DIN EN 13445-3:2026-12

Safe design and calculation of unfired pressure vessels

DIN EN 13445-3:2026-12 specifies requirements for the design and calculation of unfired steel pressure vessels. It helps designers, plant engineers and inspection bodies design pressure vessels safely, taking into account pressure, temperature, material behaviour and other loads. The standard is part of the DIN EN 13445 series and provides a key basis for implementing the European Pressure Equipment Directive.

What is DIN EN 13445-3 about?

The standard describes the basic criteria and calculation methods for the design of unfired pressure vessels prior to commissioning. It focuses on wall thickness calculations, allowable stresses, and strength, fatigue and stability assessments. It also includes provisions for shells, dished ends, flanges, openings, nozzles, heat exchangers, vessel supports and other pressure-bearing components. With appropriate adaptations, the methods can also be used for analytical assessments during operation.

Topics covered

• Basic design criteria for unfired pressure vessels
• Allowable stresses and wall thickness calculation
• Shells, dished ends, cones and transition pieces
• Flanges, nozzles, openings and reinforcements
• Protection against corrosion and erosion
• Design for internal and external pressure
• Strength, stability and fatigue assessments
• Welded joints and weld joint coefficients
• Shell-and-tube heat exchangers and other pressure-bearing internals
• Vessel supports, support skirts and anchorages

Practical relevance

Unfired pressure vessels are used in sectors including the chemical industry, energy technology, process engineering, and machinery and plant engineering. DIN EN 13445-3 provides a consistent basis for calculation, safety verification and structural design and supports the reliable sizing of pressure-bearing components.

The comprehensive rules for different load cases and assessment methods are particularly relevant. They enable the systematic evaluation of vessel designs and support the implementation of Pressure Equipment Directive requirements in a traceable manner.

Changes compared with DIN EN 13445-3:2021-12

The 2026 edition has undergone technical and editorial revision. The main changes include:

• Updated normative references
• Correction of an equation for austenitic steels in Table 6-1
• Revised rules for openings in shells and dished ends
• Updated provisions for loads other than pressure and fatigue analysis
• Revision of several annexes on welded joints, analysis methods and fatigue assessments
• Addition of new normative annexes NA to ND on structural hot-spot stresses, cycle counting, fatigue life of partial penetration welds and stress concentrations
• Revision of Annex ZA

Target audience

• Pressure vessel designers
• Mechanical and process engineers
• Manufacturers of unfired pressure vessels
• Plant engineering companies
• Stress analysis engineers and structural strength specialists
• Welding engineers
• Inspection and supervisory bodies
• Pressure equipment experts
• Quality assurance and pressure equipment conformity professionals

Conclusion

DIN EN 13445-3:2026-12 provides the key basis for the design and calculation of unfired steel pressure vessels. The revised calculation methods and new normative annexes support the safe design of modern pressure vessels in compliance with the directive.

This document replaces DIN EN 13445-3:2021-12 .