Friday, October 7, 2011

Questions on B31.3


I would really appreciate some of your time and expertise. I have some B31.3 questions.

1. Is the % of RT that is required generally understood as a quantity of welds (verses linear)? 341.4.1(a)(1)

PWC:  This paragraph:
341.4.1, b) Other Examination (1) Not less than 5% of circumferential butt and miter groove welds shall be examined fully by random radiography…”
The words, “shall be examined fully”, would indicate to me that the percentage is of complete welds, not linear inches/feet of weld.

2. If I RT 5% of fabrication (150 welds in this case) with each welder being represented and I have 10 welders, do I exceed the minimum?

PWC:  I’m trying to better understand your question…
If 150 welds are equal to 5% of your fabrication, and 9 of those Welders each welded one of those joints and 1 of your Welders welded the remaining 141 joints, you’ve met your minimum.
If 150 welds is the total number of welds in this fabrication then 8 of those welds require RT, but if 10 Welders worked the project you will need to RT an additional 2 welds (one for each Welder).

3. For “Normal Fluid Service”, am I required to have 5% of fabrication RT if I have 100% visual (by CWI)? 341.4.1(a)(1) last sentence

PWC:  Under Qualifications of the inspector is this line…
340.4 (b) The owner’s Inspector shall have not less than 10 years experience…”
I can be a CWI with 5 years experience and I would not meet the requirements of 340.4 (b).

4. In “Cat M” I am required to have “all fabrication” visually examined M341.4(a)(1). Does that exclude the 20% random RT M341.4(b)(1), or is that required regardless of the 100% visual? M341.4(b)(2) refers to 341.4.1(b)(1)

PWC:  The first requirement of any NDE is that the weld meet the visual acceptance requirement, so yes, it would include the RT’d joints.

Tim C:  I am a CWI in the field for a construction / fabrication company. The reason for asking these specific questions is that, per another CWI in the company, we have been doing 100% visual, and 5% RT of *each* welder. This (5% of each) is getting expensive, especially when we hire more welders to get the job done quicker. I am satisfying the 100% visual examination and hydro or pneumatic testing (as another suitable NDT method). Plus, providing weld mapping and MTR’s. I think we have our bases covered. I would like to help cut costs. But more importantly, I want to make sure I am interpreting the code correctly.

Thank you,
Tim Crowder, CWI
Lafayette, IN

PWC:  Tim, if I read your question correctly it would appear to me that you could cut cost by RT’ing 5% of the welds, not 5% of each Welders welds and still meet your minimum requirement.