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.