Code Scope

Module from the Pressure Vessel Engineering Curriculum curriculum.

Module 1 - ASME VIII Code Scope and Classification · Learning Objectives · 1. State ASME Section VIII Division 1 scope exclusions (UG-1, U-1) · 2. Differentiate Division 1 vs 2 vs 3 (design rules, allowable stress basis) · 3. Identify U-stamp, UM symbol, and UV (PSV) stamp requirements · 4. Apply National Board (NBIC) registration and jurisdictional requirements · 5. Recognize when 49 CFR DOT or ASME B31.1 Power Boiler applies instead · ASME VIII Division Comparison

Parameter	Division 1	Division 2	Division 3	Typical Use	Safety Basis
Design method	Design-by-rule	Design-by-analysis	Design-by-analysis + NDE	Most process	Formula + factor 3.5
Allowable stress	UTS/3.5 or Y/1.5	UTS/2.4 or Y/1.5	UTS/2.4	Heavy wall	Higher for Div 2
Design pressure range	Any (typical <3000 psi)	Any (often >500 psi)	>10000 psi	Syngas, HP hydrogen	Test to 1.3xMAWP
Fabrication NDE	Spot RT typical	100% RT or UT	100% volumetric	Special service	Lower inherent NDE
Design margins	Higher	Moderate	Lowest	Match rigor	Match inspection
Stress analysis	Not required generally	FEA stress classification	Detailed FEA + fatigue	CALC	Per class
Typical Refinery Vessel Classification
Vessel	Typical P (psig)	Typical T (F)	Division	Material	Notes
Atmospheric tower	15-50	650-750	Div 1	SA-516-70	Thick wall at base
FCC reactor	30-50	950-1050	Div 1	SA-387 Gr 11 clad	Erosion liner
FCC regenerator	25-40	1250-1350	Div 1	SA-387 Gr 11	Refractory lined
Hydrotreater reactor	800-2500	650-800	Div 1 or 2	SA-387 Gr 22	Chrome-moly
Hydrocracker reactor	1800-2500	750-850	Div 2 (cladded)	SA-336 F22V or F22	Heavy wall
H2 synthesis converter	3000-5000	900-1000	Div 2 / Div 3	2.25Cr-1Mo-V	Advanced alloy
Amine absorber	100-250	80-160	Div 1	SA-516-70 PWHT	Alkaline SCC risk
KO drum	150-300	100-200	Div 1	SA-516-70	Standard drum

Source: Pressure_Vessel_Engineering_Curriculum_v1.xlsx · Sheet: Code Scope

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