Maximun size of acceptable porosity

[Joss10]

Here below is the Visual Inspection Acceptance Criteria as per AWS D1.1 for Statically loaded non tubular connections (Table 6.1)

(8) Porosity
(A) CJP groove welds in butt joints transverse to the direction of computed tensile stress
shall have no visible piping porosity. For all other groove welds and for fillet welds, the
sum of the visible piping porosity 1/32 in [1 mm] or greater in diameter shall not exceed
3/8 in [10 mm] in any linear inch of weld and shall not exceed 3/4 in [20 mm] in any
12 in [300 mm] length of weld

Questions:
For fillet welds which should be the maximun diameter of piping porosity?
Always talking about "piping porosity" , there is not other kind of porosity to be evaluated?

Any input will be appreciated.

 

[gtaw]

The porosity limitations apply to both grooves and fillet welds unless the provision states it applies to groove welds only.

Piping porosity is the only porosity of concern because it substantially reduces the cross section of the weld. Look in the back of AWS D1.1 in the commentary. It will provide additional insight. Look in the commentary under the same clause number as in the body of th code. in this case you will be looking at clause 6.

Best regards - Al

 

[Joss10]

gtaw,
Thanks for your input but again :

Which should be the maximiun aceptable diameter of piping porosity??

Statement is saying piping porosity 1 mm or greater in diameter shall not exceed 10 mm in any linear inch of weld..., so having

two piping porosity 4 mm and one 2 mm might be considered acceptable??

 

[gtaw]

Exactly, there are two conditions to consider: is the connection subject to static or cyclic loading? You specified a static load. You now have to consider the weld type; groove or fillet. You specified a fillet weld. That being the case, static loaded fillet welds, the criteria is:
a) There is no limits imposed on porosity that is less than 1 mm in diameter. You can have 20 pores if none are more than 1 mm in diameter. This sound crazy because if you have 30 pores, each measuring 0.5 mm, they would sum up to 15 mm in a weld 25mm long! No problem, the weld is acceptable.
b) The sum of all porosity measuring 1 mm or larger is limited to 10 mm in any 25.4 in of weld. Now, because the pores are 1 mm or larger, they must be summed. You can have 10 pores, each measuring exactly 1 mm in diameter in any 20 mm length of weld and the weld is still fine.
c) The sum of all porosity 1 mm or larger cannot exceed 20 mm in any continuous 300 mm of length. So, if the pore holes are separated so condition "b" is satisfied, one must still consider the number and the sum of their diameters in any 300 mm of length of weld. What to do if the continuous weld is only 150 inches in length? I prorate the sum. In the case of 150 mm of weld length, I use a sum of 10 mm as the maximum in the full 150 mm length of weld. There are others that would argue only condition "b" must be satisfied if the weld is less than 300 mm in length.

Best regards - Al

 

[Joss10]

gtaw,
Following your statement in point b)
Any sum of porosity diameter < 10 mm. in any 25.4 mm of weld should be acceptable.
Conclusion : two pores 5 mm diameter are acceptables or even one pore 9.5 mm is acceptable.
Is it right ???