Silicon Bronze Bolts

Silicon Bronze Bolts

Electrical Accessories India manufactures silicon bronze bolts in hex head, carriage, and other configurations from C65100 and C65500 silicon bronze alloys for critical corrosive and marine electrical service applications. Silicon bronze bolts are the preferred fastener for earthing systems in coastal and offshore substations, marine electrical installations, chemical plant bonding systems, and any high-corrosion environment where standard brass or carbon steel bolts would suffer premature failure. With tensile strength up to 560 MPa, zero dezincification, excellent seawater resistance, and ATEX non-sparking certification, silicon bronze bolts provide a technically superior and long-service-life solution for engineering professionals specifying electrical fasteners in aggressive environments.

Product Overview

Hex Head Silicon Bronze Bolts (DIN 933 / DIN 931)

Silicon bronze hex bolts are produced in full-thread configuration (DIN 933 / ISO 4017) and partial-thread configuration (DIN 931 / ISO 4014) in metric M4–M36 and inch 1/4″–1-1/2″ UNC/UNF. The hex head dimensions conform exactly to the standard DIN/ISO specifications, ensuring interchangeability with standard wrench/socket tooling. Grade: C65500 High Silicon Bronze A (3% Si) for maximum corrosion performance; C65100 Low Silicon Bronze B (1.5% Si) for less demanding applications. Typical tensile strength: C65500 = 490–560 MPa (comparable to Grade 8.8 steel in smaller diameters), making silicon bronze bolts structurally adequate for most panel, enclosure, and electrical hardware assembly loads.

Silicon Bronze Carriage Bolts (Coach Bolts)

Silicon bronze carriage bolts (DIN 603 profile: round dome head with square neck) are used for wood pole and timber structure mounting of earthing conductors, lighting protection hardware, bonding conductors for offshore jetty structures, wooden boat hull bonding connections, and marine timber electrical installations. Available M6 to M20 in lengths 20–200 mm. The square neck prevents rotation during tightening, allowing single-person installation. Carriage bolt thread is coarse (ISO Metric Coarse) for timber holding strength.

Silicon Bronze Eye Bolts for Electrical Applications

Standard DIN 580 silicon bronze eye bolts are stocked in M8–M20 for lifting and cable strain relief applications in marine and outdoor electrical installations. Custom silicon bronze eye bolts with reduced shank diameter, extended thread, or closed forged eye are manufactured to customer drawings. For transformer bushing applications, see our dedicated Aluminium Bronze Eye Bolts for Transformer Bushings product page.

Threaded Stud Bolts in Silicon Bronze

Silicon bronze stud bolts (threaded both ends, unthreaded centre shank, per DIN 939 / DIN 938) are produced in M6–M30 for flange connections in chemical plant pipework, electrical enclosure flanges, equipment base mounting, and earthing bus stud connections. Available with equal thread both ends (DIN 938) or different thread lengths (DIN 939 – longer end for equipment mounting in tapped hole). For stud bolts with full thread (all-thread rod), see Silicon Bronze Studs.

Square Head and T-Head Silicon Bronze Bolts

Square head silicon bronze bolts are manufactured for foundation and anchor bolt applications in chemical plant structures, substation foundations, and outdoor electrical equipment mounting where concrete embedment or timber seat grip is required. T-head bolts are used in channel and cable tray mounting systems. Custom embedded anchor bolts with hook, L-bend, or J-bend configurations in silicon bronze are also produced for specialist civil-electrical interface applications.

Silicon Bronze U-Bolts and Special Forms

Silicon bronze U-bolts are manufactured for cable tray support clamps, pipe bonding straps, cable lashing clamps, and earthing cable routing hardware in corrosive marine and offshore environments. U-bolt thread ends: M8–M16 (nut-tightened). Standard semicircular and square-bend forms. Pipe-clamp silicon bronze sets (U-bolt + saddle plate + 2 nuts) supplied as kits for offshore and coastal substation cable management. Custom special-form silicon bronze bolts (hook bolts, J-bolts, foundation anchor bolts) manufactured to drawing.

Hex Socket (Allen) Silicon Bronze Bolts

Silicon bronze socket head cap screws (DIN 912 / ISO 4762 profile) are available in M4–M20 for high-torque, space-constrained applications in marine equipment enclosures, offshore instrument housings, and precision electrical assembly where flush or recessed mounting is required. Socket drive allows higher torque than slotted equivalents and is accessible in confined spaces. Tensile strength grade: equivalent to ISO 8.8 class for C65500, adequate for most structural electrical assembly loads.

Pricing

Silicon bronze bolts are priced at USD 14.90 per kilogram (EXW Jamnagar, India). MOQ: 10 kg per size. Project BOM pricing available for complete bolt/nut/washer sets.

Key Features

• C65500 (High Si Bronze A, 3% Si) and C65100 (Low Si Bronze B, 1.5% Si) grades
• Tensile strength 490–560 MPa (C65500) – structurally adequate for electrical hardware
• Zero dezincification, excellent seawater and chemical corrosion resistance
• Non-sparking (ATEX Zone 1/2), non-magnetic – suitable for explosive atmosphere installations
• Full thread (DIN 933) and partial thread (DIN 931) hex bolts; M4–M36 metric
• Carriage bolts, eye bolts, stud bolts, U-bolts, socket cap screws in same alloy
• ISO 9001:2015 manufactured; ASTM F468 compliance; EN 10204 3.1 MTR

Corrosion Performance Comparison

In salt spray testing (ASTM B117 neutral salt spray), silicon bronze bolts show no red rust or significant corrosion after 1000+ hours. By comparison, hot-dip galvanised steel bolts typically fail (red rust) in 300–500 hours, and standard brass bolts can dezincify and become brittle in chloride-rich buried or submerged environments within 5–10 years. Silicon bronze bolts maintain structural integrity and corrosion resistance in tropical coastal environments for 25+ years without replacement, making them the lowest-lifecycle-cost option for coastal substation earthing hardware.

Compatibility with Other Materials in Earthing Systems

Silicon bronze bolts are galvanically compatible with: copper conductors and copper bonding tapes (E° ≈ +0.34V), silicon bronze connectors and clamps (same alloy), bronze/gunmetal castings (similar composition), and tin-plated copper busbars. Compatibility issues arise when silicon bronze is in contact with: aluminium (significant galvanic difference, E° ≈ 0.9V differential; use insulating washer), zinc/galvanised steel (avoid direct contact in wet environments), and magnesium alloys. For aluminium busbar systems, use silicon bronze bolts with PTFE or nylon insulating washers.

Application in Coastal Substation Earthing

Coastal and island substations (11kV–220kV) in high-corrosion zones (C4/C5 corrosivity per ISO 9223) require non-ferrous earthing hardware throughout. Silicon bronze bolts are used for: earth mat conductor joint clamps, earth rod coupling bolts, GIS/AIS equipment earth connections, transformer tank earth stud bolts, cable tray earthing bolts, lightning protection conductor joints, and equipment bonding conductors. The use of silicon bronze throughout the earthing system creates a homogeneous galvanic couple, eliminating corrosion-driven resistance increase at bolted earthing joints that occurs with mixed-metal assemblies.

Technical Specifications

Silicon Bronze International Grade Equivalents

Product Variants

Applications in Industry

Manufacturing Process

Silicon bronze bolts are manufactured by hot forging (M10 and above) from silicon bronze rod, or by CNC turning + thread rolling for smaller diameters (M4–M10). Hot forging at 700–850°C shapes the hex head, followed by trimming, straightening, and annealing (optional, for ductility). Thread rolling produces cold-worked flanks with better fatigue resistance than cut threads. For longer bolts above M20 × 200 mm, the shank may be produced by turning from hexagonal bar with minimal material removal. Quality inspection includes tensile test (per ASTM F606), dimensional check (per ISO 3269), and visual/optical inspection for head fill, surface defects, and thread completeness.

Quality Standards and Certifications

Why Choose Electrical Accessories India

• Dedicated silicon bronze fastener capability – widest range from single source in India
• Two grades available (C65100, C65500) for application-matched selection
• Non-sparking ATEX documentation available for explosive atmosphere projects
• Earthing system package supply – bolts, nuts, washers, studs, connectors all in silicon bronze
• USD 14.90/kg competitive pricing; project BOM discounting available
• 25+ year service life in coastal C4/C5 corrosivity environments – lowest lifecycle cost
• ISO 9001:2015 with full traceability and EN 10204 3.1 MTR

Frequently Asked Questions (FAQ)

1. What is the tensile strength of silicon bronze bolts vs steel Grade 8.8?

Silicon bronze C65500 bolts achieve 490–560 MPa UTS, compared to Grade 8.8 steel (800 MPa) and Grade 4.6 steel (400 MPa). Silicon bronze bolts are not a substitute for Grade 8.8 in high-load structural applications, but are fully adequate for electrical hardware, earthing connections, panel assembly, and cable gland clamping loads typically encountered in electrical installations.

2. Are silicon bronze bolts suitable for buried earthing systems?

Yes. C65500 silicon bronze bolts are suitable for buried earthing systems in all soil types including aggressive acidic, chloride, and sulphate soils. They are immune to dezincification and SCC in buried conditions. For direct concrete embedment, confirm alkalinity compatibility.

3. What is the price of silicon bronze bolts?

USD 14.90 per kilogram (EXW Jamnagar, India). This represents excellent value given the 25+ year service life compared to galvanised steel bolts requiring periodic replacement in coastal environments.

4. Can silicon bronze bolts be supplied as pre-assembled sets with nuts and washers?

Yes. Bolt + hex nut + flat washer + spring washer sets in silicon bronze are supplied as kits. This ensures galvanic compatibility of all components and simplifies installation. Contact us for kit pricing.

5. Do silicon bronze bolts require a specific torque value for earthing connections?

Torque values depend on bolt diameter and joint configuration. For M12 C65500 silicon bronze bolts at earthing bus connections: typical tightening torque 35–50 Nm. Always refer to IEC 62305 or IS 3043 for earthing joint preparation and clamping force requirements.

6. Are silicon bronze bolts available with hot-dip galvanised nuts?

We do not recommend mixed silicon bronze bolt with galvanised steel nut as this creates a galvanic couple. For systems requiring silicon bronze bolts, use matching silicon bronze or copper alloy nuts throughout. We supply matched sets.

7. What certifications do you provide for silicon bronze bolts used in offshore projects?

We provide: EN 10204 3.1 Material Test Certificate (chemical analysis + mechanical properties), dimensional inspection report, ATEX non-sparking material declaration, REACH/RoHS compliance declaration, and Certificate of Origin for import clearance.

8. What is the lead time for silicon bronze bolts?

Standard sizes (M8–M20, DIN 933/931) typically available from stock within 1–2 weeks. Larger sizes (M24–M36) and special configurations: 3–5 weeks. Project quantities above 500 kg: 4–6 weeks. Contact us early for project planning and material reservation.

Equivalent Terms and Multilingual Reference

Related Products and Linked Terms

• Silicon Bronze Hex Nuts
• Silicon Bronze Flanged Nuts
• Silicon Bronze Hex Flanged Bolts
• Silicon Bronze Studs
• Copper Bolts, Copper Hex Set Screws
• Aluminum Bronze Eye Bolts (Transformer Bushings)
• Silicon bronze washers, silicon bronze flat washers, bronze earthing clamps, non-sparking bolts, marine-grade fasteners

Request a Quote

Contact Electrical Accessories India for silicon bronze bolts for marine, offshore, coastal substation, and chemical plant electrical applications. Pricing: USD 14.90 per kilogram (EXW Jamnagar, India). Full project BOM supply capability.

Email: info@elecaccs.com | Location: Jamnagar, Gujarat, India

Related Parts

Aluminum Bronze Eye Bolts (for Transformer Bushings)

Brass DIN 934 Hex Nuts

Brass Machine Screws

Brass Panel Nuts

Brass Thumb Screws

Copper Bolts, Copper Hex Set Screws

Silicon Bronze Flanged Nuts

Silicon Bronze Hex Flanged Bolts

Silicon Bronze Hex Nuts

Silicon Bronze Studs

Spacers Brass

Standoffs Brass