Ravi,
Following is the extraction of ASTM E94:
Clause 15.2 The radiographic image of an object or feature within
an object may be larger or smaller than the object or feature
itself, because the penumbra of the shadow is rarely visible in
a radiograph.
IMO, you can not measure Ug on a radiograph using a scale. as the Ug will always be very negligible in dimension, usually less than 0.5 mm (if proper techniques are followed)
You can measure the Ug (the penumbra), only if you are making a 'deliberate' setup like large Object to film distance, large source size than the discontinuity size whose Ug is to be measured etc.
And finally, if the Ug is measurable on the film, really it is a bad quality radiograph...!!!
Respectfully,
Nandesh Kumar A
--- On Tue, 30/10/12, Vajjiravelu Ravi <vajjiraveluravi3@gmail.com> wrote:
From: Vajjiravelu Ravi <vajjiraveluravi3@gmail.com>
Subject: Re: [MW:15815] Can we measure the Ug
To: materials-welding@googlegroups.com
Date: Tuesday, 30 October, 2012, 12:24 PM
the question is how it is possible to measure the Ug, anyhow thks for your kind response On Tue, Oct 30, 2012 at 1:33 PM, cbe swamy <cbe_swamym@hotmail.com> wrote: Dear all, T-274.1 Geometric Unsharpness Determination. Geometric unsharpness of the radiograph shall be determined in accordance with: U g = Fd/D where, U g = geometric unsharpness F = source size: the maximum projected dimension of the radiating source (or effective focal spot) in the plane perpendicular to the distance D from the weld or object being radiographed D = distance from source of radiation to weld or object being radiographed d p distance from source side of weld or object being radiographed to the film D and d shall be determined at the approximate center of the area of interest. Please refer Sec -V ASME for more details.
Thank & Best Regards,
M Veera SAMY- Bureau Veritas. Coimbatore -- Vajjiravelu Ravi Welding,Painting,NDT & ISO 9001/2008 take all steps to save our health wealth & environment. -- To post to this group, send email to materials-welding@googlegroups.com To unsubscribe from this group, send email to materials-welding+unsubscribe@googlegroups.com For more options, visit this group's bolg at http://materials-welding.blogspot.com/ http://www.linkedin.com/groups/MaterialsWelding-122787?home=&gid=122787&trk=anet_ug_hm The views expressed/exchnaged in this group are members personel views and meant for educational purposes only, Users must take their own decisions w.r.t. applicable code/standard/contract documents.
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