ASTM A178, identical with ASME SA-178, is the standard specification covering minimum-wall-thickness, electric-resistance-welded tubes made of carbon steel and carbon-manganese steel intended for use as boiler tubes, boiler flues, superheater flues, and safe ends. There are three grades available: Grade A – low-carbon steel, Grade C – medium-carbon steel, Grade D – carbon-manganese steel.
The tubing sizes and thicknesses usually furnished to ASTM A178 are 1/2″ to 5″ [12.7 mm to 127 mm] in outside diameter and 0.035″ to 0.320″ [0.9 mm to 9.1 mm], inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with all other requirements of ASTM A178/ ASME SA-178.
|Element||ASTM A178/ ASME SA-178|
|Grade A||Grade C||Grade D|
|ASTM A178||Grade C||Grade D|
|EL. in 2"|
The ASTM A178 Grade D steel shall be killed. ASTM A178 tubes shall be made by electric-resistance welding process. After welding, all tubes shall be heat treated at a temperature of 1650°F [900°C] or higher and followed by cooling in air or in the cooling chamber of a controlled-atmosphere furnace. Cold-drawn tubes shall be heat treated after the final cold-draw pass at a temperature of 1200°F [650°F] or higher.
ERW tubes made from ASTM A178 steel may be tested or inspected in the following ways covering crush test, flattening test, flange test, tension test, reverse tension test, hydrostatic test, nondestructive electric test, dimension inspection, visual examination, as well as ultrasonic inspection.