ASTM A500 is a classification that covers material used for welding and seamless carbon steel structural tubing. The classification has three grades, with Grade C being a newer mixture that is primarily used for roll cages and cold temperatures. ASTM A500 Grade C must meet certain requirements in order to pass impact tests administered by ASTM. Originally known as the American Society for Testing and Materials, ASTM is an international standards developing organization that establishes standards when dealing with metals and other materials used in industrial areas.
According to ASTM rules, all tubing must have the chemical mixtures of carbon, manganese, phosphorus, sulfur and copper present. In addition, the steel produced must be done by open-hearth, basic-oxygen or electric-furnace melting methods. It is not enough to have the correct chemicals mixed in the tubing; materials must also undergo specific welding methods in order to be approved by ASTM A500.
In addition to the three aforementioned steel-producing methods, tubing must also be welded using flat-rolled steel. The flat-rolled steel should be formed into a tube using the electric-resistance welding process. Using the electric-resistance welding process will assist the material in passing the tension and flattening test that evaluates the sturdiness of the piece.
ASTM rules require that the longitudinal butt joint of the tubing be thickly welded in order to assure the secure structural design of the piece. ASTM will not approve tubing that has a weak joint because such weakness may pose a problem to the entire structure. Thousands of structures built with poor still joints would be in danger of collapsing if the ASTM did not uphold this regulation.
Before the manufacturer is given permission to market products, all tubing must be inspected by an ASTM representative. The purpose of the inspection is to assure conformance to structure requirements; tubing that fails to pass inspection must either be corrected or discarded. In addition, the appearance of tubing must be professional and free from defects; it should not, for example. be severely burned or have bumps or blotches of steel in any one place.