小直径超薄壁管纵缝焊接的主要问题是烧穿，解决这个问题的关键是严格控制焊接接头的装配质量及焊接工艺。
Burn through is the main problem of longitudinal seam welding of ultra-thin tube with small diameter. Assembly of the joint and welding technology are the key to solve the problem.
采用纵剪带钢生产小口径螺旋焊管时，超声波检验经常在焊缝的一侧发现缺陷波，而X射线拍片检验却很难发现。
The defects will be found in the seam side with ultrasonic inspection but hardly found with X ray inspection as the small diameter spiral pipe production with the split strip steel.
在分析常用低噪声快速光电探测器的基础上，选择pin光电二极管来探测氦氖激光纵模脉冲。
Based on analyzing common low noise and fast photodetectors, PIN photodiode is selected to detect He-Ne laser longitudinal mode pulse.
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