1.1 This specification covers electric fusion welded pipe suitable for high-temperature or corrosive service as listed in . (Although no restrictions are placed on the sizes of pipe that may be furnished under this specification, commercial practice is commonly limited to sizes not less than 8 in. (203 mm) nominal diameter.)

1.2 Five classes of pipe are covered as follows:

1.2.1 Class 1 -- Pipe shall be double welded by processes employing filler metal in all passes and shall be completely radiographed.

1.2.2 Class 2--Pipe shall be double welded by processes employing filler metal in all passes. No radiography is required.

1.2.3 Class 3 -- Pipe shall be single welded by processes employing filler metal in all passes and shall be completely radiographed.

1.2.4 Class 4 -- Same as Class 3 except that the weld pass exposed to the inside pipe surface may be made without the addition of filler metal.

1.2.5 Class 5 -- Pipe shall be double welded by processes employing filler metal in all passes and shall be spot radiographed.

1.3 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to become familiar with all hazards including those identified in the appropriate Material Safety Data Sheet for this product/material as provided by the manufacturer, to establish appropriate safety and health practices, and determine the applicability of regulatory limitations prior to use.