Head Configurations
- Finished Hex & Heavy Hex (ASME B18.2.1 / DIN 931)
- Full Thread Tap Bolts (DIN 933 / ISO 4017)
- Socket Head Cap Screws (ASME B18.3 / DIN 912)
- 12-Point Flange & Countersunk Designs
- Special Drilled Shank & Safety Wire Heads
ISO 9001:2015Certified quality management
PED 2014/68/EUApproved by TUV Rheinland
EN 10204 3.1 / 3.2Heat-number traceability
Since 2010Exporting worldwide
Engineered Fastener Solutions
Industrial Hex Head Bolts for Demanding Global Applications
Hexagon head bolts are primary external threaded mechanical fasteners designed for insertion into clear-drilled holes in flanged connections, structural assemblies, and pressure-retaining casings. TorqBolt produces both standard finished hex bolts and heavy hex bolts with thickened head profiles to distribute high clamping preloads without crushing flange faces.
Whether required in standard dimensional envelopes according to ASME B18.2.1, ISO 4014, and DIN 931 or custom engineered to client drawings with cross-drilled heads or special shank tolerances, our production facilities deploy modern hot forging, precision cold heading, and multi-axis CNC turning. Every production lot adheres to strict metallographic controls to eliminate stress concentration and hydrogen embrittlement risks.
Supplied routinely with EN 10204 3.1 certification or 3.2 third-party inspection endorsements by DNV, Lloyd's Register, Bureau Veritas, or TUV Rheinland, our hex head bolting delivers verified mechanical strength and total heat pedigree from raw bar to final shipment.
Threading & Tolerances
- Thread Profiles: UNC, UNF, 8UN, Metric Coarse & Fine
- Pitch Fit: ASME Class 2A / 3A, ISO 6g / 4h6h
- Rolled Threads for superior fatigue & continuous grain flow
- Metric: M6 to M100 diameters | Imperial: 1/4" to 4"
- Lengths: From 10 mm up to 3000 mm continuous
Quality & Testing
- 100% Heat-Number Traceability to Melt Mill
- EN 10204 3.1 & Independent 3.2 Inspection
- Tensile, Yield, Elongation & Proof Load Verification
- Charpy V-Notch Impact Testing down to -196 °C
- NACE MR0175 / ISO 15156 Sour Service Compliance
Manufacturing Scope
Dimensional & Manufacturing Standards Matrix
TorqBolt produces standard and custom threaded bolts following leading international industrial standards. Below is an overview of standard classifications supported across our production line:
Hexagon & Heavy Hex
- ASME / ANSI B18.2.1
- ASME / ANSI B18.2.3.1M
- DIN 931 (Partial Thread)
- DIN 933 (Full Thread)
- ISO 4014 / ISO 4017
- BS 1768 / BS 1769 / BS 3692
- UNI 5731 / 5737 / 5739
Studs & Threaded Rod
- ASME B18.2.1 Continuous
- DIN 976 / DIN 975 Rod
- DIN 938 / DIN 939 Tap-End
- DIN 2510 Waisted Shank
- BS 4439 / BS 2693
- BS 4882 Flange Bolting
- Custom Double-End Studs
Mating Hex Nuts
- ASME B18.2.2 Heavy Hex
- ASME B18.2.4.6M Metric
- ASTM A194 / A563
- DIN 934 / DIN 936 Jam Nut
- ISO 4032 / ISO 4033 / ISO 4035
- UNI 5587 / 5588 / 5589
- BS 1768 / BS 1083 / BS 3692
Mating Washers
- ASME B18.21.1 / B18.22.1
- ASTM F436 Hardened Steel
- ISO 7089 Plain Washers
- DIN 125 / DIN 9021 Large OD
- DIN 127 Spring Lock Washers
- BS 4320 / BS 3410 / BS 4464
- Belleville Disc Washers
Alloy Metallurgy
Material Grades & Severe Environment Capabilities
Fastener integrity depends on correct alloy selection tailored to operational temperature, chemical media, cyclic fatigue, and pressure containment requirements. We maintain certified inventories across the following alloy families:
| Alloy Family | Common Grades | Applicable Standard | Service Profile & Strengths |
|---|---|---|---|
| Nickel Superalloys | Inconel 625, Inconel 718, Incoloy 825, Hastelloy C276, Hastelloy B2, Monel 400, Monel K-500, Waspaloy | ASTM B637, ASTM B446, ASTM B574, ASTM F467/F468 | Superior creep-rupture strength up to 700 °C, outstanding resistance to oxidizing acids, sour gas (H₂S), and wet chlorine gas. |
| Duplex & Super Duplex | Duplex 2205 (UNS S32205 / S31803), Super Duplex 2507 (UNS S32750), Zeron 100 (UNS S32760) | ASTM A479, ASTM A182 F51 / F53 / F55, NORSOK M-650 | Exceptional resistance to pitting and crevice corrosion (PREN > 40); yield strength double that of standard austenitic steels in marine/subsea environments. |
| Titanium Alloys | Titanium Grade 2 (Commercial Pure), Titanium Grade 5 (Ti-6Al-4V) | ASTM B348, ASTM F467, ASTM F468, AMS 4928 | High strength-to-weight ratio, complete immunity to ambient marine seawater attack, and high cryogenic fracture toughness. |
| High-Performance Stainless | AISI 316L, 317L, 310S, 321, 347, 904L, 254-SMO, AL-6XN, Nitronic 50, Nitronic 60 | ASTM A193 B8/B8M, ASTM A320, ISO 3506-1 A2/A4 | Broad spectrum corrosion protection across food processing, petrochemical piping, cryogenic vessels, and offshore process skids. |
| Precipitation Hardening | 17-4 PH (AISI 630), 15-5 PH, A286 (Alloy 660) | ASTM A564, ASTM A453 Grade 660 | High tensile and yield performance attained via age hardening; suited for valve stems, high-temperature manifolds, and rotating components. |
| Copper Nickel & Bronzes | Cupronickel 70/30, Cupronickel 90/10, Silicon Bronze, Phosphor Bronze, Aluminum Bronze | ASTM B151, ASTM B98, ASTM B150 | Superior biofouling resistance, macrofouling resistance, and durability in commercial maritime, marine condensers, and naval desalination units. |
Supported Material Classifications
Standard and non-standard fastener grades manufactured to order across our CNC and forging division:
Inconel 718 Inconel 625 Inconel 600 Inconel 601 Inconel X750 Hastelloy C276 Hastelloy C22 Hastelloy B2 Monel 400 Monel K-500 Duplex 2205 Super Duplex 2507 Zeron 100 Titanium Grade 2 Titanium Grade 5 17-4 PH 15-5 PH A286 Alloy 660 AISI 316L AISI 316Ti AISI 310S AISI 321 AISI 347 AISI 904L 254 SMO AL-6XN Nitronic 50 Nitronic 60 Incoloy 800H Incoloy 825 Incoloy 925 Waspaloy Nimonic 80A Nimonic 90 MP35N Alloy 20 Aluminium 7075 Cupronickel 70/30 Cupronickel 90/10 Silicon Bronze Phosphor Bronze
Protective Finishes
Engineered Coatings & Anti-Corrosion Surface Treatments
In harsh offshore, coastal, and chemical refinery conditions, surface treatments provide essential barrier protection, prevent galvanic cell creation, and regulate torque-tension ratios during bolt makeup.
Fluoropolymer & PTFE
Xylan®, PTFE, and fluorocarbon systems delivering extremely low friction coefficients (0.06–0.08), eliminating galling in stainless and nickel fasteners and surviving 3,000+ hours in ASTM B117 salt fog testing.
PTFE Fluorocarbon Ceramic Fluoropolymer Xylan 1070 / 1424
Zinc & Barrier Platings
Sacrificial anodic protection compliant with ASTM A153, ASTM B633, and ISO 10684 for structural, outdoor marine, and general engineering installations requiring durable corrosion shielding.
Hot Dip Galvanizing Electro Zinc Plating Dacromet 320/500 Zinc-Nickel Plating
Specialty Functional Finishes
Engineered finishes designed for uniform electrical grounding, high-temperature oxidation resistance, chemical passivation, and thread galling resistance on subsea and aerospace bolting.
Silver Plating Electroless Nickel Phosphate Coating Passivated (ASTM A967)
Technical FAQ
Frequently Asked Questions — Hex Head Bolts
What is the difference between a standard hex bolt and a heavy hex bolt?
A heavy hex bolt (ASME B18.2.1) has a wider width-across-flats (wrench size) and a slightly thicker head profile than a standard finished hex bolt of identical nominal diameter. Heavy hex bolts provide a larger bearing area, which distributes high bolt tension over a broader surface to prevent embedment or flange galling in high-pressure piping, valves, and structural connections governed by ASTM A193, A320, or A325.
How do you prevent thread galling in stainless steel and nickel alloy hex bolts?
Austenitic and nickel superalloys develop spontaneous passive oxide films that can cold-weld under heavy tightening pressure. To prevent thread galling, TorqBolt utilizes precision thread rolling rather than cut threads (producing smoother root finishes and compressed grain flow), pairs bolts with nuts having slightly differing hardness (at least 30 HB differential), and offers anti-galling coatings such as silver plating, molybdenum disulfide, or fluoropolymer (PTFE) systems.
What documentation is included with TorqBolt hex head bolts?
Each batch ships with an EN 10204 3.1 Inspection Certificate documenting the original mill melt heat number, chemical composition, tensile strength, 0.2% offset yield strength, percentage elongation, Charpy V-notch impact values (where required), hardness test results, and dimensional conformance. EN 10204 3.2 third-party inspection witnessed by TUV, DNV, Lloyd's, or Bureau Veritas is available upon request.
Can you manufacture custom dimensions and drawing-specific hex bolts?
Yes. In addition to standard ANSI/ASME and DIN/ISO metrics, we routinely manufacture custom-length bolts up to 3000 mm, stepped shanks, reduced-shank fatigue designs, drilled bolt heads for safety wiring, special thread pitch combinations (such as 8UN on large diameters), and proprietary customer drawing requirements.
Are TorqBolt hex bolts approved for pressure equipment under PED 2014/68/EU?
Yes. TorqBolt holds manufacturer certification under the European Pressure Equipment Directive (PED 2014/68/EU) verified by TUV Rheinland, authorizing us to supply bolting materials with verified impact properties and full traceability for pressurized vessels, boiler systems, and piping manifolds across Europe and global export projects.
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