ctate,
Do you mean A5.1 Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding and not the D1.5 Bridge Welding Code? I know that sounds like a dumb question but I saw that mistake made once so I figured I'd ask.
D1.1 is the Structural Steel Welding Code and basically it covers design, prequalified welds, qualification of procedures and personnel, quality criteria, NDE, and other information for welding on structural steel.
A5.1 covers manufacturer's testing for mechanical and chemical properties, hydrogen content, and other "stuff" for welding electrodes. Definitely "apples and oranges"
In most cases, you would not need to purchase A5.1 because the electrode manufacturer already takes care of specification compliance for his products, and you should be able to get a C of C indicating that. Most of the testing would need to be performed in a lab anyway, and not in a shop. A5.1 might be interesting reading (or not depending on your viewpoint) but the end user would not normally need to assure compliance other than to obtain the C of Cs.
Chet Guilford