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
MP35N 12-Point Bolts
MP35N (MP35N (UNS R30035)) 12-point bolts deliver 260 ksi tensile strength in sour-service oil-gas, high-strength aerospace bolting, and aftermarket diesel head studs where extreme tensile strength matters. TorqBolt manufactures the full 12-point geometry range (flange, head, cap-screw, stud) in MP35N to AS9100D and ISO 9001:2015 quality systems. Each bolt head carries the struck tB ligature plus the alloy grade marking.
For deep MP35N metallurgy, chemistry, heat treatment, and equivalent grades see torqbolt.com.
Specifications We Produce
- MS21250, 160 ksi 12-point aerospace bolt
- NAS1351, close-tolerance 12-point
- AS3216, 180 ksi superalloy 12-point
- NAS6303 through NAS6320 tension series
Typical Applications
- Aerospace engine + structural bolting
- Motorsport head studs, rod bolts, main cap bolts
- Diesel-truck performance head studs
- Industrial high-temperature bolting
When to specify this alloy over alternatives
Alloy choice in 12-point bolting is set by the combination of tensile target, service temperature, corrosion environment, and traceability requirement. The default for a generic 160 ksi aerospace bolt is A286 because the supply chain is mature, the AMS specs (5731 / 5732 / 5737) are well documented, and oxidation resistance is good to 700 deg C.
Step up to Inconel 718 when service temperature exceeds 700 deg C or when the joint sees aggressive cyclic stress in jet-engine duty. Step up to MP35N when tensile target is 220+ ksi and the environment is sour-service or saline. Use Ti-6Al-4V when the 56 percent weight savings vs steel matters more than tensile (race-engine main caps, aerospace airframe pylon clip-ups). Use 17-4 PH H1025 when corrosion resistance and 180 ksi tensile both matter and budget rules out cobalt-nickel.
Certification pack with each lot
Mill test report MTC 3.1 ships with every lot at no additional cost: chemistry per the alloy spec, mechanical properties (tensile, yield, elongation at fracture, hardness), microstructure note, and heat-treatment cycle. MTC 3.2 adds third-party witness inspector signature on every test event from raw-bar receiving through final lot acceptance and is required by most aerospace primes for tier-1 critical-service joints. Add MTC 3.2 in the RFQ if your drawing or PO calls for it.
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.
Request a Quote
RFQ to info@torqbolt.com or call +91-22-66157017. Mill test report (MTC 3.1 or 3.2 critical) ships with every lot.
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