Grade
Identification Markings
Grade Identification
MarkingSpecificationMaterialNominal Size, In.Proof Load Stress, ksiHardness
RockwellSee NoteMinMax
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No Mark
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ASTM A563 Grade O
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Carbon Steel
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1/4 - 1-1/2
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69
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B55
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C32
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2,3
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ASTM A563 Grade A
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Carbon Steel
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1/4 - 1-1/2
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90
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B68
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C32
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2,3
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ASTM A563 Grade B
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Carbon Steel
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1/4 - 1
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120
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B69
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C32
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2,3
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>1 - 1-1/2
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105
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ASTM A563 Grade C
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Carbon Steel, may be
Quenched and Tempered
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1/4 - 4
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144
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B78
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C38
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4
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ASTM A563 Grade C3
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Atmospheric Corrosion
Resistant Steel, may be Quenched and Tempered
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1/4 - 4
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144
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B78
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38
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4,6
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