituent units, must comply with the provisions of the Machinery Directive.

The modification is therefore equivalent to the constitution of a new assembly of machinery. Consequently, the person carrying out the modification must assume the responsibilities of the manufacturer and apply the Machinery Directive to the assembly as a whole.

The entire assembly must therefore undergo a new conformity assessment and be provided with a new Technical File, a new EC Declaration of Conformity and overall CE marking.