Interpretation of Radiographs UW-51/UW-52?

[WBH]

Interpretation of indications revealed by RT UW-52/UW-51
Example: 3/8" thick ss material radiographed to RT-4

1.0 Junction of girth seam and long. seam radiographed Per UW 11(a)(5)(b): shall meet the minimum requirements for spot radiograph UW-52

2.0 UW -52 slag inclusions/elongated indications greater than 2/3t are rejectable; in the example above maximum allowable indication would be 1/8" in length.

3.0 If this radiograph were to be evaluated to UW-51, the maximum allowable elongated indication would be 1/4" (in materials up to 3/4" in thickness).

Could this radiograph be evaluated to UW-51, as this would exceed the minimum requirements of UW-52 as stated in 1.0 above?

My interpretation is no, UW-52 would be correct without exception. This has come up in the past with fabrication shops, with the radiographed rejected based upon UW-52 but only with some resistance from the fabrication shop. These vessels were designed for RT-4 and could not pass UW-52, how could UW-51 be applicable? In addition if you evaluate to UW-51 then rounded indications would be a factor in seam welds and nozzles greater than 10" NPS etc... If evaluated to UW-51 but radiographed to UW-52 what do you stamp on the ASME nameplate?

Appreciate your input on this matter.
WBH

 

[qualityManager]

If I am understanding your series of questions correctly, I agree with your conclusion that UW-51 may not be used to satisfy the spot radiography requirement of UW-11(a)(5)(b).

However, I would take the "...as a minimum..." part of the sentance in UW-11(a)(5)(b) to mean that you may do a full RT to the seam per UW-51 and still stamp RT2 or RT4.

I don't know why you would want to though... unless you were building a RT1 vessel anyway the point would be moot...

Cheers,
WRW

 

[bmoorthy]

As per your statement (2)
2/3 of t is aceptable, in which case 2/3 of 3/8" is 1/4". I think there is no conflict amongst the clauses mentioned (Atleast in those which you have mentioned).