环氧套筒修复含环向表面裂纹管道的试验研究与安全评定

发布时间：2018-03-11 07:00

本文选题：管道环向表面裂纹　切入点：应变特征　出处：《西南交通大学》2017年硕士论文　论文类型：学位论文

【摘要】：油气管道在我国形成了一个庞大的管道输送网络体系。随着服役年限的增加,油气管道显现出各种焊接类、材料类、腐蚀类缺陷。管道修复已经成为油气运输过程中的一项必不可少、经常性的工作,每年需投入大量的人力物力。裂纹嘴张开位移(CMOD)对于表面裂纹是一个公认的断裂参量,管道修复之后,管道表面裂纹被修复材料覆盖,CMOD很难测量,无法评估修复效果。而修复前后,应变均可用应变计测得。所以本文设想探索裂纹周边区域的应变特征,建立应变变化趋势与CMOD变化趋势的关系,用应变趋势评估环氧套筒对环向表面裂纹的修复效果。首先,开展了含环向短裂纹管道内压+弯矩的加载试验,研究了裂纹周边区域的应变特征。研究结果表明:裂纹中部轴向应变随弯矩增大,存在由正变负,不断减小的趋势。之后,开展了含环向90度等深裂纹管道的内压+弯矩加载试验。试验采用了线性可变差动变压器测量CMOD,并通过测试裂纹两侧电压,动态监测裂纹起裂对应的载荷条件。通过分析试验数据,验证了裂纹中部轴向应变随弯矩增大而不断减小的非偶然性。研究了 CMOD与裂纹中部轴向应变的关系,结果表明:CMOD与裂纹中部轴向应变存在一定的线性关系。为了进一步研究裂纹中部轴向应变与CMOD之间的关系,进行了含环向120度等深裂纹管道内压+弯矩加载试验,结果表明:环向120度等深裂纹的CMOD与裂纹中部轴向应变也存在一定的线性关系。由此建立了应变变化趋势与CMOD变化趋势的关系。最后,通过环氧套筒修复试验,对比修复前后裂纹中部轴向应变随弯矩的变化趋势,验证了用裂纹中部轴向应变趋势评估环氧套筒对管道环向表面裂纹修复效果的可行性。为了研究不同内压+弯矩组合载荷下管道环向表面裂纹的安全性,用英国标准BS7910对试验一中母材裂纹进行初步安全评定,得到含环向表面裂纹管道的容许载荷,并计算了不同内压+弯矩组合载荷下各评定点的安全裕量。根据试验一中得到的裂纹中部轴向应变,也计算了不同内压+弯矩组合载荷下裂纹的安全裕量,并将两种方法得到的安全裕量进行对比。
[Abstract]:Oil and gas pipelines have formed a huge pipeline transportation network system in China. With the increase of service life, oil and gas pipelines show various types of welding and materials. Corrosion defects. Pipeline repair has become an essential and regular work in oil and gas transportation, which requires a lot of manpower and material resources every year. Crack mouth opening displacement (CMOD) is an accepted fracture parameter for surface cracks. After repairing the pipeline, the surface crack of the pipeline is hard to be measured by the repair material covering with CMOD, and the repair effect can not be evaluated. However, the strain can be measured by strain gauge before and after the repair. So this paper assumes to explore the strain characteristics of the area around the crack. The relationship between strain change trend and CMOD change trend is established, and the effect of epoxy sleeve on repairing toroidal surface crack is evaluated by strain trend. First, the loading test of internal pressure bending moment of pipe with short ring crack is carried out. The strain characteristics of the region around the crack are studied. The results show that the axial strain in the middle of the crack increases with the bending moment. The internal pressure bending moment loading test of the pipe with circumferential 90 degree isodyne crack was carried out. The linear variable differential transformer was used to measure the CMOD, and the voltage on both sides of the crack was measured. The load conditions corresponding to crack initiation are dynamically monitored. By analyzing the experimental data, it is verified that the axial strain in the middle of the crack decreases continuously with the increase of bending moment. The relationship between CMOD and axial strain in the middle of the crack is studied. The results show that there is a linear relationship between the axial strain and the axial strain in the middle of the crack. In order to further study the relationship between the axial strain in the middle of the crack and CMOD, the internal pressure bending moment loading test of the pipe with circumferential 120-degree iso-deep crack is carried out. The results show that there is a linear relationship between the axial strain in the middle of the crack and the CMOD with the circumferential 120-degree isodyne crack. The relationship between the strain trend and the CMOD variation trend is established. Finally, the repair experiment of epoxy sleeve is carried out. The variation trend of axial strain along with bending moment in the middle of crack before and after repair is compared. The feasibility of evaluating the effect of epoxy sleeve on repairing annular surface crack of pipeline with axial strain trend in the middle of crack is verified. In order to study the safety of annular surface crack of pipeline under different internal pressure and bending moment combination load, By using British standard BS7910 to evaluate the safety of base metal crack in test No. 1, the allowable load of pipe with circumferential surface crack is obtained. The safety margin of each assessment point under different internal pressure bending moment combined loads is calculated. According to the axial strain in the middle of the crack obtained in experiment 1, the safety margin of the crack under different internal pressure bending moment combination loads is also calculated. The safety margin obtained by the two methods is compared.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE973;O346.1

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