D1.1 is not going to direct you to the best welding process or wire size for this situation.

D1.1 does state maximum single pass fillet weld sizes for prequalified welding procedures (WPSs), so if your goal is to put together a prequalified WPS per D1.1 then certainly take a look at Table 3.7 in the code. If you are welding weathering steels you also need to be aware of 3.7.3. In fact, just make sure you read all the notes to Table 3.7.

You can also go outside the limits of Section 3 (prequalified) but you simply need to run weld tests per Section 4 to qualify the WPS.

submerged arc

If I were you, I'd invite some welding salespeople into your shop to have a look at what you have now and what you want to do.  Yes,they want to make some money off you, but they can be a good source of ideas of what's available that might help you out.

Let us analyze this for a moment.  You say that your company produces a weldment that requires 1/2 in fillet welds and is trying to cut time out of the process in order to make the weldment profitable.

Question 1: Have you checked with the engineer to make sure 1/2 inch fillets are neccesary?  In my experience as a weld engineer designs are almost always overwelded.  This is the first place I would start.

Question 2: Assuming 1/2" welds are needed why would making them in one pass be faster when using GMAW, FCAW or SMAW?  One pass 1/2 in welds will lower the travel speed and most likely introduce undercut and overlap.  Most of the time a 1/2" fillet can be made in three passes more efficiently than a single pass.

Question 3:  What is your current wire feed speed.  I would bet the welders set it however they like.  If you want to increase travel speed thereby reducing the time it takes to make the weld turn up the WFS.  Of course voltage will need to be adjusted accordingly.

Question 4:  Have you looked at anything other than the welding itself? 

Here is an example about drilling a hole.  What do you have to do to drill a hole in a piece of material.  Get the material, 5 minutes, make the set up, 5 minutes, put in the drill bit, 2 min, drill the hole, 4 seconds, remove the part, 1 minute, stack part on pallet, 1 minute, remove the set up, 5 minutes, remove the bit, 2 min.  In this example the only work the customer paid for was drilling the hole which only took 4 seconds, (I just made up the times as an example so don't harp on me about it).  Total time to drill the hole including all the rest of the garbage was  22 minute 4 seconds.  We could speed up the drill and use a better bit and save only a second or two but all the other garbage is still present.

What I am saying is look for other oprotunities to save time before investing in a SAW machine etc.  Speeding up the welders is like getting a better bit.  It only lowers the value added time not the waste.

Also, larger diameter wire does not equal faster or more metal deposited.  Because deposition rate is a function of amperage and cross sectional area of the electrode it is possible to increase the deposition rate by using a smaller diameter wire.  For instance .052 metal core wire running at 27 volts and 280 inches per minute deposits about 7.88 lbs/foot.  .045 metal core wire running 30 volts and 600 ipm will deposit around 12 lbs/ft.  I may be alittle off on the parameters but not much I just don't have the data sheet in front of me.  Metal core could speed up your welding if you weld mostly flat and horizontal welds, look into it.

Questions you should ask yourself.  Do the welders have to walk much to get parts, tools, etc.  Take a sheet of paper out into the shop with you and track a welders movements ofr a few hours by quckly sketching his work area and drawing lines on the paper everytime he walks around, I bet you will be suprised.  If parts are retrieved by the welders get someone else to do it for them so they can continue to work.  How far away are the electrodes?  Can they be moved closer to the work area or an extra spool issued?  Can drums instead of rolls or spools be utilized?  How much grinding is going on? Can this be reduced?  Can someone else do the grinding?  Is there a more effecient way to place the part to allow more welding in one position?  IF out of position welds are being made can the part be rotated so that they can be made in flat or horizontal positions?

Just a few things to think about. 

One last example.  Just this past week I reduced each welders time by 22% just by turning up the WFS (saves $1,110,720.00 per year).  Last year I saved my company 1.4 million dollars by introducing barrels instead of spools.  1.4 million was being wasted just in the time it took to change out spools.  In the last month I increased production by 100% by re-arranging the weld fixtures. (100% increase translates into another 54 million dollars in sold product this year alone, of course we have the demand).  In 2006 I eliminated 12 hours per weldment by designing, building and implementing a rollover fixture.  Many other changes have been made and are being made.  Due to these and other changes our company has grown from 9.6% profit to a little more than 14% profit in just two years.  In dollars the difference is around 18 million, not to shabby I say!  Oh yeah, we also lowered our spending over that time as well, further adding to the profits.