Electric-Resistance-Welded Carbon Steel and Carbon Manganese Steel Boiler and Superheater Tubes A178/A178M Archives

Electric-Resistance-Welded Carbon Steel and Carbon Manganese Steel Boiler and Superheater Tubes A178/A178M

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Designation: A178/A178M
Standard Specification for Electric-Resistance-Welded Carbon Steel and CarbonManganese Steel Boiler and Superheater Tubes This standard is issued under the fixed designation A 178/A 178M; the number immediately following the designation indicates the year of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon (e) indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.





Scope
This 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.NOTE 1—Type C and D tubes are not suitable for safe-ending for forge welding The tubing 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. 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. Optional supplementary requirements are provided and when desired, shall be so stated in the order. The values stated in either inch-pound units or SI units are to be regarded separately as standard. Within the text, the SI units are shown in brackets. The values stated in each system are not exact equivalents; therefore, each system must be used independently of the other. Combining values from the two systems may result in nonconformance with the specification. The inch-pound units shall apply unless the “M” designation of this specification is specified in the order.








Manufacture
The steel for Grade D shall be killed. 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 controlledatmosphere 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 Requirements
Composition, %
Element	Grade A, low carbon steel	Grade C, medium carbon steel	Grade D, carbon-manganese steel
Cacbon	0.06-0.18	0.35 max	0.27 max
Manganese	0.27-0.63	0.80 max	1.00-1.50
Phosphorus, max	0.035	0.035	0.030
Sulfur, max	0.035	0.035	0.015
Silicon	…	…	0.10 max
The steel shall conform to the requirements as to chemical composition prescribed When a grade is ordered under this specification, supplying an alloy grade that specifically requires the addition of any element other than those listed is not permitted.

Tensile requirements
		Grade C	Grade D
Tensile strength, min., ksi [MPa]		60 [415]	70 [485]
Yield strength, min., ksi [MPa]		37 [255]	40 [275]
Elongation in 2 in., or 50 mm, min., %		30	30
For longitudinal strip tests a deduction for each 1⁄32-in. [0.8 mm] decrease in wall thickness below 5⁄16 in. [8 mm] from the basic minimum elongation of the following percentage points shall be made		1.50^A	1.50^A


^ASee minimum elongation values
Wall Thickness of Tubes, in. [mm]		Height of Crushed Section, in. [mm]
		Grade A Tubes	Grade C and D Tubes
0.135 [3.43] and under		3⁄4 [19] or until outside folds are in contact	Crush tests not required
Over 0.135 [3.43]		11⁄4 [32]	…
Grade C and D tubes shall conform to the requirements as to tensile properties prescribed NOTE 3—Explanatory Note—For purposes of design the following tensile properties may be assumed for Grade A tubes:

Tensile strength, min, ksi [MPa] 47 [325]			47 [325]
Yield Strength, min, ksi [MPa]			26 [180]
Elongation in 2 in. or 50 mm, min, %			35
Crush Test
When required by the purchaser, crushing tests shall be made on sections of tube 21⁄2in. [63 mm] in length which shall stand crushing longitudinally without cracking, splitting, or opening at the weld, as follows: This table gives the computed minimum elongation values for each 1⁄32-in. [0.8 mm] decrease in wall thickness. Where the wall thickness lies between two values shown above, the minimum elongation value shall be determined by the following equation: E = 48t + 15.00 [E = 1.87t + 15.0] where: E = elongation in 2 in. or 50 mm, %, and, t = actual thickness of specimen, in. [mm]. For tubing less than 1 in. [25.4 mm] in outside diameter, the length of the specimen shall be 21⁄2 times the outside diameter of the tube. Slight surface checks shall not be cause for rejection.








Mechanical Tests Required
Flattening Test: For Grade A, one flattening test shall be made 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. For Grades C and D, one flattening test shall be made on specimens from each of two tubes from each lot (Note 2) or fraction thereof. Flange Test: For Grade A, one flange test shall be made 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. For Grades C and D, one flange test shall be made 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 A 450/A 450M. Crush Test—For Grade A, when required by the purchaser, one crush test shall be made 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. Tension Test—For Grades C and D, one tension test shall be made 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, which are produced from the same heat of steel. When final heat treatment is in a batch-type furnace, a lot shall include only those tubes of the same size and the same heat which are heat treated in the same furnace charge. When the final heat treatment is in a continuous furnace, a lot shall include all tubes of the same size and heat, heat treated in the same furnace, at the same temperature, time at heat, and furnace speed Reverse Flattening Test—One reverse flattening test shall be made on each 1500 ft [450 m] of finished tubing. Hydrostatic or Nondestructive Electric Test—Each tube shall be subjected to either the hydrostatic or the nondestructive electric test. The purchaser may specify which test is to be used.
















Minimum elongation values
Wall Thickness			Elongation in 2 in. or 50mm, min, %^A
in.		mm
⁵⁄₁₆ (0.312)		30	30
⁹⁄₃₂ (0.281)		28	29
¹⁄₄ (0.250)		27	27
⁷⁄₃₂ (0.219)		26	26
³⁄₁₆ (0.188)		24	24
⁵⁄₃₂ (0.156)		23	22
¹⁄₈ (0.125)		21	21
³⁄₃₂ (0.094)		20	20
¹⁄₁₆ (0.062)		18	18
^ACalculated elongation requirements shall be rounded to the nearest whole number

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