B31.3 Lack of penetration or fusion ?

Date 09-03-2008 01:51 Edited 09-03-2008 01:59

Hello guys,
I first posted a similar topic back at the beginning of '07 and I need assistance again please.
Gerald gave me an excellent response but I need to take it further.

http://www.aws.org/cgi-bin/mwf/topic_show.pl?pid=58162;hl=

As explained in my earlier post I am still confused with the difference between lack of root fusion and lack of root penetration.

For branch connections I have always believed that you must have complete root fusion/penetration??? (both edges of root fused) but now I am not so sure.
B31.3 Fig 328.4.4 shows that the hole for a branch connection can be up to 1/8" smaller (each side)than the internal bore of the branch connection.
If you take Fig 341.3.2 (c) and substitute a single bevel weld for the single vee weld shown and turn it 90 degrees you would have a similar joint configuration to the branch connection. You would then presumably have misalignment of the bore.
If you failed to fuse the bottom edge of the run pipe would that then be classed as "Incomplete penetration due to internal misalignment." If so you are allowed 1.5 " of incomplete penetration as per 341.3.2.
Similarly you could have no internal misalignment but still fail to fuse both edges and then it would be classed as "Incomplete penetration of Weld Groove.". Again, 1.5 " acceptable.
As you are all probably well aware it is quite easy to miss one edge of the root (without misalignment) if the welder has poor technique but I cannot find a picture of this in either B31.3 or AWS 3.0.
Both documents show Lack of Sidewall Fusion and Lack of fusion between adjacent passes (interrun) but not Lack of fusion at the root.

Any assistance would be greatly appreciated.
Regards,
Shane

By dbigkahunna (****)

Date 09-03-2008 02:15

IP is where the rood did not penetrate into the grove. The land will be clearly noticeable. LF is where the bead did not break down the land but there is weld along the root. I have seen LF called on pipe beads with SMAW. I have to call bunk. LF on the beat generaly is limited to GMAW. LF in SMAW can bee seen on LH welds in fill and cap. I have seen two instances where LF was called on the bead where it was really LF. These were on open root 7018 and I called bunk and had the welds cut out and sure enough, there it was. BUt using XX10 for the bead and HP you may have IP but not LF.
BABRt's

By Shane Feder (****)

Date 09-03-2008 03:00

dbigkahunna,
Thanks for your response but I think we are looking at things a bit differently. (I realise you are predominantly pipelining so API 1104 is your code whereas my problem is with B31.3)
API 1104 Figure 16 shows a diagram of Incomplete Fusion at Root of Bead (IF) and Clause 9.3.4 allows up to 1" maximum length.
API 1104 Figure 13 shows a diagram of Inadequate Penetration without Hi-Lo (IP) and Clause 9.3.1 again allows up to 1" maximum length.

Perfectly clear, diagrams clearly show different defects and acceptable length is clearly noted.

Now we come to B31.3.
There is nothing similar to Incomplete Fusion at Root Bead in B31.3.
There is nothing in AWS A3.0 that shows a similar defect to Incomplete Fusion at Root Bead.
In the Southern Hemisphere we call one edge missed - Lack of Root Fusion / two edges missed - Lack of Penetration.
However, if we are working to B31.3 NFS Lack of Root Fusion is not allowed while 1.5" of Lack of Root Penetration is allowed
A huge amount of root runs in refineries are done with GTAW and it is a lot easier to miss an edge or edges with GTAW than it is with 6010s.
It is just very confusing (I think I will grab a beer and worry about it tomorrow)
Regards,
Shane

By 803056

Date 09-03-2008 13:44 Edited 09-03-2008 13:51

Hello Shane;

Maybe the two attached sketches will help clarify the situation.

You can have complete joint penetration where the weld projects into the root area without fusing to one or both members in the area of the root. The unacceptable condition is incomplete fusion (lack of fusion to the non-AWS world).

You can have incomplete joint penetration where the weld metal does not project through to the root of the joint, i.e., no weld metal is fused to either member in the root and the weld fails to project into the root, i.e. beyond what would be the root surface. The unacceptable condition is incomplete joint penetration (lack of penetration to the non-AWS world).

At least, this is the way I understand the two discontinuities to be described. In AWS 3.0-2001, figure 29 shows incomplete fusion. Figure 26 depicts incomplete joint penetration. I think my sketches depicts how the definitions could apply to branch fittings.

I hope the sketches are helpful.

Best regards - Al

Attachment: BranchFittingDefectIncomFusion3-Sept-08.wmf (299k)

Attachment: BranchFittingDefectIncomPen3-Sept-08.wmf (38k)

By Shane Feder (****)

Date 09-03-2008 20:07

Al,
Thanks for the diagrams and response.
Unfortunately it doesn't help me as we are both agreeing on what is incomplete fusion of the root and what is incomplete penetration of the root but it appears it is not addressed by the code.
The way I am interpreting it is for B31.3 NFS you are not allowed incomplete fusion (one missed edge) but you can have 1.5" of incomplete penetration (two missed edges) ?????
Fig 341.3.2 (c) shows one missed edge but that is classed as "Incomplete Penetration due to Internal Misalignment." What is that condition classed as if there is no internal misalignment ?
Figure 29 in AWS A3.0 only depicts Lack of Sidewall and Lack of Interrun Fusion, it does not show Lack of fusion at the root.
API 1104 addresses the issue quite clearly with diagrams depicting Inadequate Penetration with Hi-Lo, Inadequate Penetration without Hi-Lo and Incomplete Fusion at Root of Bead.
How can I reject / accept welds when I cannot be sure whether B31.3 deems them to be acceptable or rejectable.
Regards,
Shane

By 803056

Date 09-03-2008 20:18

Some codes are well written and some are not. Each takes a different view of what they believe to be unacceptable discontinuities. If the code doesn't address the condition, the inspector can't use the condition as a reason to reject the weld.

A good example of this is ASME Section VIII. It doesn't address undercut. The word doesn't appear in relation to welding. They do however talk about "material thinning due to the manufacturing process (undercut in my way of thinking) so I don't reject any U stamped vessel for excessive undercut. Material thinning, yes, undercut, no.

The old visual acceptance criteria used by the Navy didn't address porosity. If porosity was to be evaluated, PT had to be performed. Do I agree with the old standard? No, but that's what I had to work with and it was my job to use the criteria that was provided.

Best regards - Al

By 3.2 Inspector (***)

Date 09-08-2008 09:18

Interesting, interesting indeed.

I will make a cop a coffee and open a new pack of cigarretes, wipe the dust off B31.3 and take a look :)
I really dont mean to bring wood to a fire which has been out for some time.

But how do you determine if there is lack of interrun fusion in a branch weld?
I was told in a previous post that RT is not required on branch welds - even though its stated in table 341.3.2 as being an acceptable method of examination.

Could it be that figure 341.3.2 (c) just is badly worded and not intended to exclude similar defect with perfect alignment?

As explained in my earlier post I am still confused with the difference between lack of root fusion and lack of root penetration......You can penetrate the root without having fusion of the edges.

3.2

This post is not intended to stir up anything, but simply to learn.

By dbigkahunna (****)

Date 09-08-2008 15:34

ASME
Always
Sometimes
Maybe
Except
BABRt's

By 3.2 Inspector (***)

Date 09-08-2008 15:35

That is a big 10-4