Nuts
Manufacturer
India · Mumbai
Nuts From the Same Certified Heat as Your Stud Bolts
In exotic alloy pressure flange assemblies, the nut is not a secondary component — it is the most corrosion-critical interface in the entire fastener assembly. The nut-stud thread engagement zone and the nut-bearing face against the washer or flange face are the locations of stagnant electrolyte trapped in the crevice geometry. A dissimilar-alloy nut — stainless steel under a Hastelloy B3 stud bolt, or a duplex nut under a Monel K500 stud — creates a galvanic couple that will corrode the less noble material preferentially at exactly the locations where visual inspection cannot reach without disassembly.
Akbar Fasteners Pvt. Ltd. supplies matched-heat nut and stud bolt sets — nuts machined from the same ASTM-certified alloy bar as the matching stud bolts. Same heat number, same MTC, same PMI XRF confirmation. The mill test certificate covers stud bolt and nut under a single document. For EPC and TPI documentation this means: one MTC for the complete stud bolt set, one PMI report, one COC — simplified vendor document submission for all pressure flange stud bolt assemblies.
We manufacture all nut types: ASME B18.2.2 heavy hex (the ASME B16.5 standard flange nut), DIN 934 standard hex, DIN 6334 coupling (barrel) nuts, flanged hex DIN 6923, jam nuts, slotted nuts, castle nuts, and dome nuts — in every exotic alloy from Hastelloy and Monel through Inconel, Incoloy, Nickel 200, stainless steel, and alloy steel ASTM A194 2H.
Matched Heat — Single MTC for Complete Assembly
ASME B18.2.2 heavy hex nuts from the same ASTM-certified heat as matching stud bolts. One MTC, one PMI report, one COC covers the stud + nut assembly for TPI documentation.
8+ Nut Types in All Alloys
Heavy hex, standard hex, coupling, flanged, jam, slotted, castle, and dome nuts — every type in every exotic alloy from Hastelloy through stainless steel and alloy steel A194 2H from M6 to M100.
100% PMI XRF Before Machining
Every nut bar stock PMI-verified before machining — critical for identifying grade substitution in high-value alloys like Hastelloy and Monel where visual inspection cannot distinguish alloys.
Anti-Galling Guidance for Ni-Mo Alloys
Hastelloy B2 and B3 nuts require nickel-based anti-seize and ASME PCC-1 lubrication factor (K) applied to torque calculations. Akbar Fasteners provides anti-seize specifications and torque correction tables with all B2/B3 nut orders.
Exotic Alloy Nut Types & Standards
All nut types manufactured from ASTM-certified exotic alloy bar stock. PMI-verified before production. Matched from same heat as stud bolts and bolts for single-MTC assembly documentation.
Heavy Hex Nuts
The ASME B16.5 standard nut for pressure flange stud bolt sets — wider across-flats (AF) and greater height than DIN 934 standard hex, providing higher bearing area and greater wrench engagement. Matched from same certified heat as ASME B16.5 stud bolts for complete stud bolt set documentation. M12–M100. All exotic alloys.
Standard Hex Nuts
DIN 934 / ISO 4032 standard-height hex nut — the DIN/ISO standard nut for hex bolt assemblies in chemical equipment covers, structural connections, and all applications where ASME B18.2.2 heavy hex is not specified. M6–M100 in all exotic alloys. A4 (316L) and A2 (304) to ISO 4032 for stainless steel applications.
Coupling Nuts (Long Hex)
Long hex nuts for joining two threaded rods or extending stud bolt engagement depth — length approximately 3× the hex width. Used in NaOH plant expansion joints, acid plant structural tie-rod extensions, and wherever two sections of exotic alloy threaded rod must be joined in corrosive service. M6–M100. All exotic alloys.
Flanged Hex Nuts
Hex nuts with integrated plain or serrated flange face — distributes bearing load over greater area without a separate washer, eliminating the washer-nut face crevice where stagnant corrosive media accelerates attack. Used in FRP-lined vessel connections, rubber-lined equipment covers, and composite substrate connections in exotic alloy service. M6–M64.
Jam Nuts (Half Nuts)
Thin (half-height) hex nuts used as locking nuts in conjunction with a full-height nut — the jam nut is tightened against the full nut to create a jam that resists vibration loosening. Exotic alloy jam nuts for vibrating chemical plant equipment, pump body connections, and reactor internals where standard spring lock washers are incompatible with the process environment. M6–M100.
Slotted & Castle Nuts
Slotted (DIN 935) and castle (castellated) nuts with slots for cotter pin or safety wire — for applications requiring positive mechanical locking against rotation: marine propeller shaft connections, offshore structural joints, and chemical plant equipment where nut retention must be confirmed positively rather than relying on torque-preload alone. M6–M100 in exotic alloys.
Dome (Cap) Nuts
Acorn or dome-shaped cap nuts — thread engages partially and the domed closed end covers the exposed stud thread, preventing contact between the stud tip and the corrosive process environment and eliminating thread damage on the exposed end. Exotic alloy dome nuts for visible connections in chemical plant, food processing equipment, and pharmaceutical vessels where end-thread corrosion or hygiene is a concern. M6–M36.
Prevailing Torque Nuts
All-metal prevailing torque nuts (deformed thread or elliptical thread type) that resist loosening under vibration without requiring additional locking mechanisms. For vibrating chemical plant, agitated vessel connections, and pump body bolting in exotic alloy service where nylon insert lock nuts are incompatible with elevated temperature or corrosive environment. M6–M64 in stainless and exotic alloys.
Custom Nuts
Non-standard AF dimensions, left-hand thread, fine pitch, inch UNC/UNF thread, T-slot nuts, weld nuts, and drawing-specific configurations in any exotic alloy. For proprietary pressure vessel designs, specialised acid plant equipment, and all applications where standard DIN/ASME dimensions do not apply. Email drawing to sales@akbarfasteners.in.
Heavy Hex & Std Hex Nut Dimensions M12–M100
Heavy hex (ASME B18.2.2) and standard hex (DIN 934 / ISO 4032) dimensions in mm. Inch-thread dimensions and coupling nut DIN 6334 on request to sales@akbarfasteners.in.
| Size (M) | Pitch | Std Hex AF mm | Std Ht (m) mm | Heavy Hex AF mm | Heavy Hex Ht mm | Coupling L mm | Condition |
|---|---|---|---|---|---|---|---|
| ASME B18.2.2 HEAVY HEX · DIN 934 STD HEX · UNS EXOTIC ALLOY · ASTM-CERTIFIED BAR · PMI VERIFIED | |||||||
| M12 | 1.75 mm | 19.0 | 10.8 | 21.0 | 11.1 | ~36 | Sol. Ann. / As spec. |
| M16 | 2.0 mm | 24.0 | 14.8 | 26.9 | 15.9 | ~48 | Sol. Ann. / As spec. |
| M20 | 2.5 mm | 30.0 | 18.0 | 33.5 | 19.8 | ~60 | Sol. Ann. / As spec. |
| M24 | 3.0 mm | 36.0 | 21.5 | 40.4 | 23.8 | ~72 | Sol. Ann. / As spec. |
| M30 | 3.5 mm | 46.0 | 25.6 | 50.8 | 28.6 | ~90 | Sol. Ann. / As spec. |
| M36 | 4.0 mm | 55.0 | 31.0 | 60.3 | 34.9 | ~108 | Sol. Ann. / As spec. |
| M42 | 4.5 mm | 65.0 | 34.0 | 71.0 | 38.1 | ~126 | Sol. Ann. / As spec. |
| M48 | 5.0 mm | 75.0 | 38.0 | 82.6 | 42.9 | ~144 | Sol. Ann. / As spec. |
| M56–M100 | Custom | Custom | Custom | Custom | Custom | Custom | As spec. |
Inch UNC/UNF, fine pitch, and coupling nut DIN 6334 dimensions on request. sales@akbarfasteners.in
Exotic Alloy Nuts — Complete Material Range
All exotic and engineering alloys available as nuts in all types. Heavy hex nuts matched from same heat as stud bolts — single MTC for the complete stud bolt set. Click any card for the alloy-specific page.
Hastelloy C276
Hastelloy C22
Hastelloy B3 / B2
Monel K500
Monel 400
Inconel 625 / 718
Incoloy 825 / 925
Nickel 200 / 201
SS 316L / 904L / 2205 / 2507
A194 2H / 2HM
Titanium Grade 2 / Grade 5
Duplex 2205 / Super Duplex 2507
Nut Applications
Wherever a stud bolt, bolt, or threaded rod is used in a corrosive environment — the nut material is equally critical. Matched-alloy nuts prevent the galvanic corrosion that occurs when dissimilar metals meet in an electrolyte.
Chemical Processing
matched B16.5 stud sets
Oil & Gas
B7M sour service sets
Offshore & FPSO
Class 1500/2500 stud sets
FGD Systems
absorber flange nut sets
Power Generation
steam flange stud sets
Desalination
seawater circuit stud sets
Pharmaceutical
GMP equipment nut sets
Caustic & HF Plant
caustic soda plant nut sets
Nut Standards Coverage
Same ISO 9001:2015 quality system as all fastener types. Full heat traceability from ASTM bar stock to dispatched nut.
Complete Documentation Package
Heat & Lot Traceable
Conformance
100% Lots Verified
Tensile · Hardness
TÜV · BV · Lloyds
Need Exotic Alloy Nuts
Matched to Your Stud Bolts?
Nut type · alloy · size · quantity · matched stud bolt set requirement · documentation. Akbar Fasteners Pvt. Ltd. responds within 24 hours.
Export: +91 8696 32 4646 · Support: +91 800 9315 333 · export@akbarfasteners.in