FRACTURE ASSESSMENT PROCEDURE OF API 5L GAS PIPE STEELS POSTUPAK PROCENE LOMA ZA API 5L ČELIKE GASOVODA

The fracture assessment procedure of API 5L gas pipe steels is analysed from the viewpoint of notch fracture mechanics. The procedure is determined by the interaction between the material failure curve and the notch driving force. The material failure curves, based on three-parameter fracture criterion of (K-T-A3) are determined by experimental tests for different laboratory specimens. The notch driving force consisted in modelling a real pipe with different geometry with a surface longitudinal notch submitted to internal pressure. The extrapolated points of the notch driving force to the material failure curve showed three critical parameters (K,c - Tef - A3ef,c) of fracture resistance of pipe steels. These values could be applied as an important engineering parameter for structural integrity assessment of pipelines during long-term operation. Kljucne reci • procena loma • kriva otkaza materijala • sila rasta zareza