Since I'm the company geek, the boss has asked me to go online and find the minimum weld spec - presumably, how _little_ fillet he can get away with, in these two cases:
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That is, both for fillet on one side and fillet on both sides, no weld prep, just the 3/4" sheet butted up against the flat side of the 1 1/2" plate.
And he says, "I want documentation."
Like I said, I'm only the company geek, so I need your expertise here.
A callout from some "official" book would be really welcome, as well.
Seems like you need to give a few more details: eg, forces the structure is expected to survive and rough overall dimensions. Will forces pull the assembly apart, or push it together? Also the purpose of assembly -- surface decorations needing tack welds vs earth-moving equipment, or life safety equipment vs a picture frame.
The AISC Manual of Steel Construction has the specs and drawings for welded joints, but it doesn't give simple executive-summary answers, you have to know what you're doing.
I can tell ya, from my experience in welding much lighter steel components, that it's often a bad idea to try to weld one side only, when the components in the fabrication require a fillet to join them.
The amount of distortion that will take place during the cooling phase will likely be very significant.. the 3/4" member will lean to the side of the single fillet.
If the boss doesn't fully understand metal fabrications by welding, particularly in these thicknesses, he would be wise to turn this job over to someone who does, such as a structural engineer and a qualified and experienced welder.
To proceed without the proper consultations and/or approvals would be negligent.
It's not likely that anyone could give you any specific recommendations of "minimum weld" without more details WRT the expected loads on the components and the use of the assembly.
A link to MIL-STD-1689A since you probably are not working on a submarine....
1689 has looser requirements than 1688. I usually don't get to use 1689 very often- I spend most of my time rump-over-teakettle on subs.
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Please note: Educated and knowledgeable people and companies make their money by answering such questions. You may not find the "documentation" you are looking for without paying for it.
What you can find here would be educated guesses, with lots of disclaimers. Some of the people who participate in this group are extremely knowledgeable, and we are all (hopefully) aware of the hazards of liability.
What is the stress loading like? Tensile? Shear? Rotational against long axis? More info, please.
The only little factoid I could give is that the navy likes to weld plates like that using a full penetration weld. Bevel the thinner member, weld it up to one or two layers under flush, arc out the unwelded side until past the fusion line, weld that side up to just over flush, finish the first side. Recommend you put a fillet on both sides of the plate to ease the stress/strain transfer through the plates. These fillets, reinforcing a full-penny weld, can be smaller in leg length than the thickness of the thinner member.
If the weld boss doesn't want to go full-penny, he should size his fillets according to the size of the smaller member at a minimum. For
3/4" plate, use a pair 3/4" fillets, one on each side. You want to guarantee that your plates fail before your weld does.
I would strongly recommend against a single fillet weld. The stresses imposed by welding would require some skill in pre-setting the plates to compensate for the pulling action of welding. If the members are restrained during welding, such a single fillet also creates huge stresses along the Heat Affected Zone (HAZ) that will increase the chances of it cracking. A single fillet is very significantly weaker than a double fillet, when it comes to resisting stresses on the structure.
I know that wanting to do it as in-expensively as possible is good for business. I also know that having the weld fail can be very, very bad for your business. If this part is a structural member placed under stress/strain and your welder boss only uses a single fillet smaller than the thickness of the thinner member, I would start putting out my resumes to other employers....
Oh, my! Too many answers to thank each of you individually, so thanks to one and all - apparently the answer is "it depends," so I've told the boss that since I'm only a geek, I'm not qualified for this task. Maybe after two years of welding school plus a year of materials engineering, but not today. :-)
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