论文部分内容阅读
1 双壁双影照相术的关键对于外径≤89mm(即3.5in.)钢管对接环缝射线照相时常常采用双壁双影的照相方法.众所周知,双壁双影照相时管子各部分的实际透照厚度变化幅度特别大.中心部分的透照厚度是个极小值,等于管子壁厚T的两倍(如果焊缝的余高不等于零,则还要加计余高);射线与管子内壁相切方向上的透照厚度最大;再往外,透照厚度迅速减小到零.透照厚度的大幅度变化必然导致焊缝影象黑度的大幅度变化.对管子环缝的照相胶片,首先要问黑度适宜的有效评定范围到底有多大?在大多数情况下,认为相隔90°的两次双壁双影照相即能实行对整圈焊缝的检验,换句话说,每次照相的有效评定范围应该不少于1/2周.
1 double-walled double-diphtheography of the key For the outer diameter ≤ 89mm (3.5in.) Steel docking ring seam radiography often used double-wall double-shadow photography method.It is well known that the double-walled double-photographic tube in various parts of the actual The transillumination thickness is particularly large and the transillumination thickness in the center is a minimum value equal to twice the tube wall thickness T (plus the remaining height if the residual height of the weld is not equal to zero) The transillumination thickness in the tangential direction is the largest, and then the transillumination thickness is rapidly reduced to zero.The drastic change of the transillumination thickness will inevitably lead to the drastic change of the image blackness of the weld.With regard to the photographic films, First of all, to ask what is the proper range of effective blackness assessment? In most cases, it is considered that double-walled double-dipole radiographs separated by 90 ° are capable of inspecting full-circle welds, in other words, Effective assessment should not be less than 1/2 week.