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ASTM A178 Boiler Tube|ASTM A178 Tubing
The ASTM A178 standard covers minimum-wall-thickness, electric-resistance-welded tubes made of carbon steel and carbon-manganese steel intended for use as boiler tubes, superheater tubes, and heat exchanger tubes.
1. ASTM A178 Boiler Tube Materials:
- Grade A, Grade C, Grade D Boiler steel tube.
2. ASTM A178 Boiler Tube Size:
- OD: 1/2in-5in (12.7-127mm).
3. ASTM A178 Boiler Tube Wall Thickness:
- 0.035in-0.360in (0.9-9.1mm).
4. ASTM A178 Boiler Tube Different Names:
- Condenser steel tube, heat-exchanger tube, low carbon steel pipe, resistance-welded steel tube, boiler flues, superheater flues, and safe ends, ERW carbon steel pipes.
5. ASTM A178 Boiler Tube Chemical Composition:
- See the provided table for the percentage of elements in Grade A, Grade C, and Grade D.
|
Element % |
ASTM A178 Gr A / SA178A |
ASTM A178 Gr C / SA178C |
ASTM A178 Gr D / SA178D |
|
Low carbon steel |
Medium Carbon Steel |
Manganese Steel |
|
|
C |
0.06-0.18 |
0.35 Max |
0.27 Max |
|
Mn |
0.27-0.63 |
0.80 Max |
1.00-1.50 |
|
P |
0.035 |
0.035 |
0.03 |
|
S |
0.035 |
0.035 |
0.015 |
|
Si |
... |
... |
0.10 Min. |
6. ASTM A178 Boiler Tube Mechanical Properties:
- Tensile Strength, Yield Strength, and Elongation for Grade A, Grade C, and Grade D.
|
Item |
ASTM A178 Gr.A / SA178A |
ASTM A178 Gr.C / SA178C |
ASTM A178 Gr.D / SA178D |
|
Tensile strength, min, ksi [MPa] |
47[325] |
60[415] |
70[485] |
|
Yield strength, min, ksi [MPa] |
26[180] |
37[255] |
40[275] |
|
Elongation in 2 in. or 50mm, min, % |
35 |
30 |
30 |
|
For longitudinal strip tests a deduction for |
1.50A |
1.50A |
1.50A |
|
Each1⁄32-in[0.8mm] decrease in wall thickness below 5⁄16in. [8mm] |
|||
|
From the basic minimum elongation of the following percentage points shall be made |
|||
7. ASTM A178 Boiler Tube Referenced Documents:
- ASTM standards, including A450/A450M Specification, E213 Practice for Ultrasonic Examination, and E273 Practice for Ultrasonic Examination of Longitudinal Welded Pipe and Tubing.
8. ASTM A178 Boiler Tube Manufacturing Process:
8.1. Raw Material Selection: The primary materials used in ASTM A178 boiler tubes are low-carbon steel or carbon-manganese steel. These materials are selected based on their suitability for the intended application and compliance with the ASTM A178 standard.
8.2. Tube Formation: The manufacturing process typically begins with flat steel strips or coils. These strips are passed through a series of rollers to form a tubular shape. The edges of the strip are then joined together by either resistance welding or high-frequency induction welding.
8.3. Welding: ERW (Electric-Resistance-Welded) In the resistance welding process, the edges of the strip are heated and pressed together under pressure to create a strong welded joint. In high-frequency induction welding, an electric current is induced in the strip, causing it to heat up and form a weld when pressed together.
8.4. Heat Treatment (if necessary): Depending on the specific requirements of the application, the welded tubes may undergo heat treatment processes such as annealing or normalization to improve their mechanical properties and remove residual stresses from the welding process.
8.5. Dimensional Control: After welding and any necessary heat treatment, the tubes are subjected to dimensional inspection to ensure they meet the specified requirements of the ASTM A178 standard in terms of outer diameter, wall thickness, and length.
8.6. Surface Treatment: The tubes may undergo surface treatment processes such as pickling or shot blasting to remove any surface oxides, mill scale, or other contaminants that could affect their performance in service.
8.7. Final Inspection and Testing: Once the tubes have been formed, welded, and treated, they undergo a series of quality control checks to ensure they meet the requirements of the ASTM A178 standard. This may include visual inspection, dimensional inspection, non-destructive testing (such as ultrasonic or eddy current testing), and mechanical testing (such as tensile, hardness, or impact testing).
8.8. Packaging and Shipment: Finally, the tubes are typically bundled, packaged, and prepared for shipment to the customer, where they will be used in various boiler, superheater, or heat exchanger applications.
9. ASTM A178 Boiler Tube Heat Treatment:
- Tubes are heat-treated at a specified temperature and cooled. Cold-drawn tubes undergo heat treatment after the final cold-draw pass.
10. ASTM A178 Boiler Tube Surface Condition:
- Finished tubes shall be free of scale, with a slight amount of oxidation considered acceptable.
11. ASTM A178 Boiler Tube Mechanical Tests Required:
- Flattening Test, Flaring Test, Flange Test, Crush Test, Tension Test, Reverse Flattening Test, Hydrostatic or Nondestructive Electric Test.
12. ASTM A178 Boiler Tube Outside diameter and Wall Thickness Tolerance:
|
Outside Diameter tolerance |
Wall thickness tolerance |
||
|
OD < 50 |
±0.05mm |
S < 4mm |
±12.5% |
|
OD > 50 |
±1% |
4--20mm |
-120 |
|
|
|
S≧20mm |
±12.5% |
The ASTM A178 Boiler Tubes, covering their materials, dimensions, chemical composition, mechanical properties, manufacturing process, heat treatment, surface condition, and required mechanical tests.
ASTM A178 Condenser steel tube
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