"The total area, when projected radially through the weld, shall not exceed 2% of the projected weld area in the radiograph. The area shall be the length the weld affected by the porosity (with a minimum length of 150 mm ) times the maximum width of the weld."
The above criterion is in order to evaluate porosity on a radiograph. Now I've a uniformly distributed porosity of upto 45 mm length. The total length of the weld is 192 cm (24 inch OD, pipeline )Can anybody explain me (if possible with a sketch) how to proceed with it?
15:09 Mar-01-2010 Nigel Armstrong Engineering, - Specialist services United Kingdom, Joined Oct 2000 1094
Re: Can anybody explain me for ISO 13847 ?In Reply to Nandesh Kumar A at 14:21 Feb-28-2010 (Opening).
If the weld length affected by porosity is 45mm, this is less than 150mm and so you must use the default 150mm figure. Multiply this by the maximum width of the weld in the affected region and then multiply by 0,02 (2%). Say the weld width is 25mm: 150mm x 25mm x 0,02 = 75 sq mm. Measure and add together all pore diameters in the affected region, multiply the total by pi. If the calcualted figure is less than your previous calculation (75 sq mm in my example) then the area is accpetable. Greater pore area sum total = rejectable.
The use of "projected" radially and weld area is to maintain proportionality with regard to image magnification. If the set-up used has a low ratio between source-to-object distance and material thickness, differential magnification will enlarge a source-side pore more than a film-side pore.
Assuming you used a panoramic exposure on a 24" sch 40 pipe (wt = 0,375") then differential magnification is not a problem you need worry about.
Re: Can anybody explain me for ISO 13847 ?In Reply to Nigel Armstrong at 15:09 Mar-01-2010 .
Sir can you please help me to understand below clause of my project spec.
"The distribution of scattered porosity is such that when projected radially through the weld the total area of porosity exceeds 1% of any 600mm Sq of projected weld metal."
Thanks in advance