This specification covers requirements for resistance spot and seam welding of the following metals and their alloys. Material Groups (1) Group 1??Aluminum and magnesium (2) Group 2??Steel@ nickel@ and cobalt (3) Group 3??Titanium Classification. Classification is based on the following: (1) Class A. A welded joint@ whose failure during any operating condition would cause loss of the equipment or system or one of its major components. (2) Class B. A welded joint whose failure would reduce the overall strength of the equipment or system or limit the intended functioning or use of equipment. (3) Class C. A welded joint for which no stress analysis is required and whose failure would not affect the performance of the equipment or system. Standard Units of Measure. This standard makes use of both U.S. Customary Units and the International System of Units (SI). The latter are shown within brackets [ ] or in appropriate columns in tables and figures. The measurements may not be exact equivalents; therefore@ each system shall be used independently. Safety and Health. Safety and health issues and concerns are beyond the scope of this standard@ and therefore are not fully addressed herein. Safety and health information is available from other sources@ including@ but not limited to@ ANSI Z49.1@ Safety in Welding@ Cutting@ and Allied Processes@ and applicable federal and state regulations.