Assessment of pressure vessel load capacity in the presence of cracks

Abstract

The paper illustrates the structural assessment of an investigated pressure vessel, made of low-alloyed high strength steel, with an external surface crack located on the shell wall. In order to assess the remaining strength and the resistance to stable crack growth, the J-integral is experimentally measured at operating temperature of -40°C. The compared crack driving force and material resistance to crack growth have determined the size of the zone of stable crack development, as well as the critical crack length. Also given is the pressure vessel calculation code by applying the theory of finite elements to linear-elastic material behaviour. Critical pressure values are calculated by analytical and numerical procedures and show good agreement.

U radu je prikazana ocena integriteta ispitne posude pod pritiskom izrađene od niskolegiranog čelika povišene čvrstoće sa spoljašnjom površinskom prslinom na zidu omotača. Da bi se ocenila preostala čvrstoća i otpornost na stabilan rast prsline, eksperimentalno je izmeren J-integral na radnoj temperaturi od -40°C. Poređenjem sile rasta prsline i otpornosti materijala na rast prsline određena je veličina zone stabilnog rasta prsline kao i kritična veličina prsline. Prikazan je i proračun posude pod pritiskom primenom teorije konačnih elemenata za linearno-elastično ponašanje materijala. Kritične vrednosti pritisaka izračunate analitičkim i numeričkim postupkom pokazuju dobro slaganje.