ABSTRACT
Summary 8 6 4.1 Introductio n an d Layou t o f th e Standar d 8 7
4.1.1 Constructio n categorie s 8 9 4.2 Materia l Propertie s an d Allowabl e Desig n Stresse s 9 0 4.3 Th e Basi c Concep t o f Desig n b y Rul e 9 2
4.3.1 Are a replacemen t fo r nozzle s (Appendix F o f B S 5500 [4.1] ) 9 2
4.3.2 Maximu m stres s limitatio n fo r nozzle s (Section 3.5. 4 o f B S 5500 [4.1] ) 9 3
4.3.3 Shakedow n criteri a fo r nozzle s (Appendix L o f B S 5500 [4.1] ) 9 4
4.3.4 Maximu m stres s criteri a fo r flanges (Section 3. 8 o f B S 5500 [4.1] ) 9 5
4.3.5 Shap e imperfection s 9 6
4.3.6 Pressur e vesse l head s (Section 3.5. 2 o f B S 5500 [4.1] ) 9 6
4.4 Typica l (Hidden ) Criteri a i n Desig n b y Rul e 9 7 4.5 Th e Basi c Concep t o f Desig n b y Analysi s 9 8 4.6 Multi-Axia l Stres s State s 9 8 4.7 Stres s Categorie s 10 0
4.7.1 Exampl e o f a nozzl e i n a spherica l vesse l 10 2 4.8 Derivatio n o f Allowabl e Stres s Limit s 10 4 4.9 Relationshi p o f th e Stres s Limit s t o th e Variou s Categorie s 11 0 4.10 Comment s o n th e Desig n b y Analysi s Approac h 11 3
4.10.1 Genera l 11 3 4.10.2 Analyse s base d o n numerica l analysi s 11 4 4.10.3 Specia l cas e o f therma l expansio n stresse s
and pipewor k 11 6 4.10.4 Assumption s an d limitation s 11 7
4.11 Fina l Summar y 11 8 References 11 9 Appendix: Larg e Displacemen t Effect s i n Thi n Cylindrica l
Vessels Unde r Pressur e 12 0
The mai n philosoph y o f virtuall y al l nationa l desig n standard s i s base d on th e concept o f design-by-rule. Indeed , th e approach ha s bee n enshrine d in pressur e system s desig n standard s fo r s o lon g tha t i t i s par t o f th e culture o f th e industry . Essentially , i t involve s relativel y simpl e calcula - tions t o arriv e a t basi c scantling s vi a a n allowabl e standardise d desig n stress. Thereafte r componen t detail s ar e deal t wit h b y stric t adherenc e to specifi c rule s delineate d i n th e standard . Th e origin s o f th e rule s ar e not alway s obviou s bu t the y usuall y incorporat e considerabl e experience .
