ASTM A178 Grade A Electric-Resistance-Welded Steel Tubes
ASTM A178 Grade A Electric-Resistance-Welded Steel Tubes 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 furnac
Description
ASTM A178 Grade A Electric-Resistance-Welded Low-Carbon Steel Boiler and Superheater Tubes
ASTM A178 specification covers 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.
ASTM A178 Grade A Low-Carbon Steel Boiler Tubes Quick Details
Type：Electric-Resistance-Welded
Outside Diameter ：12.7mm-127mm
Wall thickness：0.9mm-9.1mm
Length：6000mm、12000m or specified length as required.
Type of End-Finish：Plain End、Beveled End、Treaded
Surface treatment: Tubes will be varnished (Outside only) to prevent rust.
ASTM A178 Grade A Low-Carbon Steel Boiler Tubes sizes and thicknesses usually furnished to this specification are 1 ⁄ 2 to 5 in. [12.7 to 127 mm] in outside diameter and 0.035 to 0.360 in. [0.9 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 this specification.
Manufacture
Tubes shall be made by electric-resistance welding.
Heat Treatment
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°C] or higher.
Chemical Composition
| Element | Composition, % |
| Grade A,Low-Carbon Steel |
|
| Carbon | 0.06–0.18 |
| Manganese | 0.27–0.63 |
| Phosphorus, max | 0.035 |
| Sulfur, max | 0.035 |
| Silicon | …. |
Tensile Requirements
| Tensile strength, min, ksi [MPa] | 47 [325] |
| Yield Strength, min, ksi [MPa] | 26 [180] |
| Elongation in 2 in. or 50 mm, min, % | 35 |
Mechanical property requirements do not apply to tubing smaller than 1 ⁄ 8 in. [3.2 mm] in inside diameter or 0.015 in. [0.4 mm] in thickness
Mechanical Tests Required
Flattening Test:
Flange Test:
Crush Test
Reverse Flattening Test
Hydrostatic or Nondestructive Electric Test
Forming Operations
When inserted in the boiler, tubes shall withstand expanding and beading without showing cracks or flaws, or opening at the weld. When properly manipulated, superheater tubes shall withstand all forging, welding, and bending operations necessary for application without developing defects.