Incomplete penetration/fusion

Date 03-17-2007 01:36

Hello guys,
I have posted part of this question on the forum before but can't seem to find it anywhere. Hopefully someone can clarify this for me once and for all.
B31.3 Fig.341.3.2 shows typical weld imperfections but the only picture of of a missed edge on the root is one shown with misalignment. If the internal bores of the pipes are aligned and you still have a missed edge is it still incomplete penetration ? If the root has quite clearly penetrated into the pipe but has only fused on one side would that not be lack of fusion and not lack of (or incomplete) penetration ?
As I have mentioned before in the southern hemisphere we call one missed edge "Lack of root fusion" and both edges missed is "Lack of penetration".
If one or both edges are missed it creates a notch (stress raiser) that can easily propogate to a crack.
Normal Fluid Service (Girth & Mitre Groove Welds) allows some incomplete penetration but absolutely zero lack of fusion.Does that mean that 1/4" of lack of fusion inside the weld is more detrimental to the weld than 1.5 inches of incomplete penetration that is exposed to the surface?

While I am on a roll I have another one I hope someone can clarify.
Fig.341.3.2 (a) and (b) show two examples of lack of fusion.
Slag inclusions are usually found between runs or on the side of a run similar to as shown in (a) & (b) so in the majority of cases when you have a slag inclusion you have lack of fusion. One is allowed and the other is not.
The only time you do not have it is when the inclusion is inside the actual bead.With radiography how can you tell if the slag inclusion is inside the bead (acceptable) or underneath the bead (which is lack of fusion) that is not acceptable ?
Hopefully someone can explain the methodology behind this or point me in the right direction for information.
Thanks and regards,
Shane

By Stephan (***)

Date 03-17-2007 14:42

Hello Shane,

this sounds very very interesting!

I hope I'm having the permission to ask a question?

You are mentioning some specifics or standards(?) "B31.3 Fig.341.2". These are unknown for me - I beg your pardon.

Is it possible to have a look into these standards anywhere?

Thank you and regards,
Stephan

By CWI555

Date 03-17-2007 17:29 Edited 03-17-2007 17:33

Shane,

It just happens that I've recently had to give an answer on your first question to my client. For a case such as that, you have to show what it is, and more importantly what it isn't. In B31.3:
"300.2 Definitions
Some of the terms relating to piping are defined below.
For welding, brazing, and soldering terms not shown
here, definitions in accordance with AWS Standard A3.0 (note 3)
apply.

*The key statement there is "For welding, brazing, and soldering terms not shown
here", definitions in accordance with AWS Standard A3.0 (note 3)
apply." Therefore if it is depicted or otherwise shown in B31.3 that is the definition you go by. If it is not, then you go by AWS 3.0. *

Figure 341.3.4 (C) and (D) depict ASME 31.3 definition of lack of penetration. However; by contrast AWS 3.0 figure 29 (B) would call the 31.3 definition Lack of fusion and in AWS 3.0 figure 26 (J) both faces are unfused and is depicted as AWS definition of lack of penetration.

Therefore a specific departure from the AWS definition is clear as I refer you back to **

As for if it's more or less detrimental, I stay away from the engineering side. As an inspector, the code is many times the only thing covering my ass so I don't stray from it if I can help it. On a personnel note I agree with your concern, but the code is the code.

Now on to your second question:
B31.3 slag inclusion: nonmetallic solid material entrapped in
weld metal or between weld metal and base metal.

A3.0 incomplete fusion (IF). A weld discontinuity in which
fusion did not occur between weld metal and fusion
faces or adjoining weld beads.

By definition, any non occurrence of fusion is IF. So technically your correct in that the slag is a non fusion.
However; the code differentiates the two as noted above. Again, I don't agree with this, but I didn't write the code.
Therefore if it meets the definition of slag inclusion, and does not exceed the specified size for rejection, and has no other associated indications it's acceptable regardless of what I think of it personally.

I have seen associated crack tails and clear cut lack of fusion associated with the slag, in which case I will interprete for that as well.

As for the third part of your post:

To my knowledge, there is no method for determining if the slag is under the bead or not with RT. You can take profile shots, and many other things to assess the location and depth but thats about it.

Slag is slag regardless of it's location by B31.3 standards, and unless you can prove something else is there, has to be judged by the slag criteria in accordance with B31.3.

Hope this helps you.

Regards,
Gerald

By Shane Feder (****)

Date 03-18-2007 19:44

Gerald,
Thank you very much for your response,
Regards,
Shane