在小径管环向对接焊接接头射线检测中，按照JB/T 4730.2—2005标准规定，由于结构原因不能进行多次透照时，可采用椭圆成像或重叠成像方式透照一次。在小径管环向对接焊接接头射线检测时，由于射线穿透的管件厚度变化大，因此底片上所反映的缺陷畸变的长度和黑度不同。研究这些变化的特点，可以正确评定底片上的缺陷，并对焊缝质量的评定尽可能准确无误，根据这些特点将透照成像后的椭圆影像和重叠影像分为四个评定区域进行了分析。

In narrow-bore tube circumferential butt welded joints radiographic test, in accordance with the standard JB/T 4730.2—2005, if multi transilluminations can not be performed due to structural reason, a single transillumination through oval or overlap imaging can be used for the same result. While radiographic testing the narrow-bore tube circumferential butt welded joints, since the thickness of tube that rays penetrate is different, therefore the length and blackness of defect distortion reflected on the film is different. Research about the characteristics of the changes can assess the defects on the film accurately, thus leading to an as accurate as possible assessment of the quality of the weld. According to these characteristics, the transillumination oval and overlay images were divided into four regions to analyze.