WOW,
You're asking alot from us here. There are advantages and disadvantages to each of the processes you listed. What processes are you currently using? What type of environment are you welding in(a shop, outside on a jobsite, etc.)? And what are you fabricating?
Let's start with these questions first.
John Wright

Seems to be the engineers should be explaining to US the benefits and differences; thats why they get the big bucks.

Looks to me like the guys are over their heads...
...but maybe they already do know something. I doubt they have pictures of the boss he dont want anybody to see.

The question is a mighty tall order; very broad and comprehensive and a sufficiently detailed response would probably serve as some kind of doctorial thesis. As an alternative it might be more practical to compare what is currently being used to the merits of other processes.

Hope I helped
d

SMAW- Shielded Metal Arc Welding

Advantages
Low equipment cost.
Quick Change from one material to another.
The process lend itself to welding in confined spaces and various positions with few problems.
Deposition Rates faster then GTAW Manual
Easy to move from one location to another
Some special electrodes are made for cutting/gouging
Requires no outside shielding gas and can be used outdoors in light to medium wind.

Disadvantages
Low deposition rate compared to GMAW/FCAW
Filler metal cost can be greater due to a low deposition efficiency that can vary greatly with stub length.
Production factor is typically lower (Unless welding on various materials)
Needs more hand eye coordination.


GMAW-Gas Metal Arc Welding

Advantages
High deposition efficiency when used in certain transfer modes.
No Slag to chip
The process can be used on thin materials with relative ease if properly set.
Low Hydrogen
High production factor since no slag is required to be removed and uses a continuous electrode.
With the parameters properly set for the application, anyone can weld after a very short amount of practice.

Disadvantages
Requires a Wire Feeder which is difficult to move and can sometimes be a maintanence/repair burden.
Needs Shielding Gas
No slag system so out of position welds are sometimes more difficult.
Increased chance of lack of fusion if parameters and welding technique is not controlled.
The gun is difficult to get into tight places.
Is not suitable for windy conditions.

GTAW- Gas Tungsten Arc Welding

Advantages

No slag (Unless using fluzed rods), No Spatter
The low energy input allows the welder to control the puddle with ease compared to other processes. (Only because the amount of molten metal is low comapared to other processes IMO)
Autogenous welds can be made (No Filler metal required)
Because the welder can vary the amount of filler metal and can also manipulate the torch easily, the process is good for welding root passes in joints accessable from one side only.
Can be used on a very wide range of base metals relatively easily.
Wide range of thicknesses
All that is required is a stick welder and the proper gas to weld Alum, SS, CuNI,Carbon Steel etc.

Disadvantages

V E R Y low deposition rate
Requires shielding gas
The welder must manipulate both the torch and filler metal. (A little harder in a mirror sometimes or restiricted access locations)
Requires more manual dexterity than GMAW/FCAW.
Requires tungsten electrode.
Thought by many to be "better" than everything else but in my opinion it is just another process.
AND
:) Sometimes leads to "Golden Arm Syndrome" that results in starched Khaki shirts, red bandannas with $100.00 worth of 316L swagelock fittings holding it together, tungsten holders fabricated out of various alloys with more swagelock fittings, the inability to weld on anything that is not round with a hole in it, and the constant belief that the last job and the next job are better than the one you are on.




G Austin
http://www.weldinginspectionsvcs.com