Dear Adeel,
The key to understanding interpretation given in any code is to read line by line carefully and repeatedly.
So I will try to explain with an example,
(b) Rule (1). Say I have a 12 mm (t) thick plate and i'm finding a 2.8 mm dia rounded indication on weld joint.
As per code, the maximum permissible dimension for rounded dimension shall be 12 % of t [which in our case is 20% of 12mm = 2.4 mm ] or 3 mm which ever is smaller. So our base criteria is 2.4 mm.
In our case, we have a 2.8 mm dia indication which is greater than 2.4 mm as per code, hence the weld joint has failed to clear Radio graphic testing.
----> Second rule is for weldments which contain more than 1 no of rounded indications.
It is further subdivided for weldment size less than 3 mm
(b) Rule (2) Say i have a 2.8 mm (t) plate which contains a 15 no's of rounded indications of diameter 0.4 mm. Length of test piece is 150 mm
As per code, firstly we have to see whether the rounded indications of diameter 0.4 is acceptable or not. As per Rule 1, the rounded indication is acceptable.
Secondly, code says the maximum no of acceptable rounded indication is 12 no's in 150 mm length of weld. In our case, we have 15 no's which is clearly more than 12 no's as specified in code. So even thought the size of the indication is acceptable, the no's are greater than specification so the weld joint has failed to clear RT.
In case if our weld length is less than 150 mm , then the no of acceptable indications also lessens accordingly. The exact no is not mentioned in code.
(b) Rule (3) This rule is applicable for plate thickness of 3 mm and greater than 3 mm. You can refer to the figure mentioned for acceptable limits. Special case is if the diameter of the rounded indication is lesser than 0.8 mm, then it shall not be considered for evaluation in acceptance criteria for the thickness of plate specified as greater than 3 mm
Regards,
Bala Guru Nathan C.
On Tuesday, August 7, 2018 at 2:10:27 PM UTC+5:30, adeel wrote:
Please anyone can explain me the paraghraph in easy words about radiography testing for welder or welding operator qualification ...please read the paragraph in image and explain me in easy words ... Reference .... Qw 191.2.2
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