When purchasing steel, stainless steel, nickel alloys, forgings, flanges, pipes, or other critical metallic products, buyers often request an EN 10204 material certificate.
Two of the most commonly specified certificate types are:
EN 10204 3.1 and EN 10204 3.2.
Both provide specific inspection results for the supplied material, but there is an important difference:
A 3.1 certificate is validated by the manufacturer’s authorized inspection representative, while a 3.2 certificate involves additional validation by an independent inspection representative or the purchaser’s authorized representative.
Understanding this distinction is important when sourcing materials for pressure equipment, oil and gas projects, chemical processing, power generation, offshore applications, and other regulated industries.
Quick Comparison: EN 10204 3.1 vs 3.2
| Requirement | EN 10204 3.1 | EN 10204 3.2 |
| Specific inspection results | Yes | Yes |
| Material traceability | Yes | Yes |
| Chemical composition | Typically included | Typically included |
| Mechanical test results | Typically included | Typically included |
| Manufacturer validation | Yes | Yes |
| Independent validation | No independent purchaser/TPI validation required by 3.1 | Yes |
| Third-party involvement | Normally not required | Often required |
| Typical cost | Lower | Higher |
| Inspection coordination | Relatively simple | More complex |
| Typical application | Standard industrial and pressure equipment procurement | Critical or project-specific applications requiring independent validation |
The fundamental difference is therefore not simply the amount of test data on the certificate.
The key difference is who validates the inspection results and confirms compliance.
C22 vs C276 in Different Environments
| Service Environment | C22 | C276 | General Consideration |
| Oxidizing acids | Excellent | Very Good–Excellent | C22 often favored |
| Reducing acids | Excellent | Excellent | C276 has strong service history |
| Hydrochloric acid | Excellent | Excellent | Conditions determine selection |
| Sulfuric acid | Excellent | Excellent | Concentration and temperature critical |
| Chloride solutions | Excellent | Excellent | Both strong candidates |
| Mixed oxidizing/reducing media | Excellent | Excellent | C22 often attractive |
| Pitting environments | Excellent | Excellent | Verify actual conditions |
| Crevice corrosion | Excellent | Excellent | Both strong candidates |
| Chloride SCC | Excellent | Excellent | Both significantly outperform common stainless steels |
This table should be treated as a general engineering comparison rather than a corrosion-rate specification.
For critical applications, corrosion data for the exact chemical concentration and temperature should always be reviewed.
What Is EN 10204?
EN 10204 is a European standard defining different types of inspection documents supplied with metallic products.
These documents provide evidence that supplied materials comply with the requirements specified in the purchase order and applicable material specification.
EN 10204 inspection documents are commonly encountered when purchasing:
- Plates
- Sheets
- Bars
- Pipes
- Tubes
- Forgings
- Flanges
- Fittings
- Fasteners
- Rings
- Custom-machined metallic components
Depending on the certificate type, the document may contain material identification, chemical composition, mechanical properties, test results, heat numbers, and other traceability information.
What Is an EN 10204 3.1 Certificate?
An EN 10204 Type 3.1 Inspection Certificate confirms that the supplied products comply with the requirements of the purchase order and provides the results of specific inspection.
The certificate is validated by the manufacturer’s authorized inspection representative who is independent of the manufacturing department.
A typical 3.1 certificate may include:
- Manufacturer name
- Customer or purchase order reference
- Material grade
- Product specification
- Dimensions
- Quantity
- Heat number
- Chemical composition
- Tensile properties
- Yield strength
- Elongation
- Hardness, where applicable
- Impact testing, where required
- Heat treatment condition
- Applicable supplementary tests
- Inspection results
- Authorized validation
The exact contents depend on the applicable material standard and purchase-order requirements.
What Does "Specific Inspection" Mean?
This is an important concept in EN 10204.
Specific inspection means that testing and inspection results are associated with the products being supplied according to the applicable product specification and inspection requirements.
For example, a stainless steel plate supplied to an ASTM or EN material specification may have test results linked to its heat or test unit.
The certificate therefore provides actual inspection results associated with the supplied material rather than simply stating that the manufacturer’s general production process complies with a standard.
What Is an EN 10204 3.2 Certificate?
An EN 10204 Type 3.2 Inspection Certificate also confirms compliance with the purchase order and contains results from specific inspection.
However, it adds another level of independent validation.
The document is prepared with validation involving:
the manufacturer’s authorized inspection representative
and
either the purchaser’s authorized inspection representative or an inspector designated under applicable regulations.
In practice, independent inspection organizations may be engaged where required by the purchase order or applicable regulatory framework.
Organizations commonly encountered in industrial inspection projects include companies such as TÜV, Lloyd’s Register, DNV, Bureau Veritas, SGS, and others, depending on project requirements.
The Main Difference: Who Validates the Certificate?
This is the simplest way to understand EN 10204 3.1 vs 3.2.
EN 10204 3.1
The manufacturer performs the required inspections and tests.
The inspection certificate is validated by the manufacturer’s authorized inspection representative who is independent of the manufacturing department.
EN 10204 3.2
The manufacturer’s inspection representative is still involved, but additional validation is provided by an authorized independent inspection party or purchaser representative as required.
Therefore:
3.1 = manufacturer-controlled specific inspection
3.2 = specific inspection with additional independent validation
This additional involvement is why a 3.2 inspection route normally requires more planning, coordination, documentation, time, and cost.
Does 3.2 Mean the Material Is Better Than 3.1?
No.
This is one of the most common misunderstandings.
A material supplied with a 3.2 certificate is not automatically a higher-quality material than the same grade supplied with a 3.1 certificate.
For example:
ASTM A182 F51 flange with EN 10204 3.1
and
ASTM A182 F51 flange with EN 10204 3.2
may be manufactured to exactly the same material specification.
The difference is primarily the inspection and validation route, not necessarily the material grade itself.
A 3.2 certificate provides an additional level of independent verification.
What Does a Third-Party Inspector Check for 3.2?
The exact inspection scope depends on the purchase order, Inspection and Test Plan (ITP), material specification, and project requirements.
A third-party inspector may review or witness activities such as:
Material Identification
Verification of:
- Material grade
- Heat number
- Product markings
- Dimensions
- Quantity
- Traceability
Documentation Review
Review of documents such as:
- Mill certificates
- Purchase specifications
- Heat treatment records
- Test reports
- Manufacturing records
- Inspection procedures
Mechanical Testing
Where required, the inspector may witness or review:
- Tensile testing
- Impact testing
- Hardness testing
Chemical Verification
Depending on the project, this may include:
- Chemical analysis review
- Positive Material Identification (PMI)
Nondestructive Testing
Where specified:
- Ultrasonic Testing (UT)
- Liquid Penetrant Testing (PT)
- Magnetic Particle Testing (MT)
- Radiographic Testing (RT)
The actual scope must be agreed before production or inspection begins.
EN 10204 3.1 vs 3.2 and Third-Party Inspection
It is important not to assume that simply arranging a final third-party inspection automatically converts a 3.1 certificate into a 3.2 certificate.
A conventional pre-shipment inspection may verify:
- Dimensions
- Quantity
- Visual condition
- Markings
- Packing
- Documentation
That is not necessarily the same as the inspection and validation required for an EN 10204 Type 3.2 document.
If 3.2 certification is required, the inspection route should therefore be established before production and testing, with the responsible inspection parties clearly identified.
When Is EN 10204 3.1 Commonly Used?
EN 10204 3.1 certificates are widely used throughout industrial material procurement.
Typical applications include:
- Process piping
- Pressure vessel materials
- Heat exchangers
- Chemical processing equipment
- Oil and gas equipment
- Power generation
- Petrochemical plants
- Industrial machinery
- Structural components
For many projects, a properly issued 3.1 certificate provides sufficient material traceability and test documentation.
When Is EN 10204 3.2 Required?
A 3.2 certificate may be specified when the project requires an additional level of independent inspection.
Examples can include:
- Critical pressure-containing components
- Nuclear projects
- Offshore projects
- High-risk process equipment
- Critical forgings
- Certain EPC project specifications
- Purchaser-specific inspection requirements
- Applications requiring independent material verification
However, 3.2 should not be assumed to be mandatory simply because a component is used in a pressure system.
The applicable design code, regulatory requirements, material specification, purchaser specification, and conformity-assessment route should be reviewed.
EN 10204 3.1, 3.2 and PED
EN 10204 certificates are frequently encountered in projects involving the European Pressure Equipment Directive (PED) 2014/68/EU.
However, EN 10204 and PED should not be treated as the same thing.
EN 10204 defines inspection-document types.
PED establishes regulatory requirements for pressure equipment placed on the European market.
Depending on the pressure equipment category, material, manufacturer approval route, and conformity-assessment requirements, different documentation and inspection arrangements may apply.
For example, TÜV Rheinland describes routes involving manufacturer quality systems and 3.1 certificates as well as direct external inspection routes involving 3.2 certificates for metallic materials used in pressure equipment.
Therefore, the required certification route should always be determined from the actual project and regulatory requirements rather than simply requesting “PED + 3.2” by default.
Can a 3.1 Certificate Be Upgraded to 3.2 Later?
This can be difficult and should not be assumed.
If material has already been manufactured, tested, cut, machined, or shipped under a 3.1 inspection route, some of the activities that an independent inspector would normally need to witness or verify may no longer be available.
Additional testing, document review, traceability verification, or reinspection may be required.
In some cases, conversion may not be practical or acceptable.
Therefore, if the end user requires EN 10204 3.2, this requirement should ideally be stated at the RFQ and purchase-order stage.
Cost and Lead-Time Differences
EN 10204 3.2 certification normally costs more than 3.1 certification.
Additional costs may include:
- Third-party inspector fees
- Travel expenses
- Witness testing
- Additional laboratory testing
- Documentation review
- Inspection coordination
- Hold-point delays
Lead time can also increase because production and testing may need to be coordinated around inspector availability.
For international projects, this should be considered during quotation rather than after production has started.
What Buyers Should Specify in an RFQ
Instead of simply writing:
“MTC required”
buyers should clearly define the required documentation.
For example:
Material Certificate: EN 10204 Type 3.1
or:
Inspection Certificate: EN 10204 Type 3.2, with third-party inspection by an approved inspection organization.
For critical projects, the RFQ should also specify:
- Applicable material standard
- Required tests
- NDT requirements
- PMI requirements
- Inspection agency
- Inspection and Test Plan
- Witness points
- Hold points
- Documentation requirements
- Final dossier requirements
Clear requirements at the RFQ stage can prevent significant cost and schedule problems later.
Common Mistakes When Ordering 3.1 or 3.2 Certificates
Mistake 1: Assuming 3.2 Means Better Material
3.2 provides additional independent validation. It does not automatically change the material grade or manufacturing specification.
Mistake 2: Requesting 3.2 After Production
Independent inspection requirements should preferably be established before manufacturing and testing begin.
Mistake 3: Treating Any TPI Report as a 3.2 Certificate
A general third-party inspection report is not automatically equivalent to an EN 10204 3.2 inspection certificate.
Mistake 4: Checking the Certificate but Not Traceability
A certificate has limited value if the heat number on the material cannot be reliably traced back to the certificate.
Mistake 5: Ignoring the Purchase Order
The certificate should confirm compliance with the requirements specified in the purchase order and applicable material specification.
Conclusion
EN 10204 3.1 and 3.2 certificates both provide documented results from specific inspection, but the difference lies primarily in who validates the inspection and certification process.
EN 10204 3.1 relies on the manufacturer’s authorized inspection representative independent of the manufacturing department.
EN 10204 3.2 adds independent validation through the purchaser’s authorized representative or an inspector designated according to the applicable requirements.
For most industrial procurement, 3.1 certification is widely used. When additional independent verification is required by the purchaser, project specification, or regulatory route, 3.2 may be specified.
For critical orders, certification requirements should be established at the RFQ stage—not after manufacturing has begun.
MillsForge coordinates material traceability, EN 10204 certification, PMI, NDT, mechanical testing, dimensional inspection, and third-party inspection for alloy and industrial components according to project requirements.
FAQ
Both contain results from specific inspection. A 3.1 certificate is validated by the manufacturer's authorized inspection representative, while 3.2 involves additional validation by an authorized independent inspection representative or purchaser representative.
Not necessarily in terms of material quality. A 3.2 certificate provides a higher level of independent verification of compliance and inspection results.
No. TÜV is one possible inspection organization. The acceptable inspection party depends on the applicable regulations, purchaser requirements, and project specification.
An inspection organization may participate in a 3.2 inspection route if it satisfies the applicable contractual and regulatory requirements. The purchaser should confirm the approved inspection organization before placing the order.
The term MTC (Material Test Certificate or Mill Test Certificate) is commonly used in industry, but it does not by itself define the inspection-document type. The purchase order should explicitly state EN 10204 Type 3.1 when that certificate type is required
Not automatically. The inspection and testing scope depends on the material specification, purchase order, inspection plan, and requirements of the responsible inspection representatives.
