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ASTM A 278 - Standard for Gray Iron Castings
for Pressure Containing Parts
This specification covers gray iron for castings suitable for
pressure-containing parts for use at temperatures up to 650°F
(350°C).
Classes of Iron:
1. Castings of all classes are suitable for use up to 450°F (230°C).
For temperatures above 450°F and up to 650°F, only Class 40, 45, 50,
55, and 60 castings are suitable.
2. Castings of all classes are suitable for use up to 230°C. For
temperatures above 230°C and up to 350°C, only Class 275, 300, 325,
350, 380, and 415 castings are suitable.
Heat Treatment:
1. Whether or not heat treatment is required for Class 40, 45, 50,
55, and 60 castings to be used at temperatures at 450°F or less.
2. Whether or not heat treatment is required for Class 275, 300,
325, 350, 380, and 415 castings to be used at temperatures at 230°C
or less.
Tensile Requirements
| Class of Iron |
Tensile Strength, min, MPa |
| No. 20 |
20 |
| No. 25 |
25 |
| No. 30 |
30 |
| No. 35 |
35 |
| No. 40 |
40 |
| No. 45 |
45 |
| No. 50 |
50 |
| No. 55 |
55 |
| No. 60 |
60 |
| No. 150 |
150 |
| No. 175 |
175 |
| No. 200 |
200 |
| No. 225 |
225 |
| No. 250 |
250 |
| No. 275 |
275 |
| No. 300 |
300 |
| No. 325 |
325 |
| No. 350 |
350 |
| No. 380 |
380 |
| No. 415 |
415 |
Chemical
Composition
1. Class 40, 45, 50, 55, and 60 castings intended for service above
450°F (230°C) shall have a maximum carbon equivalent of 3.8 % as
calculated from the equation CE = %C + 0.3 (%Si + %P). The maximum
phosphorus and sulfur contents shall be 0.25 % and 0.12 %,
respectively.
2. Class 275, 300, 325, 350, 380, and 415 castings intended for
service above 230°C shall have a maximum carbon equivalent of 3.8 %
as calculated from the equation CE = %C + 0.3 (%Si + %P). The
maximum phosphorus and sulfur contents shall be 0.25 % and 0.12 %,
respectively.
3. The chemical analysis for total carbon shall be made on either
chilled cast pencil-type specimens or thin wafers approximately 1⁄32
in. thick cut from test coupons. Drillings shall not be used because
of attendant loss of graphite.
Workmanship, Finish, and Appearance
1. All castings shall be made in a workmanlike manner and shall
conform to the dimensions on drawings furnished by the purchaser. If
the pattern is supplied by the purchaser without drawings, the
dimensions of the casting shall be as predicted by the pattern.
2. The surface of the casting shall be free of adhering sand, scale,
cracks, and hot tears as determined by visual examination. Other
surface discontinuities shall meet the visual acceptance standards
specified in the order.
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