Calculating Weld Strength

http://www.engineersedge.com/weld_design_menu.shtml

http://www.gowelding.com/calcs/calc.htm

Please reply with any questions/concerns and also, please confirm that you are not designing any critical structures/welds (ie. hopefully you are just looking at a go-kart for your kids or something)

Whoops - that first link should be:

http://www.engineersedge.com/weld_design_menu.shtml

What type of welds are you looking at? Butt, lap, spot welds, fillet welds, etc?

Plus, some additional things you may want to look at:

Material?

What type of equipment do you have access to?

Critical application?

Operator Qualification?

Operating environment your welded artifact will be subjected to?

This is a very hard question to answer with the supplied details. Most welding rods have the tensile strength marked in the rod designation number such as E7018 = 70000 lb PSI tensile. Most normal mild steel shapes are made from A-36 type material and this material is rated somewhere around 36000 PSI tensile. Having said this there is a huge difference in the strength of the weld metal and base metal designed into welding electrodes before one even decides what type weld is to be made. After this there are infinite number of variables than will change the strength of a particular type weld. Things like size of weld, type of weld, materials, design of joint is only a few of the major variables. After one selects the proper weld design, rod, material amperage etc. the next biggest variable is the preparation and cleaning of the base metal in my opinion. Just a small bit of rust, grease, dirt or countless other contaminates can cause defects that will reduce the weld strength immensely. You can go to the ASME, AWS or countless other internet sites and get formulas to estimate weld strength if you know these variables up front. As a general guideline you can assume that on fillet welds you should have a minimum throat of weld thickness equal to or larger than the thinnest piece of base metal you are joining together. Things like gussets and other structural reinforcement designed into a part can change the strength of a joint so much that less weld may be used to accomplish the same end result as well. Hope this helps.

pipewelder