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A Comparison of Pressure Vessel Codes: PD 5500, EN 13445, ASME VIII Div 1, and ASME VIII Div 2

Pressure vessels are containers that are designed to hold gases or liquids at a pressure above atmospheric pressure. They are used in a wide variety of applications, including power plants, chemical plants, and oil and gas production.


What are the reasons for the development of PD 5500 and EN 13445?

  • The need for lighter and more efficient vessels to meet the demands of the offshore oil and gas industry.

  • The desire to harmonize pressure vessel codes across Europe.

  • The need to improve the safety of pressure vessels.

PD 5500 is a British Standard that was first published in 1981. It is more flexible than the American Society of Mechanical Engineers (ASME) VIII Division 1 code, which is the most widely used pressure vessel code in the world. The first edition of EN 13445 was not as comprehensive as BS 5500, so the British pressure vessel standard continued to be available under the new reference PD 5500. PD 5500 has equal content, validity, and application to BS 5500, but it does not have the status of a "national standard". PD 5500 allows for higher allowable stresses and thinner walls, which can lead to lighter and more efficient vessels. However, PD 5500 also requires more rigorous inspection and non-destructive testing.


EN 13445 is a European Standard that was first published in 2002. It is similar to PD 5500, but it is more comprehensive and covers a wider range of pressure vessels. EN 13445 is also more harmonized with other European standards, such as the Pressure Equipment Directive (PED).

The development of PD 5500 and EN 13445 has helped to improve the safety and efficiency of pressure vessels. These codes are now widely used in Europe and around the world.


PD 5500 and EN 13445 are pressure vessel design codes that are used to design lighter and more efficient vessels.

  • PD 5500 is a British Standard that evolved from BS 5500. It removed weld joint factors and introduced three categories of construction. It also has a new, novel external pressure section and a loose-leaf format that allows for annual updating.

  • EN 13445 is a European Standard that is similar to PD 5500, but it is more comprehensive and covers a wider range of pressure vessels.

  • ASME VIII Div 1 uses a P number system to designate materials. The P number indicates the tensile strength of the material, and there are different P numbers for different types of materials.

  • PD 5500 and EN 13445 use a group number system to designate materials. The group number indicates the allowable stress of the material, and there are different group numbers for different types of materials.

  • PD 5500 allows for the use of a wider range of materials than ASME VIII Div 1 or EN 13445. This is because PD 5500 allows for the use of materials that are not specifically listed in the code, as long as they meet certain criteria.

  • EN 13445 requires the use of materials that are listed in the European Standards for plates, strips, bars, tubes, forgings, and castings for pressure purposes. This ensures that the materials used in EN 13445-compliant vessels are of high quality and meet the necessary safety standards.

In general, PD 5500 is the most flexible of the three codes when it comes to material selection. This makes it a good choice for applications where the use of a specific material is important. ASME VIII Div 1 is the most conservative of the three codes, and it is a good choice for applications where safety is the primary concern. EN 13445 is a good compromise between flexibility and safety, and it is a good choice for most applications.

Here are some additional key differences between the four codes:

  • Allowable stresses

    • PD 5500 and EN 13445 have higher allowable stresses than ASME VIII Div 1. This is because PD 5500 and EN 13445 allow for more rigorous inspection and non-destructive testing.

    • ASME VIII Div 2 also has higher allowable stresses than ASME VIII Div 1, but the inspection requirements are not as rigorous.

  • Joint efficiencies

    • PD 5500 and EN 13445 use more advanced joint efficiency factors than ASME VIII Div 1. This means that they can account for the effects of weld defects and other factors that can reduce the strength of a joint.

    • ASME VIII Div 2 does not use joint efficiency factors.

  • Safety factors

    • PD 5500 and EN 13445 use lower safety factors than ASME VIII Div 1. This is because they are based on more advanced analysis methods that take into account the effects of fatigue and other factors.

    • ASME VIII Div 2 uses the same safety factors as ASME VIII Div 1.


The choice of which code to use will depend on the specific application. If weight and efficiency are important, then PD 5500 or EN 13445 may be a good choice. If there is a need for a more conservative approach, then ASME VIII Div 1 may be a better option. And if the vessel is purpose-specific, then ASME VIII Div 2 may be the best choice.

It is important to note that this is just a brief overview of the key differences between the four codes. For more detailed information, please consult the specific codes.


Universal Engineering services(UES) can do Engineering of modular substations. Our Structural Engineers can design offshore container modules, skids packages, cargo baskets, steel structural frames, lifting analysis of offshore structures,etc to clients all over the middle east countries like UAE, Oman, Qatar, Saudi and Kuwait for petrochemical, power and oil and gas industry. We also offers reliable offshore and onshore design of structures as per D.N.V. 2.7.1 and we are diversified into Structural Design, Engineering & Analysis for the Industrial, Offshore and Oil & Gas industry.



**The content of this article is taken from web open source. The blogs are intended only to give technical knowledge to young engineers. Any engineering calculators, technical equations and write ups are only for reference and educational purpose.

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