Of the professional stud welders availible in my area
they are quite expensive and are not keen on comming to
my remote location.
I have an application where I need to weld 1/2" studs through
20 gauge galvanized steel deck and into open web steel joists
for my own house.
This weld is typically used to join all three (stud, deck, joist)
together, but of course the stud/joist bond is most important
(It resists internal shear of joist when it deflects).
Here's some of the advice I got so far, but I don't know how
good it is.
a) Use a 5/8" hole saw to remove the surrounding deck
beforehand.
b) Remember to grind off the aluminum nipple on the stud first.
c) Test the bond by using a sledge hammer on one of the studs.
If you can bend it 15 degrees without it cracking, the weld
is good.
d) Use a 7018 or 6011 rod.
Any help here would be appreciated.
If it were my own house I'd follow the D1.1 code, which basically states that a 1/2" diameter stud requires a minimum 1/4" fillet weld, (so you would need at least a 1" diameter hole in the decking), and, in using the SMAW process, the rods must be low hydrogen and either 5/32" or 3/16" in diameter for a 1/2" diameter stud. I'd go with at least a 30 degree bend after one stud is welded and allowed to cool, to make sure the weld is good before proceeding, especially if the joists have a thick coat of paint on them, as most painted joists do. If you can, you might want to remove the paint prior to tacking the studs in place. Incidently, I don't know about the stud welding professionals in your area, but some of the guys I've dealt with were not aware that welding through deck studs is not prequalified in D1.1. Hope this helps.
I am curious as to what else the stud will be attached to. I am not familiar with this being used in a house. Just qualify welding thru deck.
Brian J. Maas
I'm using commercial techniques. This is all concrete construction with open web joists supporting suspended concrete floors. The steel deck is laid on top of the joists, the studs are welded vertically thru the deck and into the joists, then the concrete slab is poured. The studs help the
joist resist internal shear when the joist is loaded.
I would really try and get a stud machine if at all possible. It will make your life much easier. Then just do a random ping test on the studs. Are you using reenforcing wire also. Is this a multi-story house?
Brian J. Maas
I know, but there are next to none that can be run off 200A residential single phase service. The standard size stud welding power supply can
produce 150KVA. A 200A residential service can do 48KVA if my math is right.
Yes I'm using welded wire fabric, but reinforcing wire in this type of construction is used soley for crack or "temperature" control. 3 stories plus a basement, yet the floor plan is small, no need for indoor partions though!
My recollection of the one or two times I have seen one of those stud machines is that they set the stud very quickly, probably less than a second per stud (I welcome a more knowlegable refinement of this guess). If setting a stud utilizes a 150 kva pulse of one second duration and assuming considerable inefficiency, then for that second the service is being asked to provide four times it's rating. But if the draw then goes to zero for the next three seconds the time averaged draw is at or under the rated 48 kva. If the breaker is a slow blow thermal type like you would use for a motor it will also be likely to have a duty cycle that will allow this to happen (I don't know if that type breaker is acceptable in that application). Consult with the electric company for confirmation of this purely theoretical analysis but at least in theory your service would run that machine. Voltage drop is another consideration.
A machine with an engine of course eliminates these problems, Perhaps not available though.
I wish you many years of contented occupation of your new house.
Bill
Bill,
We have stud guns in the shop and a dual gun machine on a trailer that we use in the field. I had to write a welding procedure for the process, and in researching for information, I found that typical weld times for stud diameters is as follows: 1/4" diameter @ .20-.40 seconds, 3/8" diameter @ .30-.45 seconds, 1/2" diameter @ .45-.60 seconds, 5/8" diameter @ .60-.80 seconds, 3/4" diameter @ .80-1.6 seconds, and 1" diameter @ 1.0-1.2 seconds.
http://www.nelsonstud.com/
Here is link to Nelson Stud's web page, I had to contact then recently for manuals and such on one of our stud guns. They seem to be a very freindly and helpful bunch.
John Wright
If you had alot of studs to do then I would definetly try and get one. It will also save you alot of hole cutting.
Brian J. Maas
If you can't rent a stud welding set-up, I would just SMAW weld them as you mentioned. Only, I would make your holes 1" to allow the full 1/4" fillet all around, and still tie in the sheet decking.
As an alternate, you might consider using 7/16" or 3/8" studs, but more of them, and make your holes 13/16" or 3/4" to allow the required 3/16" fillets. (I assume, that as the owner you have a good deal of latitude on construction criteria, but are trying to stay in code compliance.)
I would use the biggest size of E7018 that you can still get a good weld with. For that matter, E7028 (jet-rod) would work well for you and it strikes easily, and will run on an AC machine.
It is not at all unusual to weld studs with SMAW. We end up doing just that whenever our stud gun or the control box break down and we have to get the job out. Naturally, using a stud gun is the fastest and easiest method. But forward progress with a slower method is better than no progress at all.
Chet Guilford
I've got to tell you, I've never heard of or seen shear studs being required on joists. The joists just aren't designed for that application. Shear studs are typically placed on the beams supporting the concrete. So, I think you should check this out. Is this an engineered project? Is Special Inspection required?
Next. The angle used in the cords of the type joists your most likely using is probably 3/16" thick. The amps required to shoot a 1/2" stud is in the neighborhood of between 800 and 900, see where this is headed. I'm not trying to be a smart ass here, just trying to save you some grief.
If there is anytjing else I can confuse you with!
Wayne
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