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Stardard ASTM A178/A178M ERW Tube
1. ASTM A178/A178M Scope
1.1 This specification encompasses minimum-wall-thickness, electric-resistance-welded tubes manufactured from carbon steel and carbon-manganese steel, with the intended application for boiler tubes, boiler flues, superheater flues, and safe ends.
*Note 1: Type C and D tubes are not suitable for safe-ending for forge welding.*
1.2 The specified tubing sizes and thicknesses typically range from 1/2 to 5 inches [12.7 to 127 mm] in outside diameter and 0.035 to 0.360 inches [0.9 to 9.1 mm], inclusive, in minimum wall thickness. Tubes with dimensions outside this range may be provided, given compliance with all other requirements of this specification.
1.3 Mechanical property requirements are not applicable to tubing smaller than 1/8 inch [3.2 mm] in inside diameter or 0.015 inch [0.4 mm] in thickness.
1.4 Optional supplementary requirements are available and should be specified in the order.
1.5 Values provided in either inch-pound units or SI units are considered separate standards. While both systems are presented in the text with SI units shown in brackets, combining values from both systems may result in nonconformance. The inch-pound units apply unless the "M" designation of this specification is specified in the order.
2. ASTM A178/A178M Referenced Documents
2.1 ASTM Standards:
- A450/A450M Specification for General Requirements for Carbon and Low Alloy Steel Tubes
- E213 Practice for Ultrasonic Testing of Metal Pipe and Tubing
- E273 Practice for Ultrasonic Testing of the Weld Zone of Welded Pipe and Tubing
3. ASTM A178/A178M Ordering Information
3.1 Orders for material under this specification should include the following details to adequately describe the desired material:
- Quantity (feet, meters, or number of lengths)
- Name of material (electric-resistance-welded tubes)
- Grade (A, C, or D, Table 1)
- Size (outside diameter and minimum wall thickness)
- Length (specific or random)
- Optional requirements (product analysis, Section 7; crush test, Section 10; hydrostatic or nondestructive electric test, 11.6)
- Test report required (Certification Section of Specification A450/A450M)
- Specification designation
- Individual supplementary requirements, if required
- Special requirements
4. ASTM A178/A178M Manufacture
4.1 Grade D steel shall be killed.
4.2 Tubes shall be manufactured by electric-resistance welding.
5. ASTM A178/A178M Heat Treatment
5.1 After welding, all tubes shall undergo heat treatment at a temperature of 1650°F [900°C] or higher, 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.
6. ASTM A178/A178M Composition Specifications
6.1 The steel must adhere to the chemical composition requirements outlined in Table 1.
6.2 If a specific grade is requested under this specification, providing an alloy grade that necessitates the inclusion of any element not listed in Table 1 is strictly prohibited.
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TABLE 1 Chemical Requirements |
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Element |
Composition, % |
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Grade A, Low-Carbon Steel |
Grade C, Medium Carbon Steel |
Grade D, Carbon Manganese Steel |
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Carbon |
0.06–0.18 |
0.35 max |
0.27 max
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Manganese |
0.27–0.63 |
0.80 max |
1.00–1.50
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Phosphorus, max |
0.035 |
0.035 |
0.030
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Sulfur, max |
0.035 |
0.035 |
0.015
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Silicon |
... |
... |
0.10 min |
7. ASTM A178/A178M Product Analysis
7.1 Upon request in the purchase order, the manufacturer or supplier shall conduct a product analysis on one tube per 100 pieces for sizes over 3 inches [76.2 mm] and one tube per 250 pieces for sizes 3 inches [76.2 mm] and under. Alternatively, when tubes are identified by heat, one tube per heat must undergo analysis. The determined chemical composition must conform to the specified requirements.
7.2 In the event of a failure in the original product analysis test, retests on two additional lengths of flat-rolled stock or tubes are mandatory. Both retests, concerning the relevant elements, must meet the specification requirements. Failure to meet these standards may lead to the rejection of all remaining material in the heat or lot (Note 2). At the discretion of the producer, each length of flat-rolled stock or tube may undergo individual testing for acceptance. Tubes or stock not meeting specification requirements shall be rejected.
*Note 2: A lot comprises 250 tubes for sizes 3 inches [76.2 mm] and under and 100 tubes for sizes over 3 inches [76.2 mm], prior to cutting to length.*
8. ASTM A178/A178M General Requirements
8.1 Material supplied under this specification must conform to the applicable requirements of the current edition of Specification A450/A450M unless exceptions are explicitly provided herein.
9. ASTM A178/A178M Tensile Requirements
9.1 Tubes of Grade C and D must meet the specified tensile properties outlined in Table 2.
*Note 3: Explanatory Note: For design purposes, the following tensile properties may be assumed for Grade A tubes:*
9.2 Table 3 provides the computed minimum elongation values for each 1/32-inch [0.8 mm] decrease in wall thickness. If the wall thickness falls between two values shown above, the minimum elongation value shall be determined by the following equation:
\[ E = 48t1 / (15.00) \quad \text{or} \quad E = 1.87t1 / (15.00) \]
where:
\( E \) = elongation in 2 inches or 50 mm, %, and,
\( t \) = actual thickness of the specimen, in inches [mm].
10. ASTM A178/A178M Crush Test
10.1 If specified by the purchaser, crushing tests shall be conducted on sections of tubes 2 1/2 inches [63 mm] in length, which must withstand crushing longitudinally without cracking, splitting, or opening at the weld, as follows:
\[ \text{Wall Thickness of Tubes, in. [mm]} \]
\[ \text{Height of Crushed Section, in. [mm]} \]
\[ \begin{align*} \text{Grade A Tubes} & : 0.135 [3.43] and under - 3/4 [19] or until outside folds are in contact; \text{Crush tests not required} \\ \text{Grade C and D Tubes} & : Over 0.135 [3.43] - 1 1/4 [32] \end{align*} \]
10.2 For tubing less than 1 inch [25.4 mm] in outside diameter, the specimens length shall be 2 1/2 times the outside diameter of the tube. Slight surface checks shall not be cause for rejection.
11. ASTM A178/A178M Mandatory Mechanical Tests
11.1 Flattening Test:
11.1.1 For Grade A, a flattening test is required on specimens from each of two tubes from each lot (Note 2) or fraction thereof, and from each 2000 ft [600 m] or fraction thereof of safe-end material.
11.1.2 For Grades C and D, a flattening test is necessary on specimens from each of two tubes from each lot (Note 2) or fraction thereof.
11.2 Flange Test:
11.2.1 For Grade A, a flange test must be conducted on specimens from each of two tubes from each lot (Note 2) or fraction thereof, and from each 2000 ft [600 m] or fraction thereof of safe-end material.
11.2.2 For Grades C and D, a flange test is mandatory on specimens from each of two tubes from each lot (Note 2) or fraction thereof. The width of the flange shall not be less than 75% of that specified in Specification A450/A450M.
11.3 Crushing Test (Grade A):
When required by the purchaser, a crush test shall be performed on specimens from each of two tubes from each lot (Note 2) or fraction thereof, and from each 2000 ft [600 m] or fraction thereof of safe-end material.
11.4 Tension Test (Grades C and D):
A tension test is to be conducted on specimens from each of two tubes from each lot. The term "lot" for tension test requirements applies to all tubes prior to cutting, of the same nominal diameter and wall thickness, produced from the same heat of steel. For final heat treatment in a batch-type furnace, a lot includes only those tubes of the same size and heat treated in the same furnace charge. In a continuous furnace, a lot includes all tubes of the same size and heat, heat treated in the same furnace, at the same temperature, time at heat, and furnace speed.
11.5 Reverse Flattening Test:
A reverse flattening test is required for each 1500 ft [450 m] of finished tubing.
11.6 Hydrostatic or Nondestructive Electric Test:
Each tube must undergo either the hydrostatic or nondestructive electric test. The purchaser has the option to specify which test is to be used.
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TABLE 2 Tensile Requirements |
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Grade A |
Grade C |
Grade D |
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Tensile strength, min, ksi [MPa] |
47 [325] |
60 [415] |
70 [485] |
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Yield strength, min, ksi [MPa] |
26 [180 |
37 [255] |
40 [275] |
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Elongation in 2 in. or 50 mm, min, % |
35 |
30 |
30 |
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For longitudinal strip tests a deduction for each 1 ⁄ 32 -in. [0.8 mm] decrease in wall thickness below 5 ⁄ 1 6 in. [8 mm] from the basic minimum elongation of the following percentage points shall be made. |
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1.50 A |
1.50 A |
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12. ASTM A178/A178M Forming Operations
12.1 Tubes, when inserted in the boiler, must withstand expanding and beading without exhibiting cracks, flaws, or openings at the weld. Superheater tubes, when manipulated properly, should endure all forging, welding, and bending operations essential for application without developing defects.
13. ASTM A178/A178M Product Marking
13.1 In addition to the marking outlined in Specification A450/A450M, the letters “ERW” must be legibly stenciled on each tube or marked on a tag attached to the bundle or box in which the tubes are shipped.
13.2 The manufacturer’s name or symbol may be permanently placed on each tube by rolling or light stamping before normalizing. If a single stamp is applied by hand, this mark should not be less than 8 inches [200 mm] from one end of the tube.
14. ASTM A178/A178M Keywords
14.1 boiler tube; resistance welded steel tube; steel tube, carbon; welded steel tube
ASTM A178 ERWIN Tube
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