What revision are you looking at?
Interesting issue. I saw a similar situation with the old MIL-STD-278. If my memory has not failed once again, the acceptance criteria in for that standard did not address porosity. If porosity was a concern, the drawing had to specify penetrant testing in order to kick the user into PT acceptance criteria for porosity. Porosity was not even listed in the acceptance criteria for VT.
We may have had a similar situation will D1.2. Porosity is such a prevalent issue when welding aluminum that the committee may have felt that the part or weldment had to be critical enough to warrant NDT other than just VT before porosity was considered a serious concern. Under D1.2 we're addressing structures, not tanks or systems where "leakage" is an issue.
Unless the porosity reaches a magnitude where there is a substantial loss of section, who cares? Consider the sheet metal code that allow(ed) porosity up to 3/16 inch in diameter. Sheet metal, porosity, no big deal.
Best regards - Al
Al, that is a good point, and one that I never really thought about. Having a specific NDT performed would cover it, if needed. It just seems odd that there isn't at least some kind of visual criteria. Once again, I appreciate your input and expertise.
LOL and LOL
I was looking at my copy of 2008.
And I went back to 2003 and could not find a peep about porosity in VT, not even in commentary.
As you know, I build large tubular structures that must withstand all sorts of abuse by airmen in every branch of the service. I can't afford to play around with my welding processes. I still preach to my welders and my inspectors that porosity found in a VT will be written up as a defect. If I give 'em an inch, next thing I'll see is Swiss cheese in every joint!
I won't argue against your logic because I agree with your position. The code sets the minimum standards not the optimum requirements.
Best regards - Al
Actually, looking at an old WPS (qualified long before I started here), the RT criteria is what is listed for visual surface porosity. So someone had something like an idea of what to look for.
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