April 2026: New European Standard for Metal Bellows Expansion Joints Enhances Fluid System Safety

The European Committee for Standardization (CEN) has released an important update in the field of fluid systems and components for general use, publishing one major new standard in April 2026. EN 14917:2021+A1:2026, the latest revision for metal bellows expansion joints in pressure applications, introduces robust requirements for the design, manufacture, and installation of these critical components. The changes reflect significant advances in technical precision, lifecycle safety, and EU regulatory alignment—ensuring safer and more reliable operation of industrial fluid systems across Europe and internationally.

Overview / Introduction

Fluid systems are the veins of modern industry—transporting liquids and gases safely under pressure in fields ranging from oil and gas to chemical processing, power generation, and water treatment. At the heart of many pressurized piping systems are metal bellows expansion joints. These specialized components are critical for absorbing movement, compensating for thermal expansion, and preventing damage from vibration or pressure fluctuations.

International standards in this sector, such as EN 14917:2021+A1:2026, set out the technical and safety framework that underpins the design, manufacturing, testing, and installation of these components. Through standardized practices, businesses benefit from improved safety, performance reliability, and global market access. This article provides industry professionals, engineers, and compliance managers an in-depth look at the new European Standard and what it means for their operations.

Detailed Standards Coverage

EN 14917:2021+A1:2026 – Metal Bellows Expansion Joints for Pressure Applications

Metal bellows expansion joints for pressure applications

EN 14917:2021+A1:2026 specifies comprehensive requirements for the design, manufacture, and installation of metal bellows expansion joints with a circular cross-section, intended for pressure applications with a maximum allowable pressure above 0.5 bar. This standard applies to all sectors where pressurized piping or vessels are used—most notably in energy, petrochemical, power generation, water infrastructure, and pharmaceutical industries.

Scope and Applicability

• Design Requirements: The standard covers extensive design criteria for all types of metal bellows expansion joints—axial, angular, lateral, and universal—ensuring safe performance under specified operating pressures and temperatures.
• Material Specifications: EN 14917 details stringent requirements for materials used in pressure-bearing components, attachments, and hardware, including required ductility, corrosion resistance, impact energy values, and traceability documentation.
• Manufacturing & Quality: The standard defines processes for welding, forming, and heat treatment; joint design; tolerances; and permanent joint quality. Forming processes and allowable materials are tightly specified to prevent surface/internal defects and ensure long-term integrity under dynamic or static pressure loads.
• Classification: Expansion joints are classified by the type of movement absorbed and their level of pressure thrust restraint, aligning design requirements with application-specific risks.

Key Requirements and Specifications

• Stress Calculations: New or revised methods for calculating allowable stresses below and within the creep range, taking into account design lifetime, pressure, and temperature effects, including harmonized fatigue calculation for different bellows materials.
• Material Documentation: All materials must comply with relevant European material standards or approved equivalents, with full traceability and inspection documentation per EN 764-5:2014.
• Testing and Inspection: Mandates a rigorous testing regime including non-destructive testing (NDT) of welds, in-process inspections, final assessment, and fully documented reporting packages.
• Installation Guidelines: Detailed requirements for correct handling, packaging, storage, and installation, as improper installation is a key source of failure in service.
• Marking and Labelling: Clear marking of products per specified parameters, supporting maintenance and traceability throughout the component's lifecycle.

What’s New in the 2026 Edition?

Key changes from previous versions include:

• Full alignment with EU Pressure Equipment Directive 2014/68/EU (PED), including comprehensive risk assessment requirements
• Complete revision and restructuring of design clauses, with updated stress and fatigue calculation methods and new design rules for creep range conditions
• Harmonization and extension of fatigue calculation techniques (now featuring four fatigue curves for different material classes)
• Expansion of material categories and their temperature properties, with updated and consolidated annexes covering calculation benchmarks and risk analyses
• Revised requirements for manufacturing, testing, documentation, and hardware stress calculation

Key highlights:

• Incorporates Amendment 1 (2026), fully superseding EN 14917:2021
• Applies to all bellows expansion joints in pressure service above 0.5 bar
• Sets rigorous documentation and testing requirements for traceability and compliance

Access the full standard:View EN 14917:2021+A1:2026 on iTeh Standards

Industry Impact & Compliance

How Does EN 14917:2021+A1:2026 Affect Businesses?

For manufacturers, operators, and specifiers in sectors that rely on robust piping and pressure vessels, compliance with the new EN 14917 standard is non-negotiable:

• Market Access: Adherence to harmonized European standards is often mandatory for selling products within the EU and, in many cases, globally.
• Legal Compliance: This standard underpins conformity with the EU Pressure Equipment Directive, essential for CE marking and legal operation within member states.
• Operational Safety: Implementing the updated requirements reduces the risk of catastrophic failure, enhancing workplace safety and environmental protection.

Compliance Considerations & Timelines

• Transition Period: Organizations must implement the standard by October 2026, after which conflicting national standards must be withdrawn.
• Process Updates: Companies should review and revise their design calculations, materials sourcing, quality assurance, and documentation processes to align with the new requirements.
• Certification & Audit: All stages—from design through manufacture and installation—may be subject to external audit, especially for CE marking and third-party certification.

Benefits of Adoption

• Increased reliability and reduced maintenance costs
• Enhanced international acceptance and simplified cross-border supply chains
• Demonstrated due diligence in risk management and legal compliance

Risks of Non-Compliance

• Product recalls, fines, or blocked market access
• Increased risk of in-service failures, unplanned shutdowns, and litigation
• Damaged organizational reputation and customer trust

Technical Insights

Common Technical Requirements and Best Practices

• Material Selection: Only materials tested and certified as per relevant EN material standards are permitted, with clear requirements for low- and high-temperature performance.
• Welding & Forming: All welders and forming personnel must be qualified and processes validated, with specific rules for circumferential and longitudinal welds.
• Design Calculations: Employ up-to-date calculation methods for pressure resistance, creep, fatigue, and column instability. Design validation must cover worst-case pressure and temperature scenarios.
• Testing & Certification:
  • Non-destructive testing (NDT) of all pressure-retaining welds
  • Material and product documentation in accordance with EN 764-5:2014
  • Proof testing and, where required, additional assessments for long-term creep or fatigue performance
• Traceability & Documentation: Each expansion joint must be fully traceable to its material and manufacturing data, including test results, certifications, and installation instructions.

Implementation Best Practices

1. Early Gap Analysis: Review existing procedures and designs against the new standard to identify areas needing change.
2. Supplier Engagement: Ensure all material and component suppliers understand and comply with new requirements (particularly around material properties, traceability, and documentation).
3. Staff Training: Provide updated training to engineering, QA/QC, and installation teams for the revised standard.
4. Documentation Systems: Upgrade data management to handle expanded documentation and traceability needs.

Testing and Certification Considerations

• Non-destructive testing must be performed by qualified personnel (EN ISO 9712 compliant)
• Strict quality levels for welds and forming processes (EN ISO 5817)
• Full documentation packages, including certificates of conformity, must be retained through the product lifecycle

Conclusion / Next Steps

The new EN 14917:2021+A1:2026 is a milestone standard for fluid system safety and reliability, reflecting the latest technical and regulatory thinking for metal bellows expansion joints. For professionals charged with ensuring the integrity of pressurized systems, understanding and implementing this standard is critical.

Key Takeaways:

• The 2026 revision introduces updated design, testing, documentation, and legal alignment requirements
• Compliance is required for continued market access and risk management
• Early adoption ensures operational continuity, safety, and customer trust

Recommendations:

• Immediately review and integrate EN 14917:2021+A1:2026 into your organization’s product design, supply chain, and quality control processes
• Train technical and compliance teams on the standard’s new provisions
• Consult with certification bodies where appropriate to ensure conformity

Explore the complete standard and stay informed on industry requirements:View EN 14917:2021+A1:2026 on iTeh Standards

Stay up to date with essential standard changes and ensure your business remains at the forefront of safety, compliance, and technical best practice in modern fluid systems.