AWS 5.17 about Welding Access Hole 1

[benny80]

Hello, guys, I am a Graduate engineer based in the UK and currently working in China for one power project. The problem I am facing now is about "Welding Access Hole" at Fillet Welded Shape component as shown in Figure 5.2 on AWS. According to AWS 5.17, "Fillet welds shall not be returned through weld access holes", which I take the concerns are about causing cracks probably(correct me if I am wrong here). But the current circumstance in my case is "returned-fillet welds through the access hole" will be more reliable in terms of less possibility of causing cracks. Due to the short of knowledge and experience, I could not find any standard or code supporting this procedure. Any direction or suggestion from you guys will be highly appreciated. Many thanks.

 

[HgTX]

I'm not really understanding the question. Is the issue that the welds have already been returned through the holes and you're wondering if it's worse to leave them in place or remediate?

Hg

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[benny80]

Thanks, Hg.
Do apologise for confusion caused in my post. Actually only small number pieces have been done with returned welds through the holes but I am wondering will procedure be allowed in reality, even against some rules from .

Benny

 

[gtaw]

Check your welding specifications. I don't believe you really mean A5.17, that's a filler metal specification.

Did you mean to list D1.1 Structural Welding Code/Steel perhaps?



Best regards - Al

 

[benny1980]

Many thanks, Gtaw
Yes, you are right, the question is from AWS D1.1 for Structural Welding Code - Steel, chapter 5.17 for the welding access hole.

Regards

 

[gtaw]

The issue of wrapping the weld around the corners of the access hole through the web results in undercut (called corner melt by some welding standards). The localized undercut acts as notched stress riser. Like any notched stress riser, it acts as crack initiator.

The bridge welding code requires the weld in the area of the access hole to be a complete joint penetration groove weld to minimize the stress riser.

Best regards - Al

 

[HgTX]

Where are you seeing in the bridge code the requirement for the weld in the area of the access hole to be CJP?

As far as I know, running the web-to-flange fillet welds out onto a runoff tab and then putting in the access hole afterward with no further welding is in accordance with code--and it's standard practice for Texas, which probably does more of these than any other DOT.

If one does the welding after the hole is put in, one needs to balance the questions of potential undercut with the wrapped weld, the poor fatigue detail of the transverse portion of the weld, the lack of seal if the welds are not wrapped, and the potential undercut if the welds are run all the way out to the edge of the hole, not wrapped, but not held back sufficiently.

AWS D1.1 and the AISC steel design manual have some recommended details for welding access holes. Benny, if you think your particular case is such that the non-recommended detail will be better than the recommended detail, only you (or your design engineer, if that is not you) can make that judgement. The codes list what is commonly a better detail, for most applications.

Hg

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[benny1980]

gtaw,
Do appreciate the comments provided from you. I shall go for a check with the standards for bridge welding.

Hgtx,
I am not in charge of the design yet (hopefull someday soon), but I could fully understand what you mean about the problem and the way to account AWS in real design work. Thanks a lot for your direction.

Regards,
Benny

 

[HgTX]

Bridge code is woefully silent on weld access holes, other than finish requirements. Every once in a while there is vague discussion of adding such details to the bridge code, but at the moment there's nothing much there. If you're not doing a bridge, stick to AWS D1.1 and the AISC manual, which both have considerable detail for the access holes. D1.1 has provisions for cyclically loaded structures, if that's what yours is. D1.8 (the seismic code; applicable to structures designed to the AISC seismic provisions) has a handful of additional requirements for access holes for "demand critical" welds.

I was involved recently with a bridge where the fabricator put in access holes where the designer had not called for them (a question of fabrication sequence) and the designer decided that it was better from a fatigue standpoint to hold the welds back 1/4" (5-6 mm) from the edge of the hole than to wrap the welds around the hole, but also better to leave the welds wrapped where the fabricator had already done them than to go grinding them out. But that was a very specific situation. Yours will be different. (For starters, it's not a highway bridge under truck loading.)

Hg

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