The prefix “E” designates an electrode as in other specifications. The letters “ER” indicate that the filler metal may be used either as an electrode or a rod.For A5.18, the number 70 indicates the required minimum tensile strength, as a multiple of 1000 psi, of the weld metal in a test weld made in accordance with specification A5.18. Similarly, for A5.18M.

The letter “S” designates a solid electrode or rod.don't forget also can use non copper coated welding wire.

This specification includes filler metals classified as ER70S-G [ER48S-G], E70C-G [E48C-G], andE70C-GS [E48C-GS]. ER80S-G.The “G” (multiple pass) or “GS”(single pass) indicates that the filler metal is of a “general”classification.