打孔管道焊接修复结构承压能力的全尺寸实验评价

将打孔管道的焊接修复结构区分为单开孔和密集开孔两种类型。完成了一组管道修复结构的全尺寸爆破与疲劳实验,测量了修复结构中的应变分布,分析了应力集中、屈服极限压力和爆破压力等因素。结果表明,修复结构的屈服极限压力和完好管道相比有所降低,最低值为完好管道屈服极限压力的85%,而各种修复结构的爆破压力基本相同,约为完好管道爆破压力的96%。单孔管道的破裂位置均远离焊接结构处,多孔管道的爆破发生在两管帽之间,说明多管帽修复结构不利于管道承压。修复结构存在一定程度的应力集中,环向应力集中系数最大为1.65,轴向应力集中系数最大为2.25。对于经过5 000次循环载荷的修复结构,其屈服极限压力、爆破压力及爆破位置与未经过疲劳载荷的修复结构情况基本相同,表明修复结构有较好的抗疲劳破坏能力。通过试验验证了打孔管道修复结构的承压能力。

Full size experimental assessment on loading capability of welding-repaired pipelines with drilled holes

The welding-repaired pipelines are identified as two types of a single hole drilled on pipeline and several holes drilled in short span. A set of the full scale burst and fatigue experiments for the two kinds of repaired pipelines were conducted. The strain distributions were measured, and the stress concentration and yield limit load and burst pressure were analyzed. The results showed that the yield limit pressure of the repaired pipelines were lowered. The lowest yield limit pressure of repaired pipelines was 85% of that of the perfect pipelines, while their burst pressure was up 96%. The burst of pipeline was a ductile fracture resulted from the maximal shear stress. On the pipelines with a single hole, the burst occurred far from the welding sites, while on the pipelines with several holes drilled in short span, the burst occurred between the two adjacent tube caps welded on the drilled holes. Multi-cap repair is disadvantageous to the normal loading capability. Welding repairing process could result in the stress concentration. The maximum concentration coefficient of the hoop stress was 1.65, and the maximum axial stress was 2.25. The yield limit pressure, burst pressure and location of the repaired pipelines subjected to 5000 cyclic loading tests in high stress level were same as those of the repaired pipeline that did not experience cyclic loading, which indicated that the repaired pipelines have good anti-fatigue capability. The full-size experiments demonstrated the loading capacity of the repaired pipelines.