Topics: Code Updates

PD 5500 Recent Code Updates

PD 5500 is the pressure vessel design and fabrication code by the British Standards Institution. Like ASME, it received some updates over the past year (Amendment 2 updates from the 2021 code) that are pertinent to know for those fabrication managers or welders operating out of the UK.


2021 Amendment 2 Code Changes to PD 5500

The code changes to PD 5500 encapsulate a variety of sections and appendixes.

These changes include new guidance on flange connections, weld joints, curves, nozzle junctions and stress limits, which are helpful to pressure equipment designers and engineers.

Additionally, throughout several sections of the code, changes occur where pi has replaced a numerical value. For instance, 0.785 has been replaced with pi/4 and 1.57 with pi/2, and so on. This change helps to increase the accuracy of those calculations.

Changes to Bolted Flange Connections

In section 3.8.1, Bolted Flanged Connections, a note has been added that says Fillet welded pipework flanges shall not be used above 370 °C. While this is a small change, this applies to any design of a non-integral slip on flanges.

Changes to Non-destructive Testing

In Section 5.6, Figure 5.6-1, Illustration of Welded Joints for Non-destructive Testing, has been updated to display further connection types for Type A and B joints.


Changes to Annex D and Annex G

Changes have occurred across the entire section of Annex D, like the requirements for vessels designed to operate below 0 °C. The most significant ones include Section D.5 and D.6, where notes have been added to further clarify the requirements.

Additionally, the data for the curves in Figure D.1 has changed considerably, which will affect the required impact test temperature.

In Annex G, specifically section G.2.5.5, the calculation for the maximum stress value at a sphere or nozzle junction due to the application of shear load, has been changed to include the effects of a torsional moment MT. This update increases the shear stress value that is calculated.

Additionally, when using the alternate rules for local loads on circular nozzles in spherical and cylindrical shells in Annex G section G.2.8, the formula for the interaction of loads (G.2.8-13) has been changed to align with the formula (16.4-15) in EN13445-3.

Changes to Construction Category 3

In section, when designing using Construction Category 3, the limit for design stress of Rm/5 is now applicable for steels in material group 11 in addition to those in group 1.

Why Designing PD 5500 Compliant Vessels with Software Matters

Keeping up with the latest code updates can be challenging. Fabrication software like Finglow helps designers and engineers design code-compliant pressure vessels and heat exchangers with built-in PD 5500 code assistance.

Download the documentations

Designing outside of the UK? In conjunction with PD 5500, Finglow also provides code assistance for EN13445 or ASME Section VIII, Div. 1 and 2 as well.

Schedule your free demo today to see just how easy it is to design code-compliant pressure vessels.

Written by Wayne Batizovszky

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