Tap End Stud Bolts / Half Thread Stud

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Tap End Stud Bolts, often called Half-Thread or Double-End Studs, are engineered for "blind hole" applications where one end of the fastener is permanently screwed into a machined component (like a pump casing, valve body, or engine block) while the other accepts a nut. Distinguished by an unthreaded shank in the middle, these studs feature a short "Tap End" designed for a secure, often interference-fit engagement, and a longer "Nut End" for clamping. At Inconel Fasteners, we manufacture these to ASME B18.31.2 standards with precise tap-end lengths (1D, 1.5D, to 2.5D) to suit specific mating materials. Forged from high-strength superalloys like Inconel 718 and A286, our tap end studs provide the extreme shear strength required to prevent thread stripping in high-vibration turbine and manifold assemblies.

Detailed Specifications

Size Range
M6 to M80 Metric 1/4” to 3-1/2″ Imperial
Tap End Length (T)
1D (For Steel Threads) 1.5D (For Cast Iron) 2.5D (For Aluminum) Custom Lengths
Type of Threads
UNC / UNF Metric Coarse / Fine UNC x UNF (Mixed Threads) Class 5 (Interference Fit)
Dimensional Standards
ASME B18.31.2 DIN 938 (1D) DIN 939 (1.25D) DIN 835 (2D) IFI 136
Type of Manufacturing
Rolled Threads (High Fatigue) Cut Threads (Small Batches) CNC Machined Body
Raw Material Origin
Indian Origin European Origin Japanese Origin US Origin
Finish Part Origin
Made in India Custom Origin per Request
Surface Coating
Plain / Oil Black Manganese Phosphate Zinc Nickel Silver Plating (High Temp) Thread Locker Patch
Marking
Grade ID on Nut End Manufacturer Logo Traceability Code
Heat Treatment Details
Solution Annealing Age Hardening Stress Relieving
Delivery Terms
Ex-Works (EXW) FOB CIF DDP
Packing Type
Small Cartons (Weight Controlled) Wooden Pallets Thread Protectors (Net/Cap)
Payment Methods
L/C (Letter of Credit) T/T (Wire Transfer)
Certifications
ISO 9001:2015 API 20E / 20F MTC EN 10204 3.1
Additional Certifications
Ultrasonic Test (UT) Magnetic Particle Inspection (MPI) Thread Gauging Report
Mandatory Requirements
Positive Material Identification (PMI) Concentricity Check Surface Roughness Check

Available Inconel Grades & Standards

Dimensions Chart (ASME B18.31.2 / DIN 939)

Nominal Size
(Dia)		 Tap End Length (T)
(Fixed: ~1.25D)		 Nut End Length (B)
(Variable)		 Unthreaded Shank (S)
(Standard)
M10 / 3/8" 12.5 mm 22mm - 100mm Dia Equivalent
M12 / 1/2" 15.0 mm 25mm - 150mm Dia Equivalent
M16 / 5/8" 20.0 mm 30mm - 200mm Dia Equivalent
M20 / 3/4" 25.0 mm 35mm - 250mm Dia Equivalent
M24 / 1" 30.0 mm 40mm - 300mm Dia Equivalent
M30 / 1-1/4" 38.0 mm 50mm - 350mm Dia Equivalent
M36 / 1-1/2" 45.0 mm 60mm - 400mm Dia Equivalent
M42 / 1-3/4" 52.5 mm 70mm - 450mm Dia Equivalent

Chemical Composition (Inconel Grades)

Grade Ni (Nickel) Cr (Chromium) Fe (Iron) Mo (Molybdenum) Nb (Niobium) Ti (Titanium) Other Elements
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 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%
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 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%

Mechanical Properties (Tap End Studs)

Grade Tensile Strength
(MPa / N/mm²) Min		 Yield Strength
(0.2% Offset) Min		 Elongation
(%) Min		 Hardness
(HRC / HB)
Inconel 718 1275 1035 12% 36 - 44 HRC
Inconel A286 (Gr. 660) 895 - 1000 585 - 750 15% 24 - 35 HRC
Inconel X-750 1100 700 15% 30 - 40 HRC
Inconel 625 827 414 30% 145 - 220 HB
Inconel 825 586 241 30% 135 - 165 HB

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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