Heavy Hex Nut

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Heavy Hex Nuts are the industry standard for high-pressure and high-temperature bolting, distinguished by their greater wall thickness and larger width across flats compared to standard nuts. Designed to be paired with stud bolts on ANSI flanges and pressure vessels, they provide a significantly larger bearing surface to distribute clamping loads, preventing dilation and stripping under extreme stress. Manufactured to strict dimensional standards like ASME B18.2.2 and ASME B18.2.4.6M, these nuts are critical for safety in refineries and power plants. At Inconel Fasteners, we forge Heavy Hex Nuts from resilient superalloys such as Inconel 718, 625, and Alloy A286, ensuring they maintain proof load capabilities in environments where extreme thermal cycling and corrosive media would compromise standard fasteners.

Detailed Specifications

Size Range
M12 to M120 Metric 1/2” to 6″ Imperial
Dimensional Standards
ASME B18.2.2 (Imperial) ASME B18.2.4.6M (Metric) ISO 4033
Type of Threads
UNC (Coarse) 8UN (Constant Pitch) Metric Coarse UNF (Fine)
Thread Fit & Tolerance
Class 2B (Standard Fit) Class 3B (High Precision) 6H Tolerance (Metric)
Type of Manufacturing
Hot Forging (Primary) Machined from Hex Bar Cold Forming (Sizes < 1")
Raw Material Origin
Indian Origin European Origin Japanese Origin US Origin Korean Origin
Finish Part Origin
Made in India Custom Origin per Request
Surface Coating (Anti-Seize)
Molybdenum Disulfide (MoS2) Silver Plating Xylan / PTFE Cadmium Plain / Oil Black
Marking
Manufacturer Logo Grade ID (e.g., 660, 718) Heat Code
Heat Treatment Details
Solution Annealing Age Hardening Precipitation Hardening
Delivery Terms
Ex-Works (EXW) FOB CIF CFR DDP
Packing Type
Carton Boxes Wooden Pallets Export Worthy Packing
Payment Methods
L/C (Letter of Credit) T/T (Wire Transfer) Western Union
Certifications
ISO 9001:2015 PED 2014/68/EU MTC EN 10204 3.1
Additional Certifications
NABL Approved Lab Reports Proof Load Test Certificate Hardness Test Report
Mandatory & Additional Requirements
Positive Material Identification (PMI) Wedge Tensile Test Intergranular Corrosion Test (IGC)

Available Inconel Grades & Standards

Dimensions Chart (ASME B18.2.2 Heavy Hex Nut)

Nominal Size
(Inch)		 Width Across Flats (WAF)
(Wrench Size)		 Width Across Corners
(Min)		 Nut Thickness
(Height)		 Thread Per Inch
(TPI - UNC/8UN)
1/2" 7/8" 1.01" 31/64" 13
5/8" 1-1/16" 1.22" 39/64" 11
3/4" 1-1/4" 1.44" 47/64" 10
7/8" 1-7/16" 1.66" 55/64" 9
1" 1-5/8" 1.87" 63/64" 8
1-1/8" 1-13/16" 2.09" 1-7/64" 8
1-1/4" 2" 2.30" 1-7/32" 8
1-3/8" 2-3/16" 2.52" 1-11/32" 8
1-1/2" 2-3/8" 2.74" 1-15/32" 8
1-5/8" 2-9/16" 2.96" 1-19/32" 8
1-3/4" 2-3/4" 3.17" 1-23/32" 8
2" 3-1/8" 3.61" 1-31/32" 8
2-1/4" 3-1/2" 4.04" 2-13/64" 8
2-1/2" 3-7/8" 4.47" 2-29/64" 8
3" 4-5/8" 5.34" 2-59/64" 8

Chemical Composition (Inconel Grades)

Grade Ni (Nickel) Cr (Chromium) Fe (Iron) Mo (Molybdenum) Nb (Niobium) Ti (Titanium) Other Elements
Inconel A286 (Gr. 660) 24.0 - 27.0% 13.5 - 16.0% Balance 1.0 - 1.5% - 1.9 - 2.35% V 0.1 - 0.5%, Al 0.35%
Inconel 718 50.0 - 55.0% 17.0 - 21.0% Balance 2.8 - 3.3% 4.75 - 5.5% 0.65 - 1.15% Al 0.2 - 0.8%
Inconel 625 58.0% Min 20.0 - 23.0% 5.0% Max 8.0 - 10.0% 3.15 - 4.15% 0.4% Max Al 0.4% Max
Inconel X-750 70.0% Min 14.0 - 17.0% 5.0 - 9.0% - 0.7 - 1.2% 2.25 - 2.75% Al 0.4 - 1.0%
Inconel 800 30.0 - 35.0% 19.0 - 23.0% 39.5% Min - - 0.15 - 0.60% Al 0.15 - 0.60%
Inconel 825 38.0 - 46.0% 19.5 - 23.5% 22.0% Min 2.5 - 3.5% - 0.6 - 1.2% Cu 1.5 - 3.0%
Inconel 600 72.0% Min 14.0 - 17.0% 6.0 - 10.0% - - - Mn 1.0%, C 0.15%

Mechanical Properties (Heavy Hex Nuts)

Grade Tensile Strength
(MPa / N/mm²) Min		 Yield Strength
(0.2% Offset) Min		 Proof Load Stress
(MPa) Min		 Hardness
(HRC / HB)
Inconel A286 (Gr. 660) 895 - 1000 585 - 750 585 MPa 24 - 35 HRC
Inconel 718 1275 1035 1035 MPa 36 - 44 HRC
Inconel X-750 1100 700 700 MPa 30 - 40 HRC
Inconel 625 827 414 414 MPa 145 - 220 HB
Inconel 800 520 205 205 MPa 75 HRB (Max)
Inconel 825 586 241 241 MPa 135 - 165 HB
Inconel 600 550 240 240 MPa 65 - 85 HRB

DIN Standards for Bolts

Comprehensive list of dimensional standards for industrial fasteners.

Series 100 - 900
  • DIN 186
  • DIN 188
  • DIN 261
  • DIN 444
  • DIN 479
  • DIN 580
  • DIN 601
  • DIN 603
  • DIN 604
  • DIN 605
  • DIN 610
  • DIN 787
  • DIN 797
  • DIN 931
  • DIN 933
  • DIN 933 SZ
Nuts & Precision
  • DIN 431
  • DIN 439 A/B
  • DIN 466
  • DIN 467
  • DIN 508
  • DIN 547
  • DIN 548
  • DIN 555
  • DIN 557
  • DIN 562
  • DIN 582
  • DIN 798
  • DIN 917
  • DIN 934
  • DIN 935
  • DIN 936
  • DIN 937
Studs & Washers
  • DIN 525
  • DIN 835
  • DIN 938
  • DIN 939
  • DIN 940
  • DIN 976
  • DIN 125 A/B
  • DIN 126
  • DIN 127 A/B
  • DIN 433
  • DIN 440 R/V
  • DIN 6796
  • DIN 7980
  • DIN 9021
Extended & Heavy Series
DIN 3570
DIN 7968
DIN 7969
DIN 7990
DIN 7992
DIN 70613
DIN 70614
DIN 80705
DIN 6331
DIN 6334
DIN 6915
DIN 6924
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