Gunmetal Castings & 85-5-5-5 Bronze Alloy Castings — Manufacturer & Exporter from India
Brass Parts India is a premier manufacturer and exporter of Gunmetal Castings and 85-5-5-5 Bronze Alloy Castings (also known as LG2 or Leaded Gunmetal), supplying high-quality, traceable castings to industries across the USA, UK, Germany, Australia, Canada, and the Middle East. With over three decades of foundry experience, we produce gunmetal and 85-5-5-5 bronze castings that deliver outstanding corrosion resistance, excellent machinability, pressure tightness, and reliable long-term performance in critical fluid handling, valve, pump, marine, and potable water applications.
Gunmetal — the traditional workhorse of the non-ferrous foundry industry — remains the material of choice for pressure-bearing castings that must perform reliably in both freshwater and seawater environments, making it indispensable for water supply infrastructure, marine engineering, and industrial valve manufacturing worldwide.
What is Gunmetal / 85-5-5-5 Bronze?
Gunmetal is a tin bronze alloy containing copper (approximately 85%), tin (5%), zinc (5%), and lead (5%) — hence the popular designation “85-5-5-5.” This balanced composition gives gunmetal an excellent combination of mechanical strength, corrosion resistance, castability, and machinability. The lead content provides free-machining characteristics and improves pressure tightness by filling micro-shrinkage voids during solidification — making gunmetal castings inherently leakproof for fluid service applications. The absence of aluminum makes gunmetal safe for potable water applications in many international standards.
In the UK it is standardised as LG2 (BS 1400), in the USA as C83600 (ASTM), and in Germany as CuSn5Zn5Pb5 (DIN). It is one of the most widely specified bronze alloys globally for valves, fittings, pump bodies, and water distribution components.
Material Grades & International Equivalents
| Standard | Designation | Cu% | Sn% | Zn% | Pb% | Typical Use |
|---|---|---|---|---|---|---|
| ASTM B62 / CDA C83600 | Ounce Metal / 85-5-5-5 | 84–86 | 4–6 | 4–6 | 4–6 | General purpose valves, fittings, pump bodies |
| BS 1400 LG2 | Leaded Gunmetal 2 | 85–87 | 4.5–6 | 3.5–5.5 | 3–5 | Water valves, marine fittings, pressure castings |
| BS 1400 LG4 | Leaded Gunmetal 4 | 84–86 | 7–9 | 1–3 | 3–5 | High-pressure steam fittings, hydraulic castings |
| DIN 1705 CuSn5Zn5Pb5 | Rotguss RG5 | 84–86 | 4–6 | 4–6 | 4–6 | European standard valves and fittings |
| IS 318 Grade 1 | Gunmetal Grade 1 | 85–88 | 5–7 | 2–5 | 2–5 | Indian standard general purpose |
| JIS H 5111 BC6 | Bronze Casting 6 | 82–87 | 4–7 | 2–7 | 2–7 | Japanese standard for hydraulic castings |
Size & Dimensional Capabilities
| Parameter | Capability |
|---|---|
| Casting Weight | 0.2 kg to 800 kg per piece |
| Maximum Dimensions | Up to 1500 mm in diameter / length |
| Wall Thickness | Minimum 3 mm |
| Surface Finish (as-cast) | Ra 6.3–12.5 µm |
| Machining Tolerance | ±0.05 mm (after CNC finishing) |
| Pressure Test | Up to 25 bar (hydrostatic), higher on request |
| MOQ | 5 pieces (prototypes welcome) |
Key Applications
Gunmetal / 85-5-5-5 castings are the foundation of the global valve and fittings industry. Our castings are used in gate valves, globe valves, ball valves, check valves, and butterfly valves for water supply, heating, and gas systems. In the marine industry, they serve as seacocks, through-hull fittings, bilge pump bodies, and deck fittings. For the oil and gas sector, gunmetal is used in instrument valve bodies, manifold blocks, and flow control components. In potable water infrastructure, gunmetal castings are approved for contact with drinking water under WRAS (UK), NSF/ANSI 61 (USA), and similar standards. Additionally, gunmetal is used in fire protection system fittings, steam traps, boiler fittings, and general industrial pipe fittings.
Performance Metrics
| Property | C83600 / LG2 | LG4 |
|---|---|---|
| Tensile Strength | 240 MPa min | 270 MPa min |
| Yield Strength (0.2%) | 115 MPa min | 130 MPa min |
| Elongation | 20% min | 16% min |
| Hardness (Brinell) | 60–80 HB | 70–90 HB |
| Pressure Tightness | Excellent (leaded microstructure) | Excellent |
| Machinability Rating | 90% (vs. free-cutting brass = 100%) | 85% |
| Max Service Temperature | 260°C (steam service) | 290°C |
Our Technical Expertise
Brass Parts India has been casting gunmetal and leaded bronze alloys for over 30 years, serving valve manufacturers, shipbuilders, water authorities, and engineering companies on every continent. Our in-house capabilities include spectrometric alloy analysis, hydrostatic pressure testing up to 25 bar, full dimensional inspection, and a range of NDT services. We maintain detailed process control records for every heat, enabling full traceability from raw material to finished casting.
Our engineers are experienced in designing gunmetal castings for optimal pressure tightness and machinability — two of the most critical requirements for valve and pump body castings. We work closely with valve manufacturers to develop casting designs that meet wall thickness requirements of relevant standards such as BS EN 1074, API 600, and AWWA C500.
Why Choose Brass Parts India for Gunmetal Castings?
Proven Track Record with Global Valve Manufacturers: We have been supplying gunmetal castings to valve manufacturers in the UK, USA, Germany, and Australia for decades. Our consistent quality and on-time delivery have made us a preferred source for many OEMs who have audited our facility and approved our processes.
Pressure-Tight Castings Guaranteed: Our 85-5-5-5 bronze castings are produced with lead contents precisely controlled to ensure pressure tightness. Every casting intended for pressure service is hydrostatically tested as standard.
Potable Water Approval Support: We can supply castings with chemistry conforming to WRAS, NSF/ANSI 61, and KTW/W270 (Germany) requirements for drinking water contact. Documentation and compliance support are provided.
Global Communication in Your Time Zone: Our sales and technical team is responsive across US, European, and Australian business hours. We respond to all enquiries within 24 hours and provide proactive shipment updates.
What Separates Us from Other Manufacturers
Our integrated foundry-to-finish approach means that gunmetal castings pass through alloy verification, pattern production, moulding, melting, casting, cleaning, pressure testing, machining, and quality inspection — all under one roof. This eliminates vendor chain risks, ensures batch traceability, and gives you a single, accountable partner for your casting supply.
Our Flexibility to Customise Parts
We regularly produce non-standard alloy variants — including low-lead or lead-free gunmetal grades for environmental compliance — and accommodate customer-specific chemical composition limits. We can also apply post-cast treatments such as annealing, sand blasting, shot peening, or special primer coatings, and can machine castings to finished dimensions with threaded ports, drilled holes, or machined flanges ready for assembly.
Customer Testimonials
“We have sourced LG2 gunmetal castings from Brass Parts India for our range of industrial gate valves for over a decade. The pressure-tightness record is exceptional — we have had virtually zero leakers across tens of thousands of pieces. Their communication and documentation are first rate. A truly professional supplier.”
— Michael Thornton, Supply Chain Director, Birmingham, England, UK
“Brass Parts India is our go-to foundry for gunmetal valve bodies. Their C83600 castings consistently meet ASTM B62 chemistry and mechanical requirements. The team is knowledgeable, responsive, and always willing to accommodate our scheduling changes. We recommend them without reservation.”
— Patricia Nguyen, Materials Engineer, Melbourne, Victoria, Australia
Frequently Asked Questions (Q&A)
Q1. What does 85-5-5-5 mean in gunmetal alloy?
It refers to the approximate composition: 85% copper, 5% tin, 5% zinc, and 5% lead. This balanced formulation gives gunmetal its characteristic combination of corrosion resistance, pressure tightness, castability, and excellent machinability.
Q2. Is gunmetal (LG2 / C83600) approved for potable water use?
Yes. Gunmetal castings with lead content conforming to WRAS (UK), NSF/ANSI 61 (USA), and similar standards are approved for contact with drinking water. We can provide castings with reduced lead variants (e.g., 0.25% max Pb) for low-lead drinking water compliance.
Q3. What is the difference between LG2 and LG4 gunmetal?
LG2 (C83600) contains approximately 5% tin and 5% lead and is a general-purpose gunmetal for water, marine, and steam applications. LG4 has higher tin content (7–9%), higher strength, and is preferred for high-pressure steam and hydraulic service. LG2 is more commonly specified globally.
Q4. Can you hydrostatically test gunmetal valve body castings?
Yes. We can test castings at pressures up to 25 bar as standard and higher by arrangement. Test reports are provided as part of the quality documentation package.
Q5. Do you produce centrifugal gunmetal castings as well as sand castings?
Yes. For cylindrical forms such as bushings, liners, sleeves, and pipe flanges, centrifugal casting is often the preferred process as it produces a denser, more uniform microstructure with better mechanical properties than static sand casting.
Q6. What standards govern gunmetal castings?
Key standards include ASTM B62 (USA), BS 1400 LG2/LG4 (UK), DIN 1705 (Germany), IS 318 (India), and JIS H 5111 (Japan). We can cast to any of these standards and provide corresponding certifications.
Q7. Can you reproduce valve body castings from a sample?
Yes. We can measure a physical sample, create a casting drawing, develop a pattern, and reproduce the part. We often improve the design for better castability and machinability during this process.
Q8. Do you offer complete machined valve bodies, ready for assembly?
Yes. Our in-house CNC machining facility can produce fully machined valve bodies with all ports, bores, seat faces, and threaded connections machined to drawing — delivered ready for valve assembly.
Q9. What is the maximum pressure rating for gunmetal castings?
This depends on wall thickness and design, but standard PN16 (16 bar) rated valve bodies in gunmetal are common. Special designs for PN25 (25 bar) and higher are possible with appropriate wall thicknesses and design reviews.
Q10. Is lead-free gunmetal available?
Yes. We can supply low-lead (Pb ≤ 0.25%) or lead-free variants such as CDA C89520 (silicon brass) or similar eco-brass alloys for jurisdictions requiring low lead content in plumbing products — including California Prop 65 and EU Directive compliance.
Q11. What is the difference between gunmetal and ordinary brass?
Gunmetal contains tin, which imparts superior corrosion resistance (particularly in steam and seawater), better hot strength, and pressure tightness. Brass (copper-zinc) is stronger and harder but less corrosion-resistant in saline or steam environments. For valve and pump bodies, gunmetal is generally the preferred choice.
Q12. Do you supply ASTM B62 material test certificates?
Yes. Full MTCs referencing ASTM B62 (or BS 1400 LG2/DIN 1705 as applicable) are provided with every shipment, including chemistry and mechanical test results from our laboratory.
Q13. Can gunmetal castings be used for steam service?
Yes. Gunmetal (particularly LG4) is suitable for steam service up to approximately 260–290°C, depending on alloy grade. It has a long history of use in steam valves, steam traps, and boiler fittings in marine and industrial applications.
Q14. What is your turnaround time for gunmetal sand castings?
For repeat orders with existing patterns, we can typically ship within 3–4 weeks of order confirmation. New part development (including pattern making) takes 5–8 weeks for first articles.
Q15. Do you offer consignment stocking for large volume customers?
Yes. For customers with stable, predictable consumption, we can manufacture against a quarterly or annual forecast and hold stock at our facility for call-off delivery, reducing your procurement lead times to near-zero.
Export-Worthy Packaging
Gunmetal castings are packed in moisture-proof VCI poly bags, placed in foam-cushioned cardboard cartons or wooden crates, and sealed with export-grade banding. All packages are clearly labelled with heat number, alloy grade, customer PO number, weight, and destination details. Full export documentation — commercial invoice, packing list, MTC, and COA — is prepared as standard. Sea-worthy and air-worthy packing options are available depending on shipment urgency.
Glossary of Related Terms
LG2: British Standard designation for 85-5-5-5 Leaded Gunmetal (BS 1400), equivalent to ASTM C83600. The most widely used casting bronze for valves and water fittings.
Rotguss (RG5): German (DIN) term for gunmetal, literally “red cast” — referring to the reddish colour of the alloy. RG5 corresponds to CuSn5Zn5Pb5.
Pressure Tightness: The ability of a casting to hold pressure without leaking. Critical for valve bodies, pump casings, and hydraulic components. The lead phase in gunmetal improves pressure tightness by filling micro-porosity.
Dezincification Resistance: Gunmetal contains relatively low zinc (5%), making it inherently resistant to dezincification — the selective corrosion of zinc from copper-zinc alloys in aggressive water conditions.
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Call to Action
Need reliable Gunmetal / 85-5-5-5 Bronze Alloy Castings from an experienced Indian foundry with decades of global export experience? Contact Brass Parts India today for a quick technical review and competitive quotation. We respond within 24 hours.
📧 Email: sales@brass-parts-india.com
📞 Phone / WhatsApp: +91 22 43 44 9300
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