What is PD 5500:2024+A2:2025 - Specification for unfired pressure vessels about?

PD 5500:2024+A2:2025 is the UK’s national code for unfired pressure vessels. It provides comprehensive technical and procedural requirements for the design, manufacture, inspection, testing, and verification of new unfired pressure vessels.

The code applies to vessels constructed from various materials, primarily carbon steels, ferritic alloy steels, and austenitic steels, and it includes supplements for vessels made of aluminium, copper, nickel, titanium, and duplex materials.

Amendment 2 (A2:2025) is the second scheduled update to the 2024 edition, bringing essential technical refinements, editorial improvements, and significant additions like guidance for additive manufacturing methods.

Who is PD 5500:2024+A2:2025 - Specification for unfired pressure vessels for?

PD 5500:2024+A2:2025 should be used by:

Mechanical engineers involved in the design and specification of pressure vessels.
Pressure vessel designers creating compliant and efficient vessel structures.
Pressure vessel manufacturers producing vessels for domestic and international markets.
Inspection and testing bodies verifying vessels against safety and compliance requirements.
Organizations across multiple sectors, including: oil and gas, petrochemical, process plant, energy generation (including nuclear) and food and drink.
Companies engaged in the UK’s nuclear new build programme, needing certified vessels for new sites.
Global users in Commonwealth/former Commonwealth countries, Middle East and Asia (e.g., China, Malaysia).
New users migrating from other standards, such as BS EN 13445 or ASME, seeking a UK-aligned alternative.
Past purchasers of previous PD 5500 editions (2015, 2018, 2021) needing to stay current with the latest requirements.

What does PD 5500:2024+A2:2025 - Specification for unfired pressure vessels cover?

The scope of PD 5500:2024+A2:2025 includes:

Requirements for the design, fabrication, inspection, and testing of unfired pressure vessels.
Guidance on compliance verification and legislative alignment (e.g., PE(S)R).
Material specifications including steels, aluminium, copper, nickel, titanium, duplex, and now additive manufacturing materials.
Technical procedures for nozzle design, floating head exchanger drawings, and reinforcement in complex geometries (e.g., knuckle regions).
A library of Enquiry Cases allowing for the inclusion of new technologies or exceptions not yet fully covered in core text.

Amendment 2 adds:

Updates to material tables and figures.
A new Enquiry Case (EC 145) on additive manufacturing using DED Arc techniques.
A new Enquiry Case (EC 147) on nozzle reinforcement in the knuckle region of dished ends.

Why should you use PD 5500:2024+A2:2025 - Specification for unfired pressure vessels?

Organizations and professionals engaged in the design, manufacture, and inspection of pressure vessels should adopt PD 5500:2024+A2:2025 for the following key reasons:

Regulatory alignment: The standard is fully aligned with the UK’s Pressure Equipment (Safety) Regulations (PE(S)R), supporting compliance with legal and safety obligations and enabling both UKCA and CE marking where applicable.
Support for innovation: The inclusion of a new Enquiry Case on additive manufacturing (EC 145) provides the industry with a practical framework to adopt advanced manufacturing techniques such as wire-based DED Arc, while maintaining full compliance with essential safety requirements.
Clarity and usability enhancements: Amendment 2 delivers editorial improvements, figure corrections, and clarifications that enhance the accuracy, readability, and user experience of the document, helping users to apply the code more efficiently and with greater confidence.
Technical updates based on industry feedback: All updates are developed through consultation with national pressure vessel experts and user contributions, ensuring that the standard reflects the latest technological developments and real-world challenges.
Comprehensive and authoritative coverage: PD 5500 consolidates all critical information in one authoritative source, including material specifications, design methodology, fabrication techniques, inspection protocols, and compliance verification – making it a complete solution for pressure vessel code requirements.
Strategic relevance for key sectors: The standard is widely used in critical industries such as oil and gas, petrochemical, energy (including nuclear), process plant, and food and beverage, making it a highly relevant and trusted document for safety-critical applications.
Global recognition and applicability: While primarily a UK code, PD 5500 is also recognized and used internationally, particularly in Commonwealth nations, the Middle East and parts of Asia, supporting global project specifications and cross-border compliance.

What's changed?

PD 5500:2024+A2:2025 introduces a range of technical updates, editorial refinements, and new content designed to improve the clarity, usability, and technical robustness of the standard. These changes reflect feedback from users, expert committee input, and evolving industry needs.

Revised, expanded, and corrected entries for BS EN materials in Table 2.1-2.
Inclusion of duplex materials for castings and fittings in Tables Du.2.1-2 and Du.2.1-3.
Addition of nickel alloy materials for forgings, castings, and fittings in Table Ni.2.3-6.
Updated modulus of elasticity values in Table Ni.3.6-3 to ensure alignment with current data.
Updates to the procedure for nozzle reinforcement, enhancing the accuracy and reliability of nozzle design.
Clarification of effective lengths within Section 3.6.2.3.2.1, Table 3.6-2, and Figure 3.6-1, improving interpretability for structural calculations.
Corrections to drawings of floating head exchangers in Figures 3.9-1 and 3.9-9.
Correction of footnote f in Table 4.5-1, providing clearer technical guidance.
Introduction of new enquiry cases: EC 145 Additive manufacture using wire-based DED arc techniques and EC 147 Nozzle reinforcement in the knuckle region of dished ends.
Ongoing refinement of internal text clarity and consistency.
Updates to internal and external normative references to reflect the most current industry standards and regulatory documents.

By engaging with the latest revision, organizations demonstrate a commitment to safety, compliance, technical excellence, and continuous improvement in pressure vessel design and manufacture.

PD 5500:2024+A2:2025 PDF

Specification for Unfired Pressure Vessels

Current

Published:

30 Sep 2025