When fasteners are ordered without explicit documentation requirements, there is no guarantee that what is delivered is what was specified. Bolts marked with strength class 10.9 may be manufactured from material that does not meet the requirements of ISO 898-1 for that class. Visual inspection does not reveal this. In oil and gas, offshore and energy infrastructure, the consequences of a failed bolted joint in a pressurised system are serious. Traceability and technical approval of fasteners are not additional administrative requirements. They are fundamental preconditions for safe operation.
Certificate types under EN 10204: what is required when?
|
Certificate type |
Who certifies |
Batch-specific |
Recommended for |
|
2.1 Declaration of compliance |
Manufacturer |
No |
Not sufficient for critical applications |
|
2.2 Test report |
Manufacturer |
No |
Not sufficient for critical applications |
|
3.1 Inspection certificate |
The manufacturer's own inspection body |
Yes |
Minimum requirement: critical industrial applications |
|
3.2 Inspection certificate |
Independent third party |
Yes |
Critical offshore and DNV GL applications |
What is the industrial problem?
Traceability of fasteners means that every batch of bolts, nuts and washers can be linked to a documented production history covering raw material, heat treatment, mechanical testing and surface treatment. Without this link it is not possible to verify that the delivered material actually meets the mechanical properties the specification requires.
Counterfeit and incorrectly marked fasteners are a reality in global supply chains, including in the European market. A bolt that looks correctly marked, but is manufactured from material with lower tensile strength than stated, is installed and tightened to the specified torque without the fault being detected. The failure occurs under operational load, often long after installation.
Marking requirements under ISO 898-1 and ISO 3506
ISO 898-1 requires that bolts in strength class 8.8 and above are marked with the strength class number and manufacturer identification directly on the head. Nuts in class 8 and above are marked correspondingly. This is not a recommendation. It is a requirement of the standard. A bolt without such marking is by definition not in conformity with ISO 898-1, regardless of what the supplier states in the quotation.
In NORSOK-regulated installations and DNV GL-classified systems, unmarked bolts in critical strength classes are not acceptable. For stainless and acid-resistant steel under ISO 3506, the material codes A2-70, A4-70 and A4-80 are examples of a combined material and strength class designation. The same marking principle applies: material code and manufacturer identification must be present directly on the component.
Which standards and compliance requirements apply?
EN 15048 defines requirements for non-preloaded structural bolted joints, including marking and certification. EN 14399 regulates preloaded structural bolts. For imperial fasteners, ASTM standards apply with an accompanying material certificate. NORSOK M-650 sets requirements for supplier certification for fasteners used in offshore and petroleum installations on the Norwegian continental shelf.
In all cases the purchase order must refer explicitly to the applicable standard. «M20 bolt» is not a valid technical specification in an audit context. Standard, strength class, surface treatment and certificate type must be stated on every order line.
Why does standard locking fail without traceability?
A lack of traceability does not only affect compliance risk: it affects the actual mechanical performance. A fastener without a verified strength class may have a lower preload capacity than specified. When the initial preload is insufficient, preload loss under vibration and dynamic load is accelerated. Standard locking methods such as spring washers and nylon lock nuts depend on sufficient initial friction force to maintain clamping force: and the friction force is proportional to the preload.
The consequences are not visible at installation. The joint appears tight. The fault appears under operational load, typically in the form of progressive leakage, loose bolts or structural movement. Identifying the source of such events afterwards, without traceable documentation, is resource-intensive and often impossible.
Why are NORD-LOCK washers necessary?
NORD-LOCK wedge-locking washers provide an additional level of safety that is independent of friction variation. The wedge-locking principle maintains clamping force mechanically through geometric tension locking: not through friction alone. In situations where the traceability of the underlying fasteners is not fully verified, NORD-LOCK provides a documented contribution to the integrity of the joint.
For offshore installations, rotating machinery and pressurised process flanges, the combination of traceable fasteners with a verified strength class and NORD-LOCK wedge washers is the specification that minimises the risk of preload loss during operation. INDUSTRISALG carries NORD-LOCK wedge washers in all common dimensions in stock.
Requirements for the supplier: minimum list
A qualified supplier of fasteners for industrial use must as a minimum be able to offer:
- ISO certification to ISO 9001:2015: confirms that the quality system has been independently audited
- EN 10204 type 3.1 material certificate per batch with lot number and production date
- Manufacturer identification and lot number on the delivery, traceable to the certificate
- Declaration of conformity against the stated standard on the order confirmation
Conclusion
Marking and traceability of fasteners are not additional administrative requirements. They are the preconditions for purchased components actually meeting the specification they were ordered against. ISO certification of the supplier confirms that the quality system is in place. A type 3.1 certificate per batch confirms that the delivered material has been tested and documented. These requirements must be applied consistently, including on urgent orders.
RELATED READING
- Standardised range: why fewer variants reduce total costs
- DIN vs ISO in practice: when “the same M10/M12” means different wrench sizes
Get in touch
Send us the purchase order or the specification — and we will confirm that the documentation requirements are covered and that the correct certificate type accompanies the delivery. INDUSTRISALG is ISO 9001:2015 certified and supplies a 3.1 material certificate on everything purchased after 2020 as standard. We also deliver on urgent orders with full traceability.