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油气管道站场用管要求具有较高的低温抗断裂性能,尤其是三通等管件的壁厚较大,尺寸效应显著。为了确定低温服役的X80大口径三通的适用温度和壁厚,通过夏比冲击、落锤撕裂和三点弯曲试验研究了X80大口径三通的低温断裂韧性和尺寸效应,并利用失效评估图技术进行安全评估。结果表明:X80大口径三通具有较好的低温夏比冲击性能,但抵抗低温裂纹长程扩展的落锤撕裂性能较差。试验温度高于-20℃时,随着壁厚增大,DWTT断口剪切面积减小,在20℃、0℃和-10℃试验温度下的50%剪切面积临界壁厚分别为26 mm、25 mm和22 mm。利用三点弯曲试验测得的低温断裂韧度计算的X80三通失效评估点均在安全区域内,而且有一定的安全裕量。
Oil and Gas Pipeline station tube requirements have a higher low temperature anti-fracture properties, especially the tee and other pipe fittings larger wall thickness effect is significant. In order to determine the suitable temperature and wall thickness of the X80 large-caliber tee used at low temperature, the low-temperature fracture toughness and size effect of the X80 large-caliber tee were studied by Charpy impact, drop weight tear and three-point bending test. Figure technology for safety assessment. The results show that the X80 large diameter tee has good low temperature Charpy impact properties, but the drop weight tear resistance is poor against the long-term expansion of the low temperature crack. When the test temperature is higher than -20 ℃, the shear wall area of DWTT decreases as the wall thickness increases. The critical wall thickness of 50% shear area at 20 ℃, 0 ℃ and -10 ℃ are respectively 26mm , 25 mm and 22 mm. X80 tee failure evaluation points calculated from the low temperature fracture toughness measured by the three-point bending test are both within the safe area and have a certain safety margin.