American Welding Society Forum
Hi Guys... And Brent Particularly:
The K-area presentation at the inspection seminar last week offered quite a lot of detail about welding inspection in the K-area and highlighted that when welding was done in this area that visual inspection had a 48 hour hold point.
I see the hold point clearly in the 341 Seismic provisions, but not in AISC 360, which it appears only calls for inspection of the area post weld, but no 48 hour hold point time.
The impression I got at the presentation was that ALL hot roll shapes had the 48 hour hold point for inspection without exception. I know I'm not the only one who walked away from that seminar with that.
Is there something important that I missed?
Or is the 48 hour hold point strictly for seismic application ?
It makes a HUGE difference
AISC 341-16 Seismic Provisions for Structural Steel Buildings (2016) Table J6.1 Visual inspection tasks after welding *Footnote:
"When welding of doubler plates, continuity plates or stiffeners has been performed in the k-area, visually
inspect the web k-area for cracks within 3 in. (75 mm) of the weld. The visual inspection shall be performed no
sooner than 48 hours following completion of the welding."
AISC 360 2016 Specification for Structural Steel Buildings Table N5.4-3 Footnote
1 When welding of doubler plates, continuity plates or stiffeners has been performed in the k-area, visually
inspect the web k-area for cracks within 3 in. (75 mm) of the weld.
Good Day Lawrence, again, nice to meet face to face. Too bad we couldn't sit down for dinner or something while there. They had me going all the time.
As 360 is for standard D1.1 types construction and Chapter N deals with pre, during, and post fabrication inspections of non-seismic work being performed, the line item for k-area inspection, and especially because of the note, is not referring in that case to seismic applications. As it includes welding that would also normally be in the k-area it also includes stiffener plates and does not specify which corner clip is considered.
As Duane noted during a comment he made, doesn't matter, stay out of the k-area or do the inspection. The rotary straightening is performed specifically on mid to light W-shapes and creates the hazard conditions in the k-area. The only way to avoid this is to use the larger corner clips at ALL stiffeners and continuity plates.
Now, continuity plates normally are Demand Critical and seismic related so they are going to be in 341 and D1.8 as well. But not the case with stiffener plates.
Have a Great Day, Brent
So stiffeners welded in the K-area under AISC 360 & D1.1 don't require a 48 hour hold point for visual inspection. They simply need inspection.
Do I have that right ?
I think one must consider the base metal specification as well. D1.1, clause 6.11 includes a hold time (48 hrs.) for NDE on certain Q&T steels or those with high yield strength that may be more sensitive to delayed cold cracking. I would think that applies to the k-area as well.
Thankfully my little world is filled only with Group I & II base metals for the most part. And A607 which for the life of me I don't know why it's not a prequalified base metal. :/
I told you I would be back...just like a bad penny but nothing like Arnold.
Lawrence, I think I am going to have to back down a bit. I can't find any reference to support my statement to HOLD for 48 hrs even for k-area welds per 360 Chapter N. It is only for a VT and does not specify a hold time.
The only thing I would get picky about here is the D1.1 and ALL other references that indicate that VT, MT, and UT are not to be performed until member is down to ambient temps. I can easily make them hold that long and at least give it some time for any cracking to occur.
Because D1.1 and AISC 360 are dealing with lighter materials, no demand critical welds, generally fillet welds, (I believe we somewhat covered some of this with a question from the floor) and the welds with even D1.1/360 corner clips with holdbacks should be low enough in restraint to not cause major concern for cracking.
My contention is that if the k-area is a concern at one point then it is at all points because it will always have notch toughness issues and be prone to hydrogen cracking. We know that modern mill practices are far better than they used to be and control of mechanical properties is better along with changes in chemical/alloy additions. This is why we have totally moved away from A36 steels for W-shapes and even A572-50 and are now into the tight controls of A992. Far superior qualities for columns and beams.
Anyway, you are correct that per AISC 360 there is no 48 hr hold for k-area welding. Only in the Seismic codes of D1.8 and 341/358.
Have a Great Day, Brent
Thanks for the response Brent!
We walked out of that seminar worried that we might have had a very big problem.
As far as "mill practices" I think lighter and stronger (whatever strong means) is usually what they go after, with weldability coming in 3rd. :)
To add to the complication.. We have a number of customers who still demand seal welding on HDG and some epoxy painted HR. This presents some other inspection issues. Most folks don't demand seal welding on the type of stuff we do, but some are just old school or have very specific concerns about corrosive environments and moisture making the steel less pretty.
Miller speaks well on that part of it here http://www.jflf.org/v/vspfiles/assets/pdf/design_file6.pdf
In the end... I guess we were forced to dig deeper into our subjects, which is always good.
"We know that modern mill practices are far better than they used to be" - Brent
I don't know about that, maybe chemical and mechanical, but dimensional is wildly different than back in the day. It's nothing to see beam flanges that are not centered over the web, or different flange thicknesses from one side of the web to the other. Flange tilt and such is somewhat better, but the dimensional aspects are something else.
Just noticed something. Let me get my books out, they are still packed. But, look also at Commentary for A3.1c and J10.8 along with Commentary of the N tables.
Now, I was positive I had a reference to a 48 hr hold for this. It definitely is NOT in D1.1. Give me some time to get unpacked and find my AISC 360 and go back over the Commentary in particular. They give some good insight into the k-area that you normally don't find until you get into the AISC and AWS Seismic codes.
The bottom line is, the potential cracking in the k-area is prone to happen up to and even after 48 hrs. So, why would you not look at it as much after the fabrication as possible within reason. About 48 hrs.
I will return.
Fig J10.7 shows a detail with the K-area being avoided and a 1 weld leg length "hold back" as a suggestion. But again it appears to be just that .. A suggestion.
Just trying to define the letter of the law from best practice recommendations.
Knowing about compliance is the first step.
As an aside... C-channel also goes through rotary straightening processes... But I don't see much addressing what would be the K-area there at all.
So does tubing.
K-areas exist for angle, channel, and W-shapes. Only the ones in W-shapes are of concern because of the loading and specs.
I am still trying to get caught up on some issues in the office and get ready to leave for work in a while but should be able to get into this sometime this evening.
For the non-seismic construction, are you talking about (ASTM A6) Group 4 and 5 materials? These heavy shapes need special care when cutting access holes, preheat of 150°F is required and then MT or PT in the "K" areas (around access holes) and thermally cut edges to make sure they are crack free prior to welding. AWS D1.1:2015 Clause 5.16.3 and Fig. 5.2.
Just wondering John, what are these Group 4 & 5 materials you refer to? .....
You do know those designations have not been in ASTM or AISC 360 for about 15 years??
LOL....showing my age?
Which age is that John?? The Ice Age?...LOL
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