Using fracture mechanics approaches and received experimental data on the regularities of hydrogenating of pipeline steels, the criteria for assessment of safe operation of pipeline with crack-like defects in hydrogenous operating environment of different composition were proposed and proved.
The analytic relation for description of fatigue crack growth resistance diagram of pipeline steels in hydrogenous environments was proposed and experimentally verified. This formula takes into account the local hydrogen concentration in the crack tip and also the average hydrogen concentration in bulk of metal.
On this ground the diagrams of critical dimensions of defects were calculated for pipelines of different size and different level of hydrogenation. These diagrams serve the basis for assessment of workability and durability of pipelines in given operating conditions.
The version of computer's expert program for technical diagnostics of structural elements workability of pipeline systems for hydrogen transmission was developed.
The specialized laboratory with computer’s operation of burst test process of structural elements of pipeline systems for transmission of gaseous hydrogen and its mixtures was developed. This laboratory provides the conducting of investigations in automatic mode.
Keywords: Pipeline elements; Hydrogen-charging of metal; Bulk and local hydrogen concentration; Crack growth resistance; Crack growth rate; Stress intensity factor; Threshold and critical size of defect; Diagram of pipeline fracture risk; Admissible defects