Specifications
Surface Treatments
Certifications
- ISO 9001 - 2015 Certified
- PED 2014/68/EC
- NACE MR0175/ISO 15156-2
- NORSOK M-650
- DFAR
- MERKBLATT AD 2000 W2/W7/W10
Bi-Hex / Double-Hex Bolts
TorqBolt manufactures bi-hex bolts (also called double-hex bolts and 12-point bolts) in A286 and other compatible alloys to AS9100D and ISO 9001:2015 quality systems. Each fastener head carries the struck tB manufacturer ligature plus the A286 (or specified) alloy grade marking for traceability. Three names, one geometry: twelve external splines arranged every 30 degrees around the head. Primarily aerospace and motorsport.
Materials
Alloy choice is set by the spec, the service temperature, the corrosion environment, and the strength target. TorqBolt routinely produces bi-hex bolts (also called double-hex bolts and 12-point bolts) in A286 (UNS S66286), Inconel 718, Ti-6Al-4V (Grade 5), MP35N (UNS R30035), Custom 465 stainless, AISI 8740 chromoly heat-treated, AISI 4340, 17-4 PH H1025 condition, H-11 tool steel, and L19 race-grade alloy steel.
Frequently asked questions
What is a 12-point bolt?
A 12-point bolt has 12 splines arranged every 30 degrees on the OUTSIDE of the bolt head, also called a bi-hex or double-hex bolt. The 12 external splines provide twice the wrench-engagement angles of a standard hex head, allowing higher applied torque before cam-off, which is why aerospace and motorsport applications adopt the geometry.
Are 12-point bolts the same as ISO 14579?
No. ISO 14579 specifies an INTERNAL hexalobular socket head (similar to Torx) recessed inside a cap screw. External 12-point bolts under MS21250 / NAS1351 / AS3216 use an EXTERNAL bi-hex head driven by a 12-point socket wrench. Both involve 12 features but on different sides of the bolt head and require different drivers.
Which alloys does TorqBolt manufacture 12-point bolts in?
TorqBolt produces 12-point bolts in A286 (UNS S66286), Inconel 718 (UNS N07718), Ti-6Al-4V Grade 5, MP35N (UNS R30035), Custom 465 H1025, AISI 8740 chromoly heat-treated, AISI 4340, 17-4 PH, H-11 tool steel, and L19 race-grade alloy steel. Choice depends on tensile target, service temperature, and corrosion environment.
Is TorqBolt AS9100D certified?
Yes. TorqBolt operates under AS9100D Rev D and ISO 9001:2015 quality management systems, audited annually by the registrar. NORSOK M-630 and NACE MR0175 / ISO 15156 qualifications cover offshore and sour-service applications. Mill test reports MTC 3.1 standard and MTC 3.2 critical-service witness are issued with every lot.
What lead time should I expect?
Stock alloys (A286, AISI 8740, AISI 4340, 17-4 PH, 316 stainless) ship in 4 to 6 weeks. Specialty alloys (Inconel 718, MP35N, Custom 465, Ti-6Al-4V, L19) ship in 8 to 12 weeks depending on raw-bar lead time at the alloy producer. Critical-service orders requiring third-party witness inspection (MTC 3.2) add 1 to 2 weeks for witness scheduling.
Why 12 splines outperform 6-point hex
A standard hex (6-point) head allows the wrench to engage at every 60-degree rotation. A 12-point head doubles that, allowing engagement every 30 degrees. In a tight engine bay or aircraft assembly bay where the wrench cannot swing a full 60 degrees between obstacles, the 12-point geometry is the difference between being able to torque the bolt and not. The same alloy in a hex head and a 12-point head reaches the same tensile failure load (set by the bolt body, not the head); the 12-point lets you reach the design preload without cam-off, and the hex sometimes does not.
In aerospace use, the 12-point head appears across the MS21250, NAS1351, AS3216, and NAS6300-series specifications. In motorsport and diesel use, the 12-point appears on aftermarket head studs, connecting rod bolts, and main cap bolts. The internal-hexalobular drive (cap-screw recessed socket per ISO 14579) is a different system and is driven by a Torx-style internal driver, not the 12-point socket. The disambiguation is documented on the External vs Internal 12-Point page.
"Bi-hex" and "double-hex" are regional synonyms
The terms "bi-hex bolts" and "double-hex bolts" are used interchangeably with "12-point bolts" in different regions and industries. "Bi-hex" is more common in European mechanical engineering catalogs, "double-hex" appears in some American military procurement documents, and "12-point" is the standard term in US aerospace and motorsport. All three describe the same external head geometry: 12 splines arranged at 30-degree intervals around the bolt head perimeter, doubling the wrench engagement angles versus a 6-point hex.
Drawing callouts that say "bi-hex" or "double-hex" can be supplied as standard 12-point bolts under MS21250, NAS1351, AS3216, or NAS6303 through NAS6320 spec depending on tensile target and head dimension. The European DIN family (covered on DIN 12-point bolts) and the metric variants on metric 12-point use the same 12-spline head geometry. Confirm the tensile class (10.9 / 12.9 alloy steel, A286 stainless, or specialty alloy) and the head dimensions in the RFQ.
Request a Quote
RFQ to info@torqbolt.com, call +91-22-66157017, or WhatsApp +91-22-66157017. Mill test report (MTC 3.1 standard, 3.2 critical-service) ships with every lot.
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