I see Al just responded to your last part of your query, from me, as I don't use ASME codes much I was slow to respond but it appears my direction is in the correct direction.  When you state those aspects of the filler classification you limit the welding contractor and their welders (if they supplied the WPS then they have limited themselves possibly because of a lack of knowledge) to using that particular classification even though it is a non-essential to most all codes.  Most of the time you are free to use only the basic classification such as 'E7018' and leave all the particulars to the welding contractor who may or may not see a need to further restrict their welders (take this slightly differently if you are the welding contractor). 

As Al stated, there are many times when it is important to list, and thus restrict the usage to, these extended classifications.  But one must be careful when doing so.  Don't just grab the electrode info for product on the floor and start filling in the appropriate space on the WPS with absolutely all the information on the sticker. 

The same will apply for the welding parameters.  Just because the manufacturer specifications say you can weld at 100 amps does not mean that is a good range for the work being performed.  You may choose to be more limiting, higher at the low end and/or lower at the high end.

Just my two tin pennies worth.

He Is In Control, Have a Great Day,  Brent

ER70S-2 and -6 are both A5.18, F6 electrodes, so one qualifies for the other without code restriction.
The differenes are:
S-2 electrodes are primarily used for single pass welding of killed, semi-killed and rimmed steels and are well suited for use in single side , melt thru welding without protective root sheilding gas on the backside of the joint. S-2 has additional alloying elements of Ti, Zr and Al, plus lower levels of Mn and SI, as compared to S-6.
S-6 electrodes are intended for both single and multi pass welding . They are especially suited for sheet metal applications where smooth weld beads are desired, and structural and plate steels that have moderate amounts of rust or mill scale.
Both may be used for single or multi pass welding and on the same base metal classifications.
For these reasons and others, the WPS writer may choose to specify a paticular type for internal or customer purposes, and may do so by noting the exact type on the WPS, which is to be adhered to.
If these priorities are not considered crucial for the end product, the WPS writer may choose to leave the option open, simply by specifying the filler metal on the WPS as ER70S, or ER70S-X.

(info from AWS A5.18:2005 Specification for Carbon Steel Electrodes and Rods for Gas Shielded Arc Welding)

Tim Gary

This question was not code specific. One must always check the applicable welding standard. No two are the same. What is permitted by one, may not be allowed by another. Then again, you don't want to impose additional restrictions required by one code on a project if they are not required by the applicable welding standard. D1.5; who says it is applicable to this job? D1.1; who says it applicable to this job? We simply don't know because the original post does not reference a welding standard.

That being said, I'll stay my position that if the WPS lists a specific filler metal classification, a specific brand name, a specific diameter, a very narrow range for the welding parameters, whatever, the welder is obligated to use them.

Making a decision based on what you did on your last job is like pulling the trigger with one empty cylinder. Chances are, you're going to get hurt really bad.

Best regards - Al