John,
from D1.1 2006
Sent you something in your email
5.3.1.3 Shielding Gas. A gas or gas mixture used for
shielding shall conform to the requirements of AWS
A5.32, Specification for Welding Shielding Gases. When
requested by the Engineer, the Contractor or fabricator
shall furnish the gas manufacturer's certification that the
gas or gas mixture conforms to the dew point requirements
of AWS A5.32. When mixed at the welding site,
suitable meters shall be used for proportioning the gases.
Percentage of gases shall conform to the requirements of
the WPS.