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    2. Grade B8ML4CUN Nuts

    ASTM A194 Grade B8ML4CUN Heavy Hex Nuts — UNS S31730

    Advanced corrosion-resistant heavy hex nuts for critical industrial service.

    ASTM A194/A194M Grade B8ML4CuN Nuts are engineered from high-alloy stainless steel materials to deliver exceptional corrosion resistance and mechanical reliability. These nuts are suitable for offshore, desalination, and chemical process industries requiring premium fastening solutions. They are regularly combined with ASTM A193/A193M stud bolts in corrosive process systems and are compatible with ASTM A320/A320M low-temperature bolting requirements. ASTM A563M and ASTM F2437/F2437M specifications further support their integration into specialized engineering projects.

    ASTM A194/A194M Grade B8ML4CUN Chemical Requirements

    Grade Description
    and
    UNS Designation    		 C Mn P SE Si Cr Ni Mo N Cu
    ASTM A194/A194M Grade B8ML4CuN (317) S31730 0.030 2.00 0.040 0.010 1.00 17.0-19.0 15.0-16.5 3.0-4.0 0.045 4.0-5.0
    • (A) Total aluminum, soluble and insoluble.
    • (B) Maximum, unless minimum or range is indicated.
    • (C) Where ellipses (...) appear in this table there is no requirement.

    ASTM A194/A194M Grade B8ML4CUN Hardness Requirements

    Grade and Type Completed Nuts
    Brinell Hardness Rockwell Hardness
    C Scale B Scale
    ASTM A194/A194M Grade B8ML4CUN 126 to 300 32 max 60 min

    ASTM A194/A194M Grade B8ML4CUN Proof Load Requirements (Inch Series)

    Nominal Size, in. Threads per Inch Stress Area in. 2 Proof Load, lbf A
    Grade B8ML4CUN
    Heavy HexH HexI
    1/4 20 0.0316 2 540 2 380
    5/16 18 0.0524 4 190 3 930
    3/8 16 0.0774 6 200 5 810
    7/16 14 0.1063 8 500 7 970
    1/2 13 0.1419 11 350 10 640
    9/16 12 0.182 14 560 13 650
    5/8 11 0.226 18 080 16 950
    3/4 10 0.334 26 720 25 050
    7/8 9 0.462 36 960 34 650
    1 8 0.606 48 480 45 450
    11/8 8 0.790 63 200 59 250
    11/4 8 1.000 80 000 75 000
    13/8 8 1.233 98 640 92 450
    11/2 8 1.492 119 360 111 900
    • (A) See limit for proof load test in 8.2.2.1. The proof load for jam nuts shall be 46 % of the tabulated load.
    • (B) Based on proof stress of 130 000 psi.
    • (C) Based on proof stress of 120 000 psi.
    • (D) Based on proof stress of 150 000 psi.
    • (E) Based on proof stress of 135 000 psi.
    • (F) Based on proof stress of 175 000 psi.
    • (G) Based on proof stress of 150 000 psi.
    • (H) Based on proof stress of 80 000 psi.
    • (I) Based on proof stress of 75 000 psi.

    ASTM A194/A194M Grade B8ML4CUN Proof Load Requirements (Metric Series)

    Nominal Size, mm Threads Pitch Stress Area mm 2 Proof Load, kNA
    Grade B8ML4CUN
    Heavy HexH HexI
    M6 1.0 20.1 11.1 10.4
    M8 1.25 36.6 20.1 18.8
    M10 1.50 58.0 31.9 29.9
    M12 1.75 84.3 46.4 43.4
    M14 2.0 115.0 63.3 59.2
    M16 2.0 157.0 86.4 80.9
    M20 2.5 245.0 134.8 126.2
    M22 2.5 303.0 166.7 156.0
    M24 3.0 353.0 194.2 181.8
    M27 3.0 459.0 252.5 236.4
    M30 3.5 561.0 308.6 288.9
    M36 4.0 817.0 449.4 420.8
    • (A) See limit for proof load test in 8.2.2.1. The proof load for jam nuts shall be 46 % of the tabulated load.
    • (B) Based on proof stress of 895 MPa.
    • (C) Based on proof stress of 825 MPa.
    • (D) Based on proof stress of 1035 MPa.
    • (E) Based on proof stress of 930 MPa.
    • (F) Based on proof stress of 1205 MPa.
    • (G) Based on proof stress of 1035 MPa.
    • (H) Based on proof stress of 550 MPa.
    • (I) Based on proof stress of 515 MPa.

    Related A194 Grades & References

    ASTM A194 Grade B8ML4CUN (UNS S31730) belongs to the modified-316 family. Related grades: Grade 2H, Grade 8, Grade 8M, Grade 8T. Dimensions: ASME B18.2.2 heavy hex. Full standard: ASTM A194 PDF. A194 hub.

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