单孔管道修复结构的全尺寸试验

管道现场抢修常用两种修复方式,一种是扣帽子,一种是补板.分别对扣帽子和补板方式修复的φ711×10管道进行全尺寸爆破试验,测量修复管道中的应变分布.结果表明,焊接帽子或补板的存在使管道修复部位的应力分布不均匀,出现一定程度的应力集中.焊接帽子和焊接补板修复的管道的屈服强度相近,约为完好管道屈服强度的85%.但焊接"帽子"对小孔处的变形约束作用小于焊接"补板"对小孔处变形约束作用,在管材没有足够韧性的情况下,容易引起管道在开孔处撕裂;焊接帽子和焊接补板修复的管道的爆破压力均低于但接近于完好管道的爆破压力,管道的破裂位置均远离焊接帽子或补板处,爆破是由于最大剪应力引起的韧性破坏.试验结果可以为打孔管道修复结构的安全性评价提供参考.

FULL SCALE EXPERIMENT OF WELDING REPAIRS OF PIPELINES DRILLED A SINGLE HOLE

There are two ways to repair the damaged pipelines in fields.One is welding a short tube with a cap.Another is welding a patch.Full scale experiments were conducted to assess the loading capability of the repaired pipelines.The pipelines repaired by welding a tube cap or a patch were pressured to burst failure.Strain gages have been used extensively to monitor stress state in full scale pipeline tests.It was showed that welding a tube cap or a patch resulted in the non-uniform stresses distribution and the stress concentration in the extent.These two kinds of the repaired pipeline have almost the similar yield limit pressure which are equal to about 85% of that of pipelines that were not drilled.But,the pipeline repaired with a short tube can be fractured around the hole in the case of low toughness of pipeline steel because welding a short tube has less enforcements to the deformation near the hole in pipeline than welding a patch.The burst pressures in these tests are close to the burst pressure of pipeline which has not been damaged,whereas the location of burst failure is far from where a short tube or a patch is welded.The burst is a ductile fracture by maximum shear stress.These experimental studies can be a reference to the safety assessment of the repaired pipeline.