Welds produced by welding electrodes offer a minimum tensile strength in pounds per square inch (PSI), according to Metal Web News. The first couple of digits in a type of electrode indicate the tensile strength of the weld it produces in thousands of PSI. Welding electrodes rated at 6011 and 6013 will create a weld with a tensile strength of 60,000 PSI. A 7018 electrode produces 70,000 PSI tensile strength welds.
Electrodes need to be held in certain positions to create welds efficiently. The second to last digit found in the electrode designation indicates the position in which welders must use the electrode. According to Metal Web News, a "1" indicates that the electrode can be used in any position, while a "2" indicates that the electrode must be held flat and horizontal.
Outer coatings increase welding efficiency and also help maintain the integrity of the electrode throughout its life. The last digit on an electrode indicates the type of coating on the electrode. A "1" indicates the presence of a cellulose potassium coating, a "5" indicates a low hydrogen sodium coating and "6" indicates a low hydrogen potassium coating, according to Welding Tips and Tricks.