Notes and Tips to Welder 4

[jmen68]

I plan to be giving a brief talk during an AWS - Welders Night Out about topics we engineers think about when designing welds. Not calculations but some "whys and other things related". If you all wouldn't mind letting me know from your experiences what are some things you would or possibly should have communicated to welders building your designs over time.
Some of the things I plan on talking about are; over welding how it is costly and not necessary a stronger connection and how welding restraints can introducing stress. I am extremely interested in hearing about your topics if you wish to share. Thanks.

 

[oldestguy]

I suppose you are covering fatigue. When in the Navy back in 1950's serving on an LST (Landing Ship Tank) I noted the welders had specific rules as to length of weld and wait time between each section, etc. The LST was a long slender thing and during storms, looking from stem to stern, one could see it bend up and down with a "displacement" total of maybe a foot, flexing like a long hot dog. They were known to break in half. Ours had "reinforcements" on each main crosswise seam with a "patch" having a zig zag pattern for its welds,lengthening them some.

 

[trustthemodel]

I never spoke directly with the welders but one thing that had come up in conversations with steel fabricators was welding to provide ductility at simple shear connections. (welds at welded seat connections or welded double angle connections for example)

The general feeling I got from the shop guys was that they thought more weld = better connection, however, some design assumptions for the connections include flexibility at the connection which would mean less welding.

 

[KootK]

There was a time when I gave technical presentations for a living and I picked up a useful trick along the way. There is a sweet spot in terms of technical content where audience engagement and overall satisfaction will be maximized. And it is here:

Above most peoples heads but not far above.

Everybody wants to feel that they've learned some nifty new tricks that will make them better and have them feeling that their time and money well spent. At the same time, in the this context, you won't be able to overshoot the average audience members understanding level too far before it just becomes meaningless and frustrating for them. So take care not to humble folks but do no shy away from the "why's" completely in favor of the "what's" just because you'll be presenting to non-engineers. Everybody loves the why's so long as their able to grasp them. Find me a trades person anywhere who doesn't enjoy feeling as though she's got the jump on the engineers that she works with...

If it were me, I'd google the snot out of welding tips by Omer Blodgett and Duane Miller, both of Lincoln Arc Welding. Those guys have been very prolific the space that is "avoidance of common welding problems by way of knowing the fundamentals". Take that info, simplify it a bit (no Mohr's circle etc), and you're off to the races. A couple of examples:

Link
Link

These guys used to have a website with all kinds of great info of this sort but I'm at a loss to find it now...

 

[dold]

Not much to add, but something I see a lot on details in my office:
Try to limit the amount of heat you put into embed plates (in tilt walls and CIP concrete). The plates will expand and spall off concrete around the perimeter of the embeds. So unless you absolutely need 1/4" all around fillet weld, spec something more reasonable. Your bar joist does not have a 100kip reaction, typically...

 

[Ron]

Talk about the defects that are common in welding and how they affect the strength/performance of the weld. Include things like undercut, porosity, lack of fusion, profile, lack of penetration, etc. All of those affect our designs. It is important to point out that the first line of quality control is with the welder....remove the slag, look at the weld, correct as necessary!


A Great Place For Engineers to Help Engineers

Follow me there.....

 

[BUGGAR]

I always tell about the new engineer sent out into the field to "observe" the welding. When he saw a questionable weld, he was told to follow AWS Requirements for Welding Procedure Specifications (WPS), and to stand by the weld and call out "WOOOOPS" real loud until the welding inspector could come by and check the weld procedure.

 

[jmen68]

Thanks everyone for your input, I'll try and do you all proud!

 

[dhengr]

Jmen68:
Be particularly careful at the starts and stops (terminations) of short fillet welds, do not leave any craters, lack of fusion, lack of penetration, etc. Those are stress raisers at a location on the weld which is usually highly stressed, multiaxially. Undercuts and arc strikes which are not cleaned up and filled are stress raisers also. Be careful of welding around vert. standing corners on pls. and members, this often leaves a nick in the pl. (edge/corner) above the upper toe, and is a stress raiser. Do not weld into corners, particularly from multiple directions, stop short of the corner. The normal stresses and the welding residual stresses are really a problem when you weld into a corner. Over welding is as often the fault of the guy who designed and called out the weld size. Look at the number of instances where the go-to detail is a full pen. groove weld whether it is need or not. Too many engineers seem to think their fillet welds should be the same size as the ”k” radii on large rolled steel sections, seldom needed. Be careful with welds which are right near the size boundary btwn. single pass and multi-pass welds. Welders don’t like being called back for undersized welds, so they are inclined to add that extra pass when its not really needed. Always ask yourself, can the guy actually get in there with a gun to make that weld. Does he have convenient, visible access?

 

[oldestguy]

One more from OG. In my home shop welding (and I've done one heck of a lot of arc and gas welding) one problem with different equipment was having difficulty seeing what goes on. A "safe" shade sometimes was too dark and the work suffered accordingly.