Black steel pipe is uncoated steel, also known as black steel. The dark color comes from iron oxide that forms on its surface during manufacturing. When the steel pipe is forged, a black oxide skin is formed on its surface, giving it the finish seen on this type of pipe. Material Standard: ASTM, ASME and API; High Temperature Steel Pipe: ASTM A106 Gr. B/C, API 5L Gr. B, ASTM A53 Gr. B; Low Temperature Steel Pipe: ASTM A333 Gr. 3/6X; High Yield Steel Pipe: API 5L Gr. X42/X46/X52/X56/X60/X65/X70/X80and higher. PSL-1/PSL-2; Form: Round, Square, Rectangular Etc; Outer Diameter: 20MM~508MM; Wall thickness: SCH 10. SCH 20, SCH 40, SCH STD, SCH 80, SCH XS, to SCH 160; Length Range: 20 FT (6 meter), 40FT (12 meter)or customized; Ends Type: Beveled ends, Plain ends; End Protection: plastic Caps or iron Caps;