If your radiographic density determinations are correct, result a slight negative radiographic contrast (-0.04, very close of the threshold of human eye perception: 0.02). This means to evaluate the following possible imperfections: 1. weld: a. metallic inclusions (tungsten or copper,depending the welding process); b. weld spatter; c. a small higher thickness. 2. film handling and manipulation (artifacts). All the other imperfections possible in welds create a positive radiographic contrast (including LoF). Imperfections 1.b); c) and 2. can be easy verified by VT of weld or viewing, by reflexion, the surface of the film. Imperfection 1.a): - tungsten inclusion, specific for TIGW, creates a high negative contrast indication (> - 0.2, depending the radiation source energy) and can not be considered. -copper inclusion create a small negative contrast indication (a little higher specific weight than steel) and can be considered. There are not acceptance criteria depending the contrast. This helps, only, for imperfection (discontinuity) diagnosis. A UT discontinuity indication of 20 % DAC (DAC-14 dB) is not important (considered, for example, by EN 1713 as insignificant and by ASME VIII, app. 12 at the upper limit of non-evaluation), so could be associated to the upper mentioned copper inclusion. --- On Thu, 4/15/10, Shashank Vagal <nach_sam@yahoo.com> wrote:
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