array eddy current solution for small nozzles -尊龙凯时官网入口
2023-06-28 14:01 ytzx
1. difficulties in nozzle inspection
in early june 2023, inspectors from a petrochina refining & chemical enterprise detected flue gas around the thermocouple nozzles (fig.2) for internal temperature measurement of the hydrogenation reactor (fig.1) in the isomerization dewaxing unit of the no.3 refining department.
it was confirmed that leakage occurred at the inner nozzle of the vessel. after the unit was shut down for maintenance, the leakage point of the nozzle still could not be located by visual inspection, penetrant testing, and ultrasonic testing on the vessel wall surfacing zone.
图1 加氢反应器（红圈处为接管泄漏位置） 图2 热电偶接管结构图
at the invitation of the customer, our technical engineers rushed to the site with the portable multi-channel array eddy current detector to carry out inspection and pinpoint the leakage position.
the hydrogenation reactor is equipped with thermocouple nozzles arranged in four layers, with three nozzles for each layer, totaling 12 nozzles. part of each nozzle extends into the interior of the vessel, and the outer end is connected to instruments. all nozzles are connected to the vessel wall by surfacing welding.
2. inspection procedure
array eddy current testing was carried out separately on four welds of the problematic small nozzles. typical crack waveform signals were rapidly identified at the weld of the ø50/ø32 reducing section, and the defect position was marked with a black marker pen (fig.3).
after grinding the marked area, one tiny crack was found via penetrant testing (fig.4). following further grinding and repeated penetrant testing, multiple cracks were detected at the marked position (fig.5).
图3 阵列涡流检测缺陷位置标记
图4 渗透检测发现细小裂纹 图5 再打磨后渗透检测发现多处裂纹
in addition, we inspected the remaining 11 small nozzles of the hydrogenation reactor, and crack defects were found on one of them. the defects were removed by grinding, and it was confirmed that the cracks belonged to surface defects.
3. conclusion
array eddy current testing technology can quickly locate defect positions of small nozzles without grinding pretreatment. compared with penetrant testing, magnetic particle testing, ultrasonic testing and other inspection methods, it requires no surface treatment on the tested component and no couplant application, featuring environmental friendliness and zero pollution.