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:
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"
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.
Thanks in Advance!
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.
> 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.
Just on the off chance that this is not a troll.
The free answer is "It depends".
Documentation, to be valid, is situation specific, requires an Engineer's
stamp and is very seldom free.
Good luck, YMMV
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
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
To proceed without the proper consultations and/or approvals would be
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
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.
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
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
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. :-)