85-5-5-5 Gunmetal Bronze Casting – C83600 LG2 Manufacturer from India

85-5-5-5 Gunmetal bronze is one of the most trusted and versatile copper casting alloys in global engineering. Also known as Red Brass, Composition Bronze, LG2, or C83600, this alloy has served engineers and manufacturers for over two centuries in valves, fittings, pumps, marine hardware, and steam piping. Brass & Copper Parts India manufactures precision 85-5-5-5 Gunmetal bronze castings in Jamnagar, India, supplying US valve manufacturers, pump OEMs, marine suppliers, and MRO distributors.

The “85-5-5-5” Composition Explained

The name “85-5-5-5” directly references the nominal percentage composition of the four principal elements:

• 85% Copper (Cu): Provides the primary matrix — excellent corrosion resistance, electrical conductivity, and castability
• 5% Tin (Sn): Strengthens the copper matrix through solid-solution hardening; improves pressure tightness and corrosion resistance in steam and water
• 5% Lead (Pb): Fills micro-shrinkage porosity during solidification, giving the alloy its outstanding pressure tightness; also acts as a free-machining agent (machinability rating: 90%)
• 5% Zinc (Zn): Improves fluidity for casting, enabling complex shapes; enhances strength and reduces cost vs. pure copper

Why 85-5-5-5 Gunmetal Has Remained the Standard for 200+ Years

The longevity of 85-5-5-5 Gunmetal as a premier casting alloy comes from a remarkable balance of properties that no single alternative fully replicates:

• Pressure tightness: Lead-filled microporosity makes C83600 essentially leak-proof in valve bodies, pump casings, and pressure fittings — confirmed by ASTM B62 standard and MSS SP-70 valve body certification
• Machinability: 90% machinability rating (vs. free-cutting brass at 100%) makes post-casting machining economical
• Corrosion resistance: Excellent resistance to potable water, steam, saltwater, and most industrial chemicals at moderate temperatures
• Casting fluidity: Zinc addition improves melt fluidity, enabling complex, thin-walled castings without cold shuts or misruns
• Broad service range: Suitable for water service to 204°C, steam service to 260°C, and pressures to 600 PSI (Class 250)

85-5-5-5 Gunmetal Bronze Castings We Manufacture

Gate Valve Bodies in 85-5-5-5 Gunmetal

Sand cast C83600 gate valve bodies for water, steam, and gas service in Class 125 and Class 250 pressure ratings. Manufactured per ASME B16.15, MSS SP-70, and ASTM B62. Available in 1/4″ to 12″ nominal pipe sizes.

Globe Valve Bodies

85-5-5-5 Gunmetal globe valve bodies for throttling and flow regulation in steam and hot water systems. Pressure tested to 1.5× rated working pressure before machining.

Check Valve Bodies and Swing Disc Castings

Bronze check valve bodies (swing type and lift type) in ANSI Class 125 and 250 for water and steam service. All check valve castings are tested per MSS SP-71.

Bronze Pipe Fittings (ANSI B16.15)

Complete range of sand-cast 85-5-5-5 Gunmetal pipe fittings: elbows (45°, 90°, street), tees, couplings, crosses, caps, reducing bushings, return bends, and locknuts. Available in NPT (National Pipe Thread) and BSP thread forms.

Bronze Pump Casings and Impellers

Centrifugal pump casings, impellers, diffusers, and seal plates cast in 85-5-5-5 Gunmetal for HVAC, water supply, marine bilge, and industrial pump applications. Centrifugal casting available for cylindrical components like bearing housings and seal rings.

Marine Hardware in 85-5-5-5 Gunmetal

Seacocks, through-hull fittings, strainer bodies, propeller shaft seals, and deck hardware cast in C83600 Gunmetal for recreational boating and commercial marine markets. LG2 / C83600 is MIL-B-16541 approved for naval applications.

Mechanical Properties of 85-5-5-5 Gunmetal (C83600/LG2)

Property	Sand Cast	Centrifugal Cast	Standard
Ultimate Tensile Strength	255 MPa (37 ksi)	275 MPa (40 ksi)	ASTM B62
0.2% Yield Strength	117 MPa (17 ksi)	140 MPa (20 ksi)	ASTM B62
Elongation (2″)	30% min.	30% min.	ASTM B62
Brinell Hardness	60–80 HB	70–90 HB	—
Shear Strength	186 MPa	200 MPa	—
Fatigue Strength (10⁸ cycles)	69 MPa	76 MPa	—

85-5-5-5 Gunmetal International Equivalents (Comprehensive)

Standard	Designation	Country	Notes
ASTM B62 / UNS	C83600	USA	Composition Bronze, Red Brass
BS 1400	LG2	UK	Leaded Gunmetal 2
EN 1982	CC491K / CuSn5Pb5Zn5	Europe	—
DIN 1705	RG5 (Rotguss 5)	Germany	Red Casting Alloy
ISO 1338	CuSn5Pb5Zn5	International	ISO designation
JIS H 5111	CAC402	Japan	—
IS 318	Grade 2 Gunmetal	India	—
MIL-B-16541	Alloy B	USA (Military)	Naval grade approval
ASME B16.15	—	USA	Cast bronze pipe fittings std.

Why Choose Brass & Copper Parts India for 85-5-5-5 Gunmetal Castings?

• ASTM B62 certified: Full chemical analysis and mechanical testing with every casting batch
• Pressure testing: Hydrostatic and pneumatic testing on all pressure-rated castings
• Multiple casting routes: Sand, centrifugal, and investment casting for optimal economics by part size
• CNC machining: Complete cast-and-machine supply; no secondary vendor needed
• ASME/ANSI compliance: Valve and fitting designs reviewed by our engineers for standard compliance
• US MRO stock programs: Quarterly blanket orders with consignment stock available
• 25+ years of export experience: Dedicated logistics team for US port deliveries
• Pricing advantage: 35–50% lower than equivalent US or European castings

Frequently Asked Questions — 85-5-5-5 Gunmetal Bronze Casting

Q1: What does 85-5-5-5 mean in gunmetal bronze?

85-5-5-5 describes the nominal percentage composition by weight: 85 percent copper, 5 percent tin, 5 percent zinc, and 5 percent lead. This is the classic gunmetal formulation used since the 18th century for ordnance (gun metal) and later for valves, fittings, and marine hardware. The four components are balanced to optimise pressure tightness, corrosion resistance, castability, and machinability simultaneously.

Q2: What are the mechanical properties of 85-5-5-5 gunmetal bronze?

Typical mechanical properties per ASTM B62 (C83600): Tensile strength 240 to 280 MPa (35 to 40 ksi), Yield strength 110 to 140 MPa (16 to 20 ksi), Elongation 13 to 18 percent, Brinell hardness 65 to 85 HB. These are moderate-strength values, but the alloy compensates with outstanding casting characteristics and corrosion resistance. For applications requiring higher strength, C92200 (Navy M bronze) or C95400 (aluminium bronze) should be considered.

Q3: What is the maximum operating pressure and temperature for 85-5-5-5 gunmetal castings?

85-5-5-5 gunmetal bronze pressure vessel castings per ASTM B62 are rated for: Class 125 flanged fittings at 200 psi (14 bar) in steam and 400 psi (28 bar) in water per ASME B16.15; threaded fittings at working pressures up to 250 psi (17 bar). Maximum continuous service temperature is 290 degrees Celsius (550 degrees Fahrenheit) in steam service. Above this temperature, tin migration and alloy degradation can occur.

Q4: What is the difference between 85-5-5-5 gunmetal and phosphor bronze for castings?

85-5-5-5 gunmetal (C83600) contains lead for machinability and zinc for fluidity, making it excellent for complex valve bodies and fittings with multiple passages. Phosphor bronze (C90700, 89-10-0-1, 10% tin) contains no zinc or lead, offering higher tin content for harder bearing surfaces, better wear resistance, and higher fatigue strength. Phosphor bronze is preferred for bearing bushes, worm gears, and spring elements; gunmetal for valves, pumps, and pipe fittings.

Q5: Is 85-5-5-5 gunmetal bronze used in marine applications?

Yes. Gunmetal 85-5-5-5 has outstanding resistance to seawater, salt air, and marine atmospheric corrosion — much better than steel, aluminium, or standard brass. It has been used for marine hardware (portlights, seacocks, through-hulls, deck fittings), naval valves, and ship fittings for over 200 years. Its stability in seawater at moderate velocities (below 2 m/s) is excellent; for higher velocity seawater, aluminium bronze (C95400) is preferred.

Q6: Can gunmetal 85-5-5-5 be used for NSF 61 potable water applications?

Standard 85-5-5-5 gunmetal with 5 percent lead cannot meet NSF/ANSI 372 low-lead (0.25 percent maximum weighted average) requirements for potable water contact surfaces in the USA. For NSF 372 and California AB 1953 compliance, lead-free bronze alloys such as C89833 (bismuth-bronze), C87850, or C84850 must be specified. We manufacture castings in these low-lead and lead-free alloys for US potable water market customers.

Q7: What quality documentation is provided with gunmetal bronze castings?

Standard documentation includes: Material Test Certificate (MTC) confirming chemical composition per ASTM B62 (C83600) or BS EN 1982 (CC491K), Certificate of Conformance (CoC) to ISO 9001:2015, dimensional inspection report on sample pieces from each production batch, and heat/lot number traceability. For pressure-retaining castings, hydraulic pressure test certificates are provided. Third-party inspection by SGS, BV, or TUV is available on request.

Q8: What is the difference between sand-cast and die-cast 85-5-5-5 gunmetal bronze?

Sand casting uses expendable sand moulds, allowing complex internal passages, undercuts, and large sizes at relatively low tooling cost (USD 500 to 3000 per pattern). Dimensional accuracy is CT8 to CT10 with surface finish Ra 12 to 25 microns. Gravity die casting uses permanent metal dies (USD 3000 to 15000 per die), producing CT5 to CT7 accuracy and Ra 5 to 10 micron surface finish, suitable for high-volume production of smaller fittings. Die castings have better density and pressure tightness than sand castings for equivalent wall thickness.

Q9: What size range is available for gunmetal 85-5-5-5 sand castings?

Our sand casting capability covers individual casting weights from 50 grams to 500 kilograms. Overall envelope up to 1200 by 800 by 600 mm. For valve bodies, typical sizes are DN15 (half inch) to DN200 (8 inch) and beyond. Very large castings (above 200 kg) may require split pattern and multiple mould sections. Minimum wall thickness achievable in sand casting is approximately 4 to 5 mm for gunmetal bronze.

Q10: What is the typical lead time for gunmetal bronze sand castings?

New pattern manufacture: 2 to 4 weeks. First casting run after pattern approval: 1 to 2 weeks. Machining of castings: add 1 to 3 weeks. Total lead time for first machined and inspected castings: 5 to 8 weeks. Repeat orders on existing patterns: rough castings in 1 to 2 weeks; fully machined in 3 to 4 weeks. We hold safety stock of common casting blanks for emergency deliveries.