This specification governs electric fusion welded pipe used in high-temperature or corrosive environments. There are five distinct classes covered under ASTM B474: Class 1, Class 2, Class 3, Class 4 and Class 5. Each Class outlines the type of welding and xray that is required. The purchaser should select the class when quoting or ordering to this specification. Full penetration welding is required as is heat treatment. Mechanical testing is also required.
- Class 1—Pipe to be double welded with filler metal; the entire weld will be x-ray.
- Class 2—Pipe to be double welded with filler metal; no x-ray is required.
- Class 3—Pipe to be single welded with filler metal; the entire weld will be x-ray.
- Class 4—Same as Class 3 but the weld pass exposed to the inside of the pipe surface does not require the addition of filler metal.
- Class 5—Pipe to be double welded with filler metal; the weld area on the pipe will undergo spot x-ray.
Recommended Heat Treatment:
|Alloy||UNS Designation||PWHTA, B
Deg. F. (Deg. C)
|200 (Ni)||N02200||1650-1700 (900 to 928)||Rapid Air/water|
|201 (Low C)||N02201||1650-1700 (900 to 928)||Rapid Air/water|
|400 (Ni-Cu)||N04400||1650-1700 (900 to 928)||Rapid Air/water|
|X (Ni-Cr-Mo-Fe)||N06002||2150 (1177)C||Rapid Air/water|
|C22D (Low C-Ni-Mo-Cr)||N06022||2050-(1120)C||Rapid Air/water|
|G30D (Ni-Cr-Fe-Mo-Cu)||N06030||2150 (1177)C||Rapid Air/water|
|C2000D(Ni-Cr-Mo-Cu)||N06200||2075-2125 (1135-1163)B||Rapid Air/water|
|230D (Ni-Cr-W-Mo)||N06230||2150-2250 (1177-1232)B||Rapid Air/water|
|600 (Ni-Cr-Fe)||N06600||1800-1850 (983 to 1010)||Rapid Air/water|
|601 (Ni-Cr-Fe-Al)||N06601||1600-1650 (874 to 900)E||Rapid Air/water|
|625 (Ni-Cr-Mo-Cb) Grade 1||N06625||1600 (871)C||Rapid Air/water|
|625 (Ni-Cr-Mo-Cb) Grade 2||N06625||2000 (1093)C||Rapid Air/water|
|G3D (Ni-Cr-Fe-Mo-Cu)||N06985||2100-2150 (1147 to 1177)B||Rapid Air/water|
|Alloy 20 (Cr-Ni-Fe-Mo-Cu-Cb)||N08020||1700-1850 (927 to 1010)||Rapid Air/water|
|…||N08024||1925-1975 (1052 to 1079)||Rapid Air/water|
|…||N08026||2050-2200 (1121 to 1204)||Rapid Air/water|
|825 (Ni-Fe-Cr-Mo-Cu)||N08825||1700-1800 (930 to 980)E||Rapid Air/water|
|C276 (Low C-Ni-Mo-Cr)||N10276||2050 (1121)C||Rapid Air/water|
|B2 (Ni-Mo)||N10665||1950 (1065)C||Rapid Air/water|
|B3D (Ni-Mo)||N10675||1950 (1065)C||Rapid Air/water|
A Recommended temperatures—Different temperatures may be selected by either the purchaser or the manufacturer.
B Set temperatures, ±25°F (±14°C).
C Minimum set temperature.
D Registered Trademark of Haynes International.
E Heat treatment is highly dependent on intended service temperature — consult material manufacturer for specific heat treatments for end use temperature.
- Note this data is for overview only. For full specification and current revisions, please contact ASTM.