If you are certifying pressure equipment under the Pressure Equipment Directive, the strength calculation is not only an engineering exercise — it is a document someone else has to read, follow and accept. From Category II upwards, that someone is a notified body.
Knowing what they look for is often the difference between an approval that takes days and one that drags on for weeks. Here is what typically gets checked.
The right standard — and the right edition
The first thing verified is that the calculation follows an appropriate harmonised standard for the equipment — EN 13445 for unfired pressure vessels, EN 12952 or EN 12953 for boilers, EN 13480 for piping, EN 1591 for flanged joints — and that the edition used is the one applicable to the project. A calculation performed to a superseded edition will be questioned.
Design data that matches the rest of the documentation
Maximum allowable pressure, design temperature, corrosion allowance, dimensions and material grades are cross-checked against the drawings and the specification. Inconsistency here is one of the most common causes of rework: the calculation says one wall thickness, the drawing says another, and the reviewer has to stop and ask which is correct.
Materials and allowable stresses
The reviewer checks that the selected materials are permitted by the standard for the intended service, that the allowable stresses used correspond to the design temperature, and that material documentation (e.g. EN 10204 3.1 or 3.2 certificates) is consistent with what the calculation assumes.
Complete coverage of the pressure-bearing parts
It is not enough to calculate the shell. Heads, cones, openings and nozzles with their reinforcement, flanges, flat ends and — for boilers — tubes, headers and stays all have to be covered. Missing components are noticed quickly, because the reviewer works through the equipment part by part.
Load cases, including the test condition
Besides the design condition, the test pressure case is expected, and where relevant the operating conditions — plus fatigue or creep assessment where cyclic operation or elevated temperature makes it applicable.
Traceability — can the reviewer follow it?
This is the one that decides how smooth the review is. Every result should be traceable to the clause and formula in the standard it comes from, using the standard’s own nomenclature. A reviewer who can follow each step to its source can verify quickly. A report that produces numbers without showing where they come from invites questions — and questions cost time.
Common reasons reports come back
- Calculation inputs that do not match the drawings
- Components omitted from the scope
- Allowable stresses taken at the wrong temperature
- A joint coefficient inconsistent with the NDT level
- Missing test-pressure case
- No clear revision control — which version is the approved one?
- Results that cannot be traced back to the standard
Making the review straightforward
Most findings are not engineering errors — they are documentation problems. The calculation was right; the report just did not make it easy to verify.
That is why we built sPEeD-Analyze the way we did: every result references the exact formal expression in the applicable norm, using the same nomenclature as the standard, and the report comes out in a consistent structure with component overview, utilisation and pass/fail per part, and the project and approval fields already in place. The reviewer can follow it without having to reconstruct your reasoning.
If you would like to see what that looks like on one of your own cases, book a demo — we will run it live and show you the report it produces.
