EN 15085
CL1 VS CL2
TBM
CL1 vs CL2 vs CL3: Which EN 15085 Certification Level Does Your TBM Need?
By First Welding Certification Technical Editorial Team
6 Min Read
31 Aug 2026
Table Of Contents
- CL1 vs CL2 vs CL3: What actually changes?
- EN 15085 certification levels compared
- How to assess a TBM or track-bound machine component
- A Practical CL1 / CL2 / CL3 Decision Process
- Why the Weld Itself Matters
- Where WPS, WPQR and ISO 9606 Fit Into the Picture
- Common Mistakes When Choosing the Certification Level
- When Should You Pursue EN 15085 Certification?
- Frequently Asked Questions
- Conclusion
- Take the Next Step with First Welding Certification Pvt Ltd
EN 15085 CLASSIFICATION AT A GLANCE
The safety relevance of the welded component determines the certification level.
CL1
Structural & safety relevance
CL2
Functional equipment
CL3
Auxiliary component
CL1 vs CL2 vs CL3: What Actually Changes?
The simplest way to understand the three levels is through safety relevance.
| Classification | Safety relevance | Practical meaning |
|---|---|---|
| CL1 | High | Failure of the welded component can have serious consequences for people and overall function |
| CL2 | Medium | Failure can impair overall function and/or potentially lead to personal injury |
| CL3 | Low | Failure is unlikely to directly impair the overall function or cause personal injury |
This classification doesn’t just show how good a welding company is.CL1 isn’t a better or more advanced type than CL2, and CL3 isn’t just a basic welding certificate.The classification is based on how important safety is for the welded railway vehicles or parts, and the welding and design needs connected to them.This becomes very important when a company makes many welded parts using the same type of machinery.
EN 15085 Certification Levels Compared
EN 15085 CL1 Certification: High Safety Relevance
CL1 is for welded parts of railway vehicles and components where safety is very important.
Examples of such parts include heavy welded structures or other welded parts that are important for safety.
The main thing to look at is not how big the part is, but what happens if it fails.
For example, think about a machine that runs on the railway track.
If this machine has a welded part that is important for how it works, and if that part fails, it could be dangerous for the machine or for people using it, then the part needs to be classified properly.That’s why EN 15085 CL1 certification should be done through a proper classification process, not just by picking the highest safety level.
EN 15085 CL2 Certification: Medium Safety Relevance
CL2 is for welded parts of railway components where safety is somewhat important.
This could be a welded part that, if it fails, might cause some equipment to stop working or create a safety issue.However, it’s not important enough to be in the CL1 category.The key point is that CL2 should not be used as a general replacement for CL1.
When determining the right classification and welding requirements, both should be considered together.
EN 15085 CL3 Certification: Low Safety Relevance
CL3 is for welded parts of railway components where safety is not very important.
This could be parts that are secondary or have a low impact if they fail, depending on their role and classification.
But you should never do this:
“This part is small, so it’s CL3.”
That’s not a good way to classify parts.
A small part can have a big safety role, and a big part can have a small safety role.
How Do You Assess a TBM or Track-Bound Machine Component?
This is when the “CL1 vs CL2 welding” article ends too early.
The assessment should start with the component, not the type of machine.
Think about a machine on rails that has:
– a welded main frame,
– equipment support,
– structural brackets,
– access platforms,
– safety guards,
– mounting parts,
– extra enclosures.
Do all these parts automatically fall under the same EN 15085 classification?
Not always.
The classification depends on the function and safety importance of each part.
Illustration A – Main Structural Frame
If a part fails and could affect the machine’s structure or safety, then its safety importance needs to be checked.
Illustration B – Equipment Support of Safety Importance
Support for equipment that is needed for safe operation may be more important than brackets holding non-critical parts.
Illustration C – Extra Enclosure
If an enclosure fails but isn’t needed for safe operation, its importance is less.
These examples are just for showing the idea.
The real classification should be based on the actual requirements.
A Practical CL1 / CL2 / CL3 Decision Process
Instead of asking, “Which certification should I choose?”
Use this step-by-step process.
1.Identify the Exact Product
Figure out exactly what you are making, fixing, repairing, or welding.
Do not start with:
“We manufacture TBMs.”
Start with:
“Which welded railway vehicle, track-bound machine, or railway part is being made?”
If you’re talking about a conventional civil-engineering Tunnel Boring Machine, don’t just assume that EN 15085 applies. EN 15085 is about welding for railway vehicles and parts, so you need to first make sure the product is actually used in railway applications and define the exact scope.
If your TBM refers to a Track-Bound Machine, clearly state that meaning in your technical documents and in your writing.
2.Break the Product Into Welded Components
Make a list of all the separate parts that are welded together.
For each part, note:
– what it does,
– its structural role,
– where the welds are,
– the material it’s made from,
– the welding process used,
– where it is located on the product,
– how it connects to other parts,
– what happens if it fails.
This gives a much better starting point than just writing “TBM” on a certification form.
3.Determine Safety Relevance
Ask the most important question in engineering: What happens if this welded part breaks? Think about whether it could:
– make the product unsafe to use,
– cause someone to get hurt,
– weaken the structure,
– stop something important from working,
– create a dangerous situation.
The bigger the risk, the more carefully you must understand how safe this part is.
4.Determine the Applicable Welding Requirements
The classification can’t be separated from the welding design needs. EN 15085 is a set of standards, not one single rule. It covers different areas like certification of the manufacturer, design, production, checking, testing, and keeping records.
This is where the classification becomes important.
5.Define What the Manufacturer Actually Does
The certification needs to match the real activities the company does. Depending on the company and what it does, the work can include areas like:
– designing parts,
– making products,
– maintaining or fixing equipment,
– buying parts,
– supplying goods,
– coordinating welding,
– checking and testing.
So, even if two companies work with similar railway parts, their certification needs might be different.
6.Confirm the Certification Level
Only after you’ve figured out the product, the parts, the safety risks, the welding needs, and the scope of the company’s work should you decide on the correct certification level—CL1, CL2, or CL3. This order helps avoid a common mistake:
Choosing a certification first and then trying to make your production fit into it.
Why the Weld Itself Matters
Classification of components cannot happen without considering their welded joints.
When thinking about EN 15085 certification in practice, it follows this order:
Component → Function → Safety → Weld Joint → Weld Joint Requirements → Production Controls
That’s why having just a certificate on the wall doesn’t mean you have EN 15085 certification.
The manufacturer must have a welding process that can create weld joints of the required quality, as approved by their certification.
Some of the important requirements include:
qualified welding staff,
welding procedures,
welding coordination,
inspection,
testing,
traceability,
controlled production records.
For more details on these requirements, see the EN 15085 certification requirements article on First Welding Certification Pvt Ltd.
Where WPS, WPQR and ISO 9606 Fit Into the Picture
Selecting CL1, CL2, or CL3 does not replace the need to control the welding process properly.
Once the correct scope is decided, the manufacturer must prove that the welding done within that scope is properly controlled.
WPS and WPQR
A Welding Procedure Specification (WPS) is a guide for doing welding in production.
A Welding Procedure Qualification Record (WPQR) is a document that shows the results of tests that prove a welding procedure can produce good results within its qualified range.
So, the connection is like this:
WPQR → Test Results
WPS → Instructions for doing welding in production
If you need to make a new or change an existing welding procedure, check the welding procedure qualification information from First Welding Certification Pvt Ltd to find the right path for qualification.
For more information on the relationship between WPS and WPQR, see our article about WPS vs WPQR.
ISO 9606 Welder Qualification
The welding process is just one part of controlling welding properly.
It is also important that the person doing the welding is properly qualified for that task.
This is where ISO 9606 welder qualification becomes important.
The difference is clear:
WPQR proves the welding procedure is suitable.
ISO 9606 proves the welder is qualified for the job.
At First Welding Certification Pvt Ltd, we offer ISO 9606 welder qualifications for welders who need to be certified.
This creates a full compliance chain:
Correct certification scope → Qualified procedure → Controlled WPS → Qualified welder → Welding done → Inspection and records
For a manufacturer, this is far more valuable than just knowing their certificate is CL1, CL2, or CL3.
Common Mistakes When Choosing the Certification Level
Mistake 1: Choosing CL1 Because It Sounds Safer
It’s not always better to pick a higher level just because it sounds more reliable.
The certification level should match the safety role and the component’s purpose.
Mistake 2: Choosing CL3 Because the Component Is Small
The size of a part doesn’t decide how important it is for safety.
A small weld can still have a major safety role.
Mistake 3: Assigning One Classification Level to the Entire Machine
A machine can have parts with different safety needs.
It’s better to start by checking each part individually.
Mistake 4: Confusing Certification Level with Welding QualityCL1, CL2, and CL3 are related to welding quality but are not the same thing.
All rules and requirements need to be considered.
Mistake 5: Misunderstanding CL4 Because of Old Material
EN 15085 often mentions CL4, but you should check the date and context.
The current system only includes CL1, CL2, and CL3.
Mistake 6: Thinking Certification Is Just a Paperwork
A certificate can’t fix a poor welding system that doesn’t match the actual production.
Your certified scope, personnel, procedures, controls, and inspections all need to match in real use.
When Should You Pursue EN 15085 Certification?
If your organization does any welding work on railway vehicles or parts that fall under the EN 15085 standard, you need to decide on the classification before you finalize your certification plan.
Here’s a step-by-step way to prepare:
1.Figure out what product you’re making
↓
2.Find out which parts are welded
↓
3.Check if the welding is important for safety
↓
4.Find out what welding rules apply
↓
5.Decide what welding jobs are needed and what they cover
↓
6.Look at the welding procedures and check the qualifications of the people doing the welding
↓
7.Choose the right certification level: CL1, CL2, or CL3
↓
8.Get ready for the assessment
If your organization is ready to start the EN 15085 certification process, check out our EN 15085 Certification for the right path for your business.
Frequently Asked Questions
What is EN 15085 CL1 certification?
EN 15085 CL1 is the classification level associated with welded railway vehicles and components having high safety relevance
What is the difference between EN 15085 CL1 and CL2?
CL1 is for high safety relevance of welded railway vehicles and components, and CL2 is for medium safety relevance. The applicable classification level should be established depending on the welded components and their applicable safety relevance and requirements rather than chosen arbitrarily by the manufacturer.
Is CL3 lower than CL2?
There is no universal answer based solely on the term “TBM.” First establish whether the machine falls within the relevant railway or track-bound application and then assess the safety relevance of its welded components.
A conventional civil tunnel boring machine should not automatically be classified under EN 15085.
Which EN 15085 certification level does my TBM need?
There is no universal answer to this question since you cannot just use the term “TBM” to define the applicable certification. Determine first if the equipment qualifies as railway equipment or track-bound equipment and then analyze the safety relevance of the applicable welded components. A conventional civil tunnel boring machine should not necessarily be considered for EN 15085.
Is WPS & WPQR required for EN 15085 certification?
Welding procedure is an integral part of controlled welding production but the specific procedure and its qualification requirements depend on the process and the specific product. If qualification of the applicable welding procedure is required, the procedure should be qualified. WPQR can provide such qualification.
Conclusion
Whether to choose EN 15085 CL1, CL2, or CL3 should not start with asking, “Which certification has the highest level?”
It should begin by looking at the welded part:
Product → Component → Function → Safety Importance → Welding Requirements → Welding Range → Certification Level
This approach helps manufacturers consider the right certification based on their production process, not just on how complicated or big the machine is.
For railway and track-mounted products, the correct certification level also has to match the right welding technique, trained workers, production checks, and inspections.
Looking at all these things before starting the certification process helps avoid problems with scope, extra qualifications, and the need for redoing work.
Take the Next Step with First Welding Certification Pvt Ltd
If you are checking the certification level for EN 15085 in your company, looking into your welding scope, or assessing the requirements for CL1, CL2, and CL3, First Welding Certification Pvt Ltd can help you move forward.
We start with EN 15085 certification, include WPS, WPQR, and ISO 9606 welder qualifications; everything is focused on building the correct framework for welding qualification and certification.
First Welding Certification Pvt Ltd – Building trust through welding and certification.