ASME standard · reference card
Does ASME Section VIII, Division 1 govern the vessel, or does Division 2 apply instead? Scope decision flow for the by-rule pressure-vessel code and the codes it invokes for welding and NDE.
Section VIII, Division 1 is the by-rule pressure-vessel construction route, and the decision that sits above everything else in it is one most fabrication questions assume was already made correctly: which division actually governs. Division 1 and Division 2 are not a simple/complex split of the same rules — different allowable-stress bases, different mandatory examination logic — and mixing a Division 1 stress assumption with a Division 2 inspection plan does not produce a hybrid that satisfies either.
Inside Division 1 itself, the code qualifies nothing on its own. Welders and procedures qualify under ASME Section IX, and Division 1 layers its own joint-efficiency and examination-extent rules on top of a qualified WPS rather than replacing it. The other tangle is joint efficiency and examination: they are decided together, since the design’s stress allowable assumes a specific level of NDE was actually performed.
Therness equipment measures the process variables an Inspector’s paper trail otherwise takes on faith — heat input, interpass temperature and preheat — on the thick, multi-pass seams typical of vessel fabrication, tied to the welding process record.
| Question | If yes | If no |
|---|---|---|
| Is the equipment a pressure vessel, rather than a fired boiler or atmospheric storage tank? | Continue within ASME BPVC Section VIII. | A fired steam boiler is Section I; an atmospheric storage tank is API 650. |
| Has Division 1 (design by rule) been selected over Division 2 or Division 3? | This entry's rules apply. | Division 2 and Division 3 use their own stress and NDE bases; do not mix bases across divisions on one vessel. |
| Are welders and procedures qualified under ASME Section IX for the material, thickness and process? | Proceed under the qualified WPS. | Qualify first; Section VIII does not qualify anything on its own. |
| Does the design's joint efficiency match the examination extent specified for that joint? | Design and inspection plan agree; proceed. | Reconcile them before fabrication; the two are linked choices, not independent ones. |
Conformity is decided by inspection and testing against the criteria the standard and the contract set. The records below are evidence that the process was held where it was qualified; they support an inspection result, they never replace one.
| Requirement | Record produced | Source |
|---|---|---|
| Evidencing heat input and interpass temperature stayed inside the qualified WPS on a thick vessel seam | Arc energy and interpass temperature computed and measured per pass, continuously | WeldTrace |
| Confirming preheat was reached and held before the arc struck | Full-field thermal image of the joint immediately before and through welding | HeatCam IR-C |
| A per-weld record available to the Authorized Inspector alongside the NDE report | Timestamped process export tied to weld and joint identifier | HeatCore AI |
No. The divisions use different stress and NDE bases; mixing a Division 1 stress assumption with a Division 2 inspection plan satisfies neither.
No. Welders and procedures qualify under ASME Section IX; Division 1 layers its own rules on top of that.
ASME BPVC Section VIII, Division 3 — a separate rule set, not a stricter version of Division 1.
Therness records what the machine actually delivered on every weld — parameters, thermal signature and a per-weld trail — so a conformity argument rests on measurements instead of recollection.
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