**What is PD 5500 - Unfired pressure vessels about?**

PD 5500 is the UK’s national pressure vessels code, a new edition of which is published every three years.

In 2021 the code started a new three-year publishing cycle during which an annual update is published in the form of an amendment every September. PD 5500:2021+A2:2022 is the second annual update to the 2021 edition of the code.

**Who is PD 5500 - Unfired pressure vessels for?**

Mechanical engineers
Pressure vessel designers and design consultancies
Pressure vessel manufacturers
Pressure vessel inspection bodies in the oil and gas, petrochemicals, process plant and energy generation (including nuclear) industries

**What does PD 5500 - Unfired pressure vessels cover?**

PD 5500 specifies requirements for the design, manufacture, inspection and testing of unfired pressure vessels made from carbon, ferritic alloy, and austenitic steels. It also includes material supplements containing requirements for vessels made from aluminium, copper, nickel, titanium and duplex.

PD 5500:2021+A2:2022 brings together all the content released as amendments to the 2018 edition of the code, repackaged to start the new three-year publishing cycle, plus the latest amendments generated by committee members and user enquiries regarding the 2021 edition.

**Why should you use PD 5500 - Unfired pressure vessels?**

It’s an invaluable reference tool for the design and assessment of pressure vessels
Its use produces safer, more cost-effective pressure vessels
Subscribers receive an annual update each September
It can help users enter new markets, trade, increase trust and improve risk management
This version consolidates all the latest corrections, clarifications and technical changes that keep the code up-to-date, accurate and user-friendly

What’s new about PD 5500:2021+A2:2022?

The major technical and editorial changes in Amendment 2 to PD 5500:2021 (PD 5500:2021+A2:2022) are:

Revisions to definitions of material groups and sub-groups
Updates for low temperature applications, including clarification of the requirements for austenitic stainless steels at low temperature, revisions to Figure D.1 and the corresponding equation for as-welded components, clarification of the calculation of design reference thickness for vessels designed to operate below 0°c, as well as updates to Annex U on the use of fracture mechanics analyses
The addition of material group 11 for Category 3
Clarification of the requirements for light stiffeners on cylindrical shells subject to external pressure
Clarification of the equations for HG on suggested working forms for flange design
The addition of the basis for the allowable stresses on suggested working form (5) for a lap-type joint
The inclusion of guidance regarding inspection documents for materials for vessels subject to the requirements of the PED or PER
Clarification of the definitions of Type A and Type B welds
The addition of requirements for the orientation of impact test specimens
The addition of a calculation for shear stress due to a torsional moment for local loads on spherical shell/nozzle attachments
Clarification of requirements for welding for nickel and nickel alloys
Clarification of the requirements for welding and heat treatment for titanium and titanium alloys.
Additionally, various internal and external references have been updated

PD 5500:2021+A2:2022 PDF

Specification for unfired pressure vessels

Current

Published:

15 Sep 2022