What is BS EN 13445-3:2021+A1:2025 - Unfired pressure vessels design about?

BS EN 13445-3:2021+A1:2025 is a part of the BS EN 13445 series, one of the world’s leading documents for pressure vessel design, manufacture, and inspection.

The European pressure vessels standards, specify requirements for the design, manufacture, inspection and testing of unfired pressure vessels.

Part 3 of the series covers design, a significant and important areas within the series. This part of the series provides the design rules for enabling safe, cost-effective pressure vessels to be designed, built, and inspected.

Other parts of the series:

BS EN 13445 Part 2: Materials
BS EN 13445 Part 4: Fabrication
BS EN 13445 Part 5: Inspection and testing
BS EN 13445 Part 6: Requirements for the design and fabrication of pressure vessels and pressure parts constructed from spheroidal graphite cast iron
BS EN 13445 Part 8: Additional requirements for pressure vessels of aluminium and aluminium alloys
BS EN 13445 Part 10: Additional requirements for pressure vessels of nickel and nickel alloys
BS EN 13445 Part 11: Additional requirements for pressure vessels of titanium and titanium alloys

The BS EN 13445 series is invaluable when demonstrating compliance with the European Pressure Equipment Directive (the PED).

Who is BS EN 13445-3:2021+A1:2025 - Unfired pressure vessels design for?

The BS EN 13445 series is used across manufacturing and engineering sectors. BS EN 13445-3:2021+A1:2025 is intended for:

Mechanical engineers.
Pressure vessel designers.
Pressure vessel manufacturers.
Pressure vessel inspectors.
Pressure vessels design consultancies.
Pressure vessels manufacturing companies.
Pressure vessels inspection bodies (used as part of the design of vessels for the European market).

All within in oil and gas, petrochemical, process plant, energy generation (including nuclear), and the food and drink industries.

What does BS EN 13445-3:2021+A1:2025 - Unfired pressure vessels design cover?

BS EN 13445-3:2021+A1:2025 provides:

Comprehensive set of design requirements, techniques, and guidance for pressure vessels.
Detailed requirements and information for design, manufacture, and inspection of pressure vessels.
Provides the necessary design requirements, techniques, and information to produce and maintain safe, cost-effective pressure vessels – all in accordance with relevant legislation and regulations.

Why should you use BS EN 13445-3:2021+A1:2025 - Unfired pressure vessels design?

BS EN 13445-3:2021+A1:2025 is used by organizations who commission, design, manufacture, inspect and maintain pressure vessels.

Used by:

Mechanical engineers,
Pressure vessels designers,
Pressure vessels manufacturers, and
Pressure vessels inspectors.
Industries & Sectors:
Oil and gas,
Petrochemical,
Process plant,
Energy generation (including nuclear), and
Food and drink.

What’s changed?

This first amendment to the 2021 edition of EN 13445-3 introduces the following technical and editorial changes. Including:

Revisions to subclauses 5.7.4.3.1 and 5.7.4.3.2.
Revisions to subclause 7.6.5.
Revisions to Clause 9 “Openings in shells”.
Revision to subclause 11.4.4.
Revisions to Clause 16 “Additional non-pressure loads”, including corrections to Figures 16.4-7 and 16.4-8, revisions to subclauses 16.6.2, 16.6.8 and 16.7.5, the addition of rules for the design of support brackets in 16.10, revisions to 16.12.5, and rules for the assessment of global loads on conical shells and conical transitions without knuckles in 16.15.
Revisions to Clause 18 “Detailed assessment of fatigue life”.
Revisions to Annex A “Design requirements for pressure bearing welds”.
The addition of new normative Annexes NA “Methods of determination of the structural hot‐spot stress by finite element analysis using shell or solid elements”, NB “Cycle counting and determination of equivalent stress range”, NC “Fatigue assessment of partial penetration welds” and ND “Methods for calculation of stress concentrations σtotal and stress concentration factors Kt”.

NOTE: The changes referred to include the significant technical changes but is not an exhaustive list of all modifications.

Editorial corrections:

Formula for austenitic steels as per 6.4 corrected in Table 6-1.
Formula reference corrected in Table P-3, Detail No. 3.4.
Formula and subclause references corrected in Annex Q.

Discover the other parts of the series below:

BS EN 13445-3:2021+A1:2025

Unfired pressure vessels - Part 3: Design

Current

Published:

30 Nov 2025