Re: [MW:4829] Radiographic film interpretation

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:

From: Shashank Vagal <nach_sam@yahoo.com>
Subject: [MW:4850] Radiographic film interpretation
To: materials-welding@googlegroups.com
Date: Thursday, April 15, 2010, 5:46 PM

Hi all,

In one RT film we have a 10-12 mm spot with density 3.13. The weld density is 3.17 and the parent metal density is 3.3. It is apparently interpass LoF in the 2nd fill pass after hot pass (confirmed by UT, where the indication ht is approx 20%of DAC). Is there any or what is the criteria for acceptance/rejection based on density difference?

Rgds,

Shashank Vagal

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