This time, I’ll introduce a structural pipe standard to everyone: Standard Specification for Cold-Formed Welded and Seamless Carbon Steel Structural Tubing in Rounds and Shapes, Ok, let’s start:
This specification covers cold-formed welded and seamless carbon steel round, square, rectangular, or special shape structural tubing for welded, riveted, or bolted construction of bridges and buildings, and for general structural purposes. The sizes with a periphery of 64 in. (1630mm) or less, and a specified wall thickness of 0.625in. (16mm) or less, the material grade D requires heat treatment.
- Material and Manufacture
In this specification, there mentioned four material grades: Grade A Grade B, Grade C, and Grade D. It covers three processes of the steel type: open-hearth, basic-oxygen, or electric-furnace.
The tubing shall be made by a seamless or welding process. The welded tubing is normally furnished without removing the inside flash.
- Chemical Composition & Mechanical Property
There was a table requests the chemical composition of each grade, and the heat analysis shall be in accordance with table requirement. Grade A, B, and D have the same requirement of the chemical composition. Methods and practices relating to chemical analysis shall be in accordance with Test Methods, Practices, and Terminology A751.
Grade D tubing shall be heat treated at a temperature of at least 1100F°(590℃) for one hour per inch of thickness.
The tensile properties shall according to table 2 in the specification.
- Test – Flattening Test
The flattening test shall be made on round structural tubing, no required for shaped structural tubing. For the welded round structural tubing, the test specimen at least 4in. (100mm) in length shall be flattened cold between parallel plates in three steps, with the weld located 90° from the line of direction of the force. For the seamless round structural tubing, 2 3/8in. (60mm) specified outside diameter and larger, a specimen not less than 2 1/2in (65mm) in length. There shall no creak or break on the inside or outside surfaces.