Carbon Steel Pipes

Three specifications cover most carbon steel pipe sold in this market and they are not interchangeable. ASTM A106/A106M is seamless only, formulated for high-temperature service, and runs from NPS 1/8 to NPS 48 in grades A, B and C. ASTM A53/A53M covers both black and hot-dipped zinc-coated pipe from NPS 1/8 to NPS 26 (DN 6 to DN 650) in Type F furnace-butt-welded, Type E electric-resistance-welded and Type S seamless, grades A and B; it is intended for mechanical and pressure applications and is accepted for ordinary steam, water and air lines. API Spec 5L covers PSL 1 and PSL 2 line pipe for pipeline transportation in the petroleum and pipeline industries, in grades A25, A and B and the X grades from X42 to X80.

Dimensions for all of them follow ASME B36.10M, which standardises the outside diameters and wall thicknesses of welded and seamless wrought steel pipe for high or low temperatures and pressures. Pipe is therefore ordered by nominal pipe size and schedule, not by a measured diameter.

Choose the specification by service rather than by price. A high-temperature or high-pressure line, a boiler connection or a refinery utility normally calls for A106 seamless; a plant air, firewater or general service line is usually A53; a buried transmission line is API 5L. Galvanised pipe is A53 hot-dipped zinc-coated and should not be welded without removing the coating at the joint.

State on enquiry: specification and grade, seamless or welded, NPS and schedule, length, end finish (plain, bevelled or threaded and coupled), black or galvanised, and whether a mill test certificate is required.