ASTM A250 / ASME SA250 / Electric Resistance Welded Carbon Molybdenum Alloy Steel Boiler and Superheater Tubes supplier & distributor in India

ASTM A 250-89a / ASME SA 250

ELECTRIC RESISTANCE WELDED CARBON

MOLYBDENUM ALLOY STEEL BOILER AND SUPERGEATER TUBES

This standard is issued under the fixed designation A 250/A 250M; 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 ( ε) indicates an editorial change since the last revision or reapproval.

1.Scope

1.1 This specification covers several grades, designated T1, T1a, T2, T11, T12, and T2, of minimum-wall-thickness, electric-resistance-welded, carbon-molybdenum and chromium-molybdenum alloy-steel, boiler and superheater.

1.2 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 0.320 in. [0.9 to 8.1 mm], inclusive, in minimum wall thickness. Tubing having other dimensions may be furnished, provided such tubes comply with al other requirements of this specification.

1.3 Mechanical property requirements do not apply to tubing smalle than 1/8 in. [3.2 mm] in inside diameter or 0.015 in. [0/4 mm] in thickness.

1.4 The values stated in either inch-pound units or SI units are to be regarded separately as the 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.

Chemical composition

Grade	Mfg. Process	Chemical composition(%)
Grade	Mfg. Process	C	Si	Mn	P	S	Ni	Cr	Mo	Others
T1	E	0.10~0.20	0.10~0.50	0.30~0.80	0.045Max	0.045Max	-	-	0.44~0.65	-
T1a	E	0.15`0.25	0.10~0.50	0.30~0.80	0.045Max	0.045Max	-	-	0.44~0.65	-
T1b	E	0.14Max	0.10~0.50	0.30~0.80	0.045Max	0.045Max	-	-	0.44~0.65	-
T2	E	0.10~0.20	0.10~0.50	0.30~0.81	0.030Max	0.020Max	-	0.50~0.81	0.44~0.65	-
T11	E	0.05~0.15	0.10~0.50	0.30~0.60	0.030Max	0.020Max	-	0.80~1.25	0.44~0.65	-
T12	E	0.05~1.15	0.50Max	0.30~0.61	0.030Max	0.020Max	-	0.80~1.25	0.44~0.65	-
T22	E	0.15Max	0.50Max	0.30~0.60	0.030Max	0.020Max	-	1.90~2.60	0.87~1.13	-

Mechanical Properties

Grade	Tensile Test MPa or N/mm2		Remaks (Similar to JIS)	Possibility Temperature
Grade	Min Yield point	Tensile Strength	Remaks (Similar to JIS)	Possibility Temperature
T1	205	380Min	(STBA12)
T1a	220	415Min	(STBA13)
T1b	195	365Min	-
T2	205	415Min	-
T11	205	415Min	-
T12	205	415Min	-
T22	205	415Min	-

Chemical Composition

The steel shall conform to the requirements as to chemical composition prescribed in Table

TABLE 1 Chemical Requirements

Element	Composition, %
Element	Grade T1	Grade T1a	Grade T1b	Grade T2	Grade T11	Grade T12	Grade T22
Carbon	0.10-0.20	0.15-0.25	0.14	0.10-0.20	0.05-0.15	0.05-0.15	0.15
Manganese	0.30-0.80	0.60-0.80	0.30-0.80	0.30-0.61	0.30-0.60	0.30-0.61	0.30-0.60
Phosphorus,max	0.025	0.025	0.025	0.025	0.025	0.030	0.025
Sulfu,max	0.025	0.025	0.025	0.020	0.020	0.020	0.020
Silicon	0.10-0.50	0.10-0.50	0.10-0.50	0.10-0.30	0.50-1.00	0.50	0.50
Molybdenum	0.44-0.65	0.44-0.65	0.44-0.65	0.44-0.65	0.44-0.65	0.44-0.65	0.87-1.13
Chromium				0.50-0.81	1.00-1.50	0.80-1.25	1.90-2.60

TABLE 2 Number of Tubes in a Lot Heat Treated by the Continuous Process

Size of Tube	Size of Lot
2 in.[50.8 mm]and over in outside diameter and 0.22 in. [5.1mm]and over in wall thickness	not more than 50 tubes
Less than 2 in. [50.8 mm] but over 1 in. [25.4 mm] in outside diameter or over 1 in. [25.4 mm] in outside diameter and under 0.200 in. [5.1 mm]in wall thickness	not more than 75 tubes
1 in. [25.4 mm] or less in outside diameter	not more than 125 tubes

TABLE 3 Tensile Requirements

Grade	T1	T1a	T1b	T2	T11	T12	T22
Tensile strength, min, ksi[MPa]	55 [380]	60 [415]	53 [365]	60 [415]	30 [415]	60 [415]	60 [415]
Yleld strength, min, ksi [MPa]	30 [205]	32 [220]	28 [195]	30 [205]	32 [220]	32 [220]	30 [205]
Elongation in 2 in. or 50 mm, min, %	30	30	30	30	30	30	30
For longitudinal strip tests a deduction shall be made for each 1/32-in. [0.8-mm] decrease in wall thickness belw 5/16 in. [8 mm] from the basic minimum elongation of the following percentage points	1.50 A	1.50 A	1.50 A	1.50 A	1.50 A	1.50 A	1.50 A

A The following table gives the computed minimum values:Wall Thicknessin.

Wall Thickness		Elongation in 2 in. or 50 mm, min, % B
in.	mm	Grades T1,T1a, T2, T11, T12, and T22
5/16	8	30
9/32	7.2	29
1/4	6.4	27
7/32	5.6	26
3/16	4.8	24
5/32	4	22
1/8	3.2	21
3/32	2.4	20
1/16	1.6	18

NOTE-The above table gives the computed minimum elongation values for each 1/32-in. [0.8 mm]
decrease n wall thickness. Wall thickness. Where the wall thicness lies between two values shown
above, the minimum elongation value shall be determined by the following equation:

E= 48t + 15.00 [E=1.87t + 15.00]

where: E =elongation in 2 in. or 50 mm in %, and
t = actual thickness of specimen, in. [mm].
B Calculated elongation requirements shall be rounded to the nearest whole number.

TABLE 4 Hardness Requirements

Grade	Brinell hardness Number (Tubes 0.200 in. [5.08 mm] and over in wall thickness	Rockwell Hardness Number (Tubes less than 0.200 in. [5.08 mm] in wall thickness
T1	146	B80
T1a	153	B81
T1b	137	B77
T2	163	B85
T11	163	B85
T12	163	B85
T22	163	B85

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