This specification covers carbon and alloy steel pipe, electric-fusion-welded with filler metal added, fabricated from pressure-vessel-quality plate of several analyses and strength levels and suitable for high-pressure service at high temperatures. Heat treatment may or may not be required to attain the desired mechanical properties. The pipes are classified according to steel grades and are designated in classes according to the type of heat treatment performed in the pipe manufacture, whether the weld is radiographically examined, and whether the pipe has been pressure tested. The steel welds shall be made either manually or automatically by an electric process involving the deposition of filler metal. The welded joints shall have positive reinforcement at the center of each side of the weld. The contour of this reinforcement shall be smooth, and the deposited metal shall be fused smoothly and uniformly into the plate surface. The joints shall undergo tension, bend and pressure tests. Unacceptable surface imperfections shall be removed by grinding or machining. The depression after grinding or machining shall be blended uniformly into the surrounding surface. Repair of weld and base metal defects shall be done by welding.

1.1 This specification² covers carbon and alloy steel pipe, electric-fusion-welded with filler metal added, fabricated from pressure-vessel-quality plate of several analyses and strength levels and suitable for high-pressure service at high temperatures. Heat treatment may or may not be required to attain the desired mechanical properties or to comply with applicable code requirements. Supplementary requirements are provided for use when additional testing or examination is desired.

1.2 The specification nominally covers pipe 16 in. [400 mm] in outside diameter and larger with wall thicknesses up to 3 in. [75 mm] inclusive. Pipe having other dimensions may be furnished provided it complies with all other requirements of this specification.

1.3 Several grades and classes of pipe are provided.

1.3.1 Grade designates the type of plate used as listed in Table 1.

1.3.2 Class designates the type of heat treatment performed in the manufacture of the pipe, whether the weld is radiographically examined, and whether the pipe has been pressure tested as listed in 1.3.3.

1.3.3 Class designations are as follows (Note 1):

1.4 Optional requirements of a supplementary nature are provided, calling for additional tests and control of repair welding, when desired.

1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.