管道漏磁内检测中疑似分层缺陷的确认与评价

Confirmation and Evaluation the Suspected Delamination Defects Found in A Natural Gas Pipeline During in-Line Inspection

珠三角某天然气管道在进行管道漏磁内检测缺陷开挖验证检测过程中,发现了管道疑似分层缺陷。经过对钢管出厂资料和驻场监造资料进行核验,采用X射线拍片、超声波相控阵、超声测厚、超声波平底孔双晶直探头等方式对疑似分层缺陷进行检测,明确了管道缺陷类型,并根据检测结果对管道缺陷进行了适用性评价。结果表明:疑似分层缺陷尺寸较小且彼此独立,未超过SY/T 6423.4-2013《石油天然气工业钢管无损检测方法第4部分:无缝和焊接钢管分层缺欠的自动超声检测》和GB/T 9711-2011《石油天然气工业输送钢管交货技术条件第2部分:B级钢管》中要求可记录的缺陷尺寸及缺陷当量,现场管道缺陷类型属于密集型夹渣缺陷,采用SY/T 6477-2017《含缺陷油气管道剩余强度评价方法》对缺陷进行适用性评价,均属于可接受缺陷。

Suspected delamination defects were found in a natural gas pipeline in the Pearl River Delta during in-line inspection.After checking the delivery data and on-site supervision data of steel pipe,X-ray detection of weld,ultrasonic phased array,ultrasonic thickness measurement,ultrasonic flat bottom hole double crystal straight probe and other methods were used to detect the suspected delamination defects.The types of pipeline defects were identified,and the applicability of pipeline defects was evaluated according to the detection results.The results show that the suspected delamination defects are small and independent,It does not exceed the recordable defect size and defect equivalent specified in syt6423.4-2013"Petroleum and natural gas industries-NDT methods of steel tubes-Part 4:Automated ultrasonic testing of seamless and welded steel tubes for the detection of laminar imperfections"and gbt9711-2011"Petroleum and natural gas industries-Steel pipe for pipelines-Technical delivery conditions-Part 2:Pipe of requirements class B".The defect type of on-site pipeline belongs to dense slag inclusion defect.According to fitness for purpose of syt6477-2017"Remaining strength evaluation for oil&gas pipeline with flaws",the above defects are acceptable.