Distribution Range · Vetted Partner Mills · Ahmedabad
Hex Bolts and Nuts Manufacturer & Wholesale Supply
Metric hex head bolts, companion hex nuts, and hardened washers supplied across Property Classes 4.6, 8.8, 10.9, and austenitic stainless steel. Distributed from vetted partner mills in Ahmedabad with full MTC EN 10204 3.1 pass-through and lot traceability.
Overview: hex fastener scope & consolidated procurement model
Hexagon head bolts and companion hex nuts constitute the mechanical backbone of industrial structural connections and mechanical assemblies worldwide. Whether joining structural steel rafter trusses, assembling heavy industrial machinery, or bolting high-pressure pipeline flanges, the combination of a precision-threaded hex bolt and matching proof-stress nut ensures predictable joint clamping without slip.
KP Fasteners provides complete commercial coverage across full-thread screws (DIN 933 / ISO 4017), partial-thread shear bolts (DIN 931 / ISO 4014), standard nuts (DIN 934), heavy hex structural nuts (ASME B18.2.2 / ASTM A194 2H), thin lock nuts (DIN 439), and prevailing-torque nylock nuts (DIN 985). We distribute these items in mild steel (Property Classes 4.6 and 4.8), high-tensile carbon steel (Property Classes 8.8 and 10.9), and austenitic stainless steel (SS 304 and SS 316).
Transparency is fundamental to our supply model: KP Fasteners distributes commodity hex bolts and nuts through vetted, audit-verified partner primary mills. This distribution range directly complements our dedicated in-house manufacturing lines in Ahmedabad, where we manufacture foundation bolts for PEB column base plates, stud bolts for flange joints, and specialized sag rods.
By purchasing both custom anchorage items and high-volume standard hex hardware through KP Fasteners, engineering procurement teams eliminate fragmented vendor management, guarantee compatible hot-dip galvanized thread fitments, and consolidate their complete fastener schedule onto a single commercial purchase order.
Standards cross-reference: DIN vs ISO vs IS vs ASTM
Engineering drawings across Indian and international EPC projects frequently reference equivalent German (DIN), International (ISO), Indian (IS), and American (ASTM) standards. The matrix below clarifies corresponding dimensional and mechanical specifications:
| DIN Standard | ISO Equivalent | Indian Standard (BIS) | Engineering Description & Fastener Geometry |
|---|---|---|---|
| DIN 931 | ISO 4014 | IS 1364 (Part 1) | Hexagon head bolt with partial thread (plain unthreaded shank) |
| DIN 933 | ISO 4017 | IS 1363 (Part 1) | Hexagon head screw with full thread from under head to tip |
| DIN 934 | ISO 4032 | IS 1363 (Part 3) | Standard hexagon nut with nominal height of 0.8d |
| DIN 439 | ISO 4035 | IS 1364 (Part 3) | Hexagon thin / jam nut with nominal height of 0.5d for lock assemblies |
| DIN 985 | ISO 7040 | IS 7002 | Prevailing torque hexagon lock nut with non-metallic nylon insert |
| DIN 6914 | ISO 7412 | IS 6639 | High-strength heavy hexagon head bolt for structural steel friction joints |
| DIN 6921 | EN 1665 | IS 1367 | Hexagon bolt with serrated or smooth integrated bearing flange |
| DIN 6923 | ISO 4161 | IS 1367 | Hexagon nut with serrated or smooth integrated bearing flange |
| ASTM A307 | - | IS 1367 Gr 4.6 | Low-carbon steel externally threaded standard fasteners (60 ksi tensile) |
| ASTM A325 | ISO 7412 (overlap) | IS 6639 / 8.8S | High-strength structural bolts for structural steel joints (120 ksi tensile) |
| ASTM A490 | - | IS 6639 / 10.9S | Heat-treated alloy steel structural bolts for dynamic framing (150 ksi tensile) |
| ISO 898-1 | - | IS 1367 (Part 3) | Mechanical properties of carbon and alloy steel externally threaded bolts |
| ISO 3506-1 | - | IS 1367 (Part 14) | Mechanical properties of corrosion-resistant stainless steel fasteners (A2/A4) |
Hex bolt specification schedule (M6 to M64)
Standard diameter ranges, length offerings, governing specifications, and typical industrial applications across externally threaded hex fasteners:
| Nominal Size Range | Length Range | Available Property Classes | Governing Standards | Standard Surface Coatings | Primary Industrial Application |
|---|---|---|---|---|---|
| M6 - M12 | 16 - 100 mm | Class 4.6, 8.8, SS 304 | DIN 933 (full) / DIN 931 (part) | Clear Zinc, Yellow Zinc, Natural SS | Light machinery, electrical brackets, solar rail sub-assembly |
| M14 - M20 | 25 - 180 mm | Class 8.8, 10.9, SS 316 | DIN 931 / DIN 933 / ISO 4014 | Hot-Dip Galvanized, Zinc, Black Oxide | PEB rafter connections, column base framing, automotive tier joints |
| M22 - M30 | 40 - 260 mm | Class 8.8, 10.9 | DIN 931 / ISO 4014 / IS 1364 | HDG (ISO 1461), Mechanical Zinc | Heavy structural steel moments, crane girders, industrial machinery bases |
| M33 - M42 | 60 - 350 mm | Class 8.8, 10.9 | ISO 4014 / DIN 931 | Hot-Dip Galvanized, Self-Colour | Bridge girder connections, heavy plant equipment, vibrating screens |
| M48 - M64 | 80 - 500 mm | Class 8.8, 10.9 | ISO 4014 / DIN 931 | Hot-Dip Galvanized, Black Phosphated | Power plant turbine skids, mining crusher frames, heavy foundations |
| 1/2" - 1-1/2" | 1-1/2" - 8" | ASTM A325 (Type 1) | ASTM A325 / ASME B18.2.6 | Hot-Dip Galvanized (ASTM A153) | High-strength structural steel connections requiring heavy hex geometry |
| 1/2" - 1-1/2" | 2" - 8" | ASTM A490 (Type 1) | ASTM A490 / ASME B18.2.6 | Chemical Black Oxide with Oil | High-load dynamic and seismic framing (HDG prohibited due to HDE) |
| M6 - M24 (SS 304) | 16 - 200 mm | A2-70 (700 MPa UTS) | DIN 933 / DIN 931 / ISO 4017 | Chemical Passivated (ASTM A967) | Food & beverage processing, cleanroom equipment, architectural facade |
| M6 - M24 (SS 316) | 16 - 200 mm | A4-70 (700 MPa UTS) | DIN 933 / DIN 931 / ISO 4017 | Chemical Passivated (ASTM A967) | Marine and coastal solar, chemical processing plants, water-retaining tanks |
Hex nut family specification schedule
Internal thread specifications, property class ratings, and functional mechanical roles across standard, heavy, thin, and locking hex nut geometries:
| Nut Family & Style | Governing Standards | Property Class / Material | Thread Diameter Range | Surface Finishes | Mechanical Function & Joint Pairing |
|---|---|---|---|---|---|
| Standard Metric Hex Nut | DIN 934 / ISO 4032 / IS 1363 Pt 3 | Class 8, 10, SS 304, SS 316 | M6 - M64 | Zinc Plated, HDG, Passivated | Standard structural and mechanical pairing matching mating bolt proof stress |
| Heavy Hex Structural Nut | ASME B18.2.2 / ASTM A194 2H / A563 | Grade 2H, Grade DH, Class 10 | 1/2" - 2-1/2" (M16 - M64) | Hot-Dip Galvanized, Black Oxide | High-strength friction grip joints paired with ASTM A325/A490 and A193 B7 studs |
| Prevailing Torque Nylock Nut | DIN 985 / ISO 7040 / IS 7002 | Class 8, 10, SS 304 | M6 - M36 | Zinc Trivalent, Natural Stainless | Self-locking vibration resistance for automotive chassis and vibrating equipment |
| Hex Thin / Jam Lock Nut | DIN 439 / ISO 4035 / IS 1364 Pt 3 | Class 04, 05, SS 304 | M8 - M48 | Zinc Plated, Self-Colour, SS | 0.5d thin profile used as secondary lock nut or in tight axial clearances |
| Serrated Hex Flange Nut | DIN 6923 / ISO 4161 / EN 1661 | Class 8, 10 | M6 - M20 | Zinc Plated, Geomet, HDG | Spreads load and resists loosening without requiring a separate flat washer |
| Acorn / Dome Cap Nut | DIN 1587 | Class 6, SS 304, Brass | M6 - M24 | Bright Chrome, Nickel, Passivated | Encloses thread ends to prevent snagging injuries and seal against moisture ingress |
Product variant matrix: grade × coating × size availability
Stocking matrix summarizing standard diameters, lengths, protective surface barriers, and mechanical property grades:
| Property Class / Grade | Diameter Range | Standard Length Range | Default Surface Coatings | Typical Application Scope |
|---|---|---|---|---|
| Property Class 4.6 / 4.8 | M4 - M30 | 10 - 300 mm | Clear Zinc Electroplate (Cr3+), Self-Colour Black MS | General commercial engineering, non-structural covers, light brackets |
| Property Class 8.8 | M6 - M48 | 20 - 500 mm | Hot-Dip Galvanized (ISO 1461), Zinc Yellow Trivalent, Black Oxide | PEB steel framing, civil construction, machinery frames, solar structures |
| Property Class 10.9 | M8 - M36 | 20 - 400 mm | Mechanical Zinc, Zinc-Nickel, HDG with mandatory 200 °C bake-out | Automotive tier chassis, dynamic shear joints, heavy earth-moving equipment |
| Property Class 12.9 | M8 - M30 | 25 - 250 mm | Chemical Black Oxide with rust-preventive oil (HDG strictly prohibited) | High-stress machine tools, plastic injection molds, hydraulic cylinder joints |
| Stainless Steel 304 (A2-70) | M4 - M24 | 10 - 200 mm | Acid Cleaned & Passivated per ASTM A967 | Food processing machinery, architectural brackets, inland solar MMS |
| Stainless Steel 316 (A4-70) | M4 - M24 | 10 - 200 mm | Acid Cleaned & Passivated per ASTM A967 | Chemical process plants, coastal solar installations, marine hardware |
Decision guide: property-class selection & coating engineering
Selecting the correct fastener grade is determined by joint stress dynamics. Property Class 4.6 is suitable strictly for low-stress commercial assemblies and sheet metal brackets where tensile forces remain below 400 MPa. For structural steel framing and pre-engineered buildings (PEB), Property Class 8.8 is the mandatory baseline, offering 800 MPa minimum tensile strength and 640 MPa yield strength to withstand wind and dead loads.
For heavy machinery, automotive chassis mounts, and dynamic cyclic loads, Property Class 10.9 provides superior shear resistance (1040 MPa tensile). Explore our dedicated property class 8.8 / 10.9 decision guide for comprehensive tensile and proof-load property charts.
Surface coating selection requires balancing atmospheric corrosion protection against hydrogen embrittlement (HDE) risks per ISO 898-1 §9.6. Hot-dip galvanizing (HDG) per ISO 1461 provides exceptional 85 µm sacrificial zinc protection for outdoor Class 8.8 structural connections. However, mating nuts must be tapped oversize (thread tolerance 6AZ or 6AX) after galvanizing to accommodate zinc build-up on bolt threads.
On high-strength Class 10.9 fasteners, acid pickling and molten zinc baths can introduce atomic hydrogen into grain boundaries, risking sudden delayed brittle fracture. Therefore, we recommend mechanical galvanizing or zinc-nickel coatings for Class 10.9 components, while Class 12.9 is supplied in chemical black oxide only.
| Application Environment | Recommended Grade | Recommended Coating | Engineering Design Notes |
|---|---|---|---|
| Light-Duty Machinery Sub-Assembly | Property Class 4.6 / 4.8 | Trivalent Zinc Electroplate | Economical standard for indoor non-vibrating covers and low-stress brackets. |
| PEB Column & Rafter Connections | Property Class 8.8 High-Tensile | Hot-Dip Galvanized (ISO 1461) | Standard structural steel workhorse; must pair with HDG Class 8 overtapped nuts. |
| Heavy Equipment & Compressor Mounts | Property Class 8.8 or 10.9 | Zinc + DIN 985 Nylock Nut | High cyclic vibration; nylock or prevailing torque nut prevents back-off. |
| Inland Solar MMS Sub-Assembly | Property Class 8.8 HDG or SS 304 | Hot-Dip Galvanized / Passivated | HDG for steel substructure; SS 304 for module side to prevent galvanic attack. |
| Coastal Solar & Marine Structures | Stainless Steel 316 (A4-70) | Natural Passivated | Molybdenum-bearing 316 prevents severe chloride pitting within 5 km of sea. |
| Structural Steel Friction Joints (A325) | Class 8.8S / ASTM A325 | Hot-Dip Galvanized (ASTM A153) | Requires ASTM A194 2H or A563 heavy hex nuts and hardened flat washers. |
| Food, Dairy & Cleanroom Machinery | Stainless Steel 304 or 316 | Passivated per ASTM A967 | Non-contaminating passive surface; resists frequent sanitary washdowns. |
| High-Cycle Dynamic / Seismic Framing | Property Class 10.9 | Mechanical Zinc / Geomet Flake | Non-electrolytic coating eliminates catastrophic hydrogen embrittlement risks. |
| High-Stress Tool-and-Die Fixtures | Property Class 12.9 | Chemical Black Oxide with Oil | Provides maximum 1220 MPa tensile strength while maintaining class 6g thread fit. |
Applications & industries supplied across India
KP Fasteners routinely quotes and distributes standard hex head fasteners across primary infrastructure and manufacturing sectors:
Pre-Engineered Buildings & Structural Steel
High-volume Class 8.8 HDG hex head bolts, nuts, and washers for primary rafter-to-column connections, moment joints, and cold-formed secondary framing.
Industrial Machinery & Equipment
Class 8.8 and 10.9 zinc-plated hex bolts paired with DIN 985 nylock nuts for heavy pumps, industrial gearboxes, stamping presses, and electric motor mounts.
Commercial Vehicles & Heavy Trailers
High-tensile Class 10.9 flange bolts and prevailing-torque lock nuts for automotive tier-2 chassis frames, axle suspensions, and fifth-wheel assemblies.
Solar Structure Sub-Assembly
SS 304 and HDG Class 8.8 hex sets for solar mounting structure framing, diagonal braces, and purlin attachments in rooftop and ground-mount arrays.
Process Piping & Flange Assemblies
ASTM A194 Grade 2H heavy hex nuts and ASTM A193 B7 stud combinations for high-temperature and high-pressure ASME B16.5 pipeline flanges.
Hardware Wholesalers & Jobbing Shops
Consolidated bulk supply of mixed metric diameters and lengths shipped in standard 25 kg bags or wooden crates with full test certificate traceability.
Related structural and industrial fastener lines
Explore dedicated technical catalogs and materials guides to complete your procurement schedule:
High-Tensile Fasteners Guide
Comprehensive metallurgical comparison of Property Classes 8.8, 10.9, and 12.9, detailing tensile limits, proof loads, and hydrogen embrittlement avoidance.
property class 8.8 / 10.9 decision guide
Stainless Steel Fasteners Guide
Technical selection guide covering austenitic grades A2-70 and A4-70, PREN pitting resistance, and marine atmospheric performance.
SS 304 vs SS 316 for service environment
Socket Head & CSK Screws
DIN 912 Allen socket head cap screws and DIN 7991 countersunk screws in Class 10.9 and 12.9 for recessed and tight-clearance machine assemblies.
socket head cap screws and countersunk bolts
Construction & Infrastructure Hub
Sector-wide structural procurement guide connecting foundation anchor bolts, PEB sag rods, and structural hex bolts onto consolidated purchase orders.
PEB structural fastener schedules
Automotive & Heavy Engineering Hub
Engineering procurement specifications for tier-2/tier-3 automotive component builders, mining machinery, and agricultural implement manufacturers.
heavy machinery and automotive tier hardware
Custom Fasteners on Drawing
Drawing-based manufacturing for non-standard shoulder bolts, stepped studs, and specialized alloy hardware produced to exact engineering CAD models.
custom specials on drawingFrequently asked questions about hex bolts and nuts
Key engineering answers regarding manufacturing origins, property classes, standards differences, lead times, and structural certifications.
Do you manufacture hex bolts and nuts in-house or source them?
We distribute hex bolts, nuts, and washers from vetted primary partner mills - these are part of our distribution range rather than in-house OEM production. Our in-house manufacturing lines in Ahmedabad focus on custom foundation bolts, stud bolts, and PEB sag rods. Supplying commodity hex fasteners alongside our manufactured lines allows contractors and OEMs to consolidate their structural bill of materials onto a single purchase order with unified dispatch and MTC pass-through.
Which property classes do you routinely stock?
We routinely stock Property Classes 4.6 and 4.8 for light machinery assembly, Property Class 8.8 for structural steel and PEB frameworks, Property Class 10.9 for high-stress automotive and equipment mountings, and austenitic stainless steels SS 304 (A2-70) and SS 316 (A4-70) for corrosive environments. High-strength Class 12.9 socket head bolts and imperial ASTM A325/A490 structural bolts are supplied on confirmed project enquiry.
What is the difference between DIN 931 and DIN 933?
DIN 931 (ISO 4014 equivalent) designates a hexagon head bolt with a partial thread, leaving a smooth unthreaded shank under the head designed to bear heavy shear loads across joined plates. DIN 933 (ISO 4017 equivalent) designates a hexagon head screw threaded fully from under the head to the tip, ideal for tapped blind holes or compact clamping grips. Both standards share identical head dimensions across matching metric diameters.
Can you supply MTC EN 10204 3.1 and what is the typical lead time?
Yes - mill test certificates (MTC EN 10204 3.1) are passed through directly from originating primary manufacturers, detailing heat chemical melt analysis and mechanical proof testing. Standard stocked metric sizes dispatch within 24-72 hours across Ahmedabad and Gujarat, and 3-7 business days pan-India. Custom non-stocked lengths or specialized surface coatings carry a 7-14 day delivery window.
Do you supply ASTM A325 and ASTM A490 structural bolts?
Yes. High-strength structural bolts conforming to ASTM A325 and ASTM A490 (or their metric equivalents ISO 7412 and DIN 6914) are supplied for heavy steel framing, crane girders, and bridge structures. These bolts feature larger head dimensions across flats and must be paired with matching heavy hex nuts (ASTM A194 Grade 2H or ASTM A563 Grade DH) and hardened ASTM F436 structural flat washers.
Request a comprehensive hex bolt & nut BOQ quotation
Submit your fastener schedule, structural engineering drawings, or bulk quantity requirements. Our technical sales desk will verify property classes, confirm coating requirements, and issue an itemized commercial quotation within 24 hours.