EN 13480-3 Clause 7.2.3 Possible ambiguous result

Red-Bag is member of the CEN/TC 267/WG3 workgroup. This workgroup is responsible for the maintenance and improvements of the EN 13480-3 Industrial Piping and Pipelines standard.

Red-Bag is developer and provider of software for the calculation according the EN 13480-3. The software is used by Notified Bodies to assess the validity of the engineering calculations submitted by plant owners, engineering companies and manufacturers.

During the development of the calculation software, and also as part of the standard development work for CEN, we at Red-Bag sometimes find room for improvements. This can be an inconsistency, a statement leading to ambiguous results or a mechanical non-optimal result in the standard.

Most of the background of the calculation standards are based on the still existing national standards. The basics for these national standards are many years old. We have taken the opportunity, because of this last fact, to look into all of the calculations with help of the current software tools available.

Welded flat head

The EN 13480-3 Clause 7.2.3 is a calculation for flat heads. Due to the note at the end of Clause stating:
“When the values of e_eq / D_i and p_c / f_1 result in a value less than 0.3, only the first term of equation (7.2.3-6) applies.”
The possible two valid values for the calculation of the MAWP will occur.

A full report explaining the cause and the problem of this possible ambiguous result has been submitted to the CEN/TC 267/WG3 workgroup. Some highlights of the report are below:

Image - component dimensions

Image - two areas of valid results

Image – FEM analysis of stress, square flat plate (elastic/plastic calculation by WentzelDynamics)

Image – FEM analysis of stress, rounded flat plate (elastic/plastic calculation by WentzelDynamics)

Image - FEM analysis of stress, not showing extreme stress (elastic/plastic calculation by WentzelDynamics)

Image - FEM analysis of strain, showing extreme strain leading to failure (elastic/plastic calculation by WentzelDynamics)

The above-mentioned report is just recently submitted, therefor no further details are given here.
Red-Bag will execute each major finding as a separate internal project for which we are seeking support. An internal project section will be part of this website where current issues will be highlighted. For more information or potential sponsorship please contact us via the contact form on this website.

Sponsor: WentzelDynamics