ER70S-6 A-Number 1 Chemistry
ER70S-6 is one of the most popular solid wire filler metals for GMAW and GTAW yet it may not comply with the ASME A-No. 1 chemistry limitations for Manganese and Silicon. It is important for those deploying ASME welding procedures with ER70S-6 filler metal listed as A-No. 1 to have procurement quality controls in place to monitor the Manganese and Silicon values on the filler metal MTR.
The ER70S-6 classification chemistry allows for a maximum of 1.85% Manganese and 1.15% Silicon while ASME has placed a limit of 1.60% Manganese and 1.00% for Silicon. Manufacturers of filler metal often produce the filler metal with Manganese and Silicon low enough to comply with the A-No. 1 requirement, but validation is key to remaining in compliance with the welding procedure and ASME Section IX code requirements.
To address the the possible mismatch ASME has developed an ER70S-6A classification. Where the “A” is a supplemental designator indicating compliance to ASME A-No. 1 chemistry.
“A” ASME A-No. 1
“A” is an optional designator of the 5.18 Classification used for “S-6” or ER70S-6 classification, which indicates that the rod meets the additional manganese and silicon requirements for ASME A-No. 1.
A-No. 1 limits require a maximum of manganese limit of 1.60%, and a maximum silicon limit of 1.0%
So a filler metal rod labeled as ER70S-6A indicates conformance to ASME A-No. 1 and can be used on PQR’s and WPS’s in lieu of notes specifying limitations of manganese and silicon.
A comparison of the SFA 5.18 chemistry table to the ASME Section IX A-Number table quickly exposes the fact that ER70S-6 can fall outside the maximum allowable for Manganese and Silicon.
Here is a comparison of deoxidizer content between ER70S-2 and ER70S-6. ER70S-2 has a tradition of being used on the root for piping, which has largely been eroded by the more recent popularity of ER70S-6, largely based on ER70S-6 being less expensive per weight.
