Safety analysis and design consideration for old and gas pipelines

摘要

The degradation in fracture toughness data during pipeline fabrication for oil and gas transportation industries is accounted for APIX70 grade steel plate.A reduction in CTOD value by 57 percent and 40 percent is measured after cold bending and welding respectively.The combined effect of the two manufacturing stages are still worse.The measured toughness data at different temperature and along two orientations is used for assessing safe operating pressure of two pipelines (x41 and x46 grades). The safe working pressure is estimated to be 52 kg/cm~2 and 73 kg/cm~2 for the grades.