ASTM B111 C68700 aluminum brass tube costs 40-50% less than C70600 copper nickel, but lasts 15-20 years instead of 20-25 years in seawater. For most buyers, C68700 delivers better value. For ammonia service or temperatures above 80°C, C70600 is required. This guide walks through real project scenarios, cost models, and a decision tree. GNEE (China) supplies both alloys.
Which Alloy for Which Job?
| Project Condition | Recommended Alloy | Why |
|---|---|---|
| Clean seawater, <50°C, continuous flow | C68700 | 40-50% cheaper, 15-20 year life |
| Polluted seawater (sulfide, low pH) | C68700 nano-treated | 8x better than brass, matches CuNi |
| Warm seawater 50-80°C | C68700 nano-treated | Standard C68700 degrades above 60°C |
| Seawater >80°C | C70600 | C68700 oxide film breaks down |
| Ammonia in water (fertilizer, chemical) | C70600 | C68700 cracks in weeks |
| High velocity >5.2 m/s | Neither – use titanium | Both alloys erode above limit |
| Budget-constrained project | C68700 | Lowest upfront and annualized cost |
| 25-year design life with no replacement | C70600 | C68700 may need replacement at year 18-22 |
GNEE bottom line: For 80% of seawater applications, C68700 is the smarter purchase. Only pay for C70600 when specific conditions require it.
New Build Seawater Cooling System – 15-Year Operation
Project: New chemical plant in Singapore. Seawater cooling. Flow continuous. Temperature 28-32°C. Design life 15 years. Total tube length 5,000 meters. Size 25mm OD x 2.0mm wall.
Cost comparison (GNEE quotes, FOB China):
| Cost Item | C68700-O60 | C70600-O60 | Difference |
|---|---|---|---|
| Price per kg | $12 | $21 | C68700 saves $9/kg |
| Price per meter | $15 | $26 | C68700 saves $11/m |
| Total material cost | $75,000 | $130,000 | C68700 saves $55,000 |
| Expected life | 15-20 years | 20-25 years | Both exceed 15-year design |
| Replacement needed within design life? | No | No | Tie |
| Annualized cost (15 years) | $5,000/year | $8,700/year | C68700 saves $3,700/year |
Decision: C68700 wins. The project only needs 15 years. Paying 73% more for C70600 buys life that is not needed.
GNEE comment: This is the most common scenario. Buyers who automatically specify C70600 waste $50,000-100,000 per project.
Polluted Harbor – Power Plant Intake
Project: Power plant in Rotterdam harbor. Seawater has sulfide (0.5-1.0 ppm) from shipping. Temperature 15-25°C. Design life 20 years. Tube size 25mm x 2.5mm.
Cost comparison (with nano-treated C68700):
| Cost Item | C68700 Nano-Treated | C70600 Standard | Difference |
|---|---|---|---|
| Price per kg | $15 | $21 | C68700 saves $6/kg |
| Expected life in polluted water | 15-18 years | 20-22 years | C70600 lasts 3-5 years longer |
| Replacement needed at year 20? | Maybe (15-20% chance) | No | C70600 advantage |
| 20-year annualized cost | $6,500-7,200/year | $7,800-8,500/year | C68700 still lower |
Decision: C68700 nano-treated still wins on cost. However, if downtime for replacement is extremely expensive (e.g., nuclear plant), pay for C70600.
GNEE data: In GNEE's Rotterdam harbor test (3 years), nano-treated C68700 dezincification was 0.032 mm/year. C70600 had no dezincification (no zinc to leach). But C68700 cost 30% less.
High Temperature – Desalination Brine Heater
Project: Desalination plant. Brine temperature 75-85°C. Seawater. Design life 20 years. Tube size 32mm x 2.5mm.
Cost comparison:
| Cost Item | C68700 High-Al (2.4%) | C70600 | Difference |
|---|---|---|---|
| Price per kg | $16 | $22 | C68700 saves $6/kg |
| Expected life at 80°C | 8-12 years | 20+ years | C70600 wins |
| Replacements in 20 years | 1 or 2 | 0 | C70600 advantage |
| 20-year total cost (incl replacements) | $120,000-150,000 | $110,000-130,000 | C70600 slightly lower |
Decision: C70600 wins. Above 70°C, C68700 life drops significantly. For high-temperature seawater, pay for C70600.
GNEE note: Some buyers use C68700 up to 70°C successfully. Above 70°C, GNEE recommends C70600 or titanium.
Ammonia Service – Fertilizer Plant Cooling
Project: Fertilizer plant. Cooling water contains 2-5 ppm ammonia. Temperature 40°C. Tube size 19mm x 2.0mm.
Cost comparison – but C68700 is not an option:
| Parameter | C68700 | C70600 |
|---|---|---|
| Ammonia resistance | Poor – fails in weeks | Good |
| Expected life | 1-6 months | 15-20 years |
| Is it usable? | No | Yes |
Decision: C70600 is the only choice. Do not use C68700 in any ammonia-containing water. Test your water for NH₃ before ordering.
GNEE warning: GNEE has seen C68700 tubes fail in 3 weeks in ammonia service. The cost savings do not matter if the product does not work.
Total Cost of Ownership – 5, 10, 15, 20 Year Models
Assumptions: 1,000 meters of 25mm x 2.0mm tube. Seawater, clean, 30°C. No ammonia.
| Time Period | C68700 Cost | C70600 Cost | Savings with C68700 |
|---|---|---|---|
| Year 0 (purchase) | $15,000 | $26,000 | $11,000 |
| Year 5 (maintenance) | $1,000 | $800 | $200 |
| Year 10 (maintenance) | $1,500 | $1,200 | $300 |
| Year 15 (inspection) | $2,000 | $1,500 | $500 |
| Year 20 (if replacement needed) | $15,000 (C68700) | $0 (C70600 still good) | -$15,000 |
| Total by year 15 | $19,500 | $29,500 | C68700 saves $10,000 |
| Total by year 20 | $34,500 (if replaced) | $29,500 | C70600 saves $5,000 |
Break-even point: Year 18-19. If your project life is less than 18 years, C68700 saves money. If more than 18 years, C70600 eventually wins.
GNEE tip: Most industrial projects have a 15-20 year design life. For these, C68700 is the lower-cost choice.
Supply Chain Comparison – Availability and Lead Time
| Supply Factor | C68700 (GNEE) | C70600 (GNEE) |
|---|---|---|
| Stock availability (common sizes) | High – 50+ tons | Limited – 10-15 tons |
| Lead time – stock sizes | 7-10 days | 15-20 days |
| Lead time – custom sizes | 20-25 days | 30-40 days |
| MOQ – stock sizes | 500 kg | 1,000 kg |
| MOQ – nano-treated | 200 kg | Not available |
| Minimum cut length | 1 meter (repair pieces) | 3 meters |
| Number of suppliers globally | Many (China, India, Europe) | Fewer (specialty mills) |
GNEE comment: C68700 is much easier to source. If you need tubes quickly or in small quantities, C68700 is the practical choice. C70600 often requires longer lead times and larger MOQs.
What to Specify for Each Alloy
When buying C68700 from GNEE:
ASTM B111 / ASME SB111
C68700 (aluminum brass) – verify Al 1.5-2.5%
Temper: O60 (annealed) for expansion / H80 for straight pipe
Wall thickness: 2.0 mm minimum for seawater
Nano-treated? Yes/No (adds 18-22% cost, +40% life)
ASTM G48 dezincification test report (included)
EN 10204 3.1 mill certificate
When buying C70600 from GNEE:
ASTM B111 / ASME SB111
C70600 (copper nickel 90/10) – verify Ni 9-11%
Temper: O60 (annealed) only
Wall thickness: 1.5 mm minimum (stronger than C68700? No – actually weaker in tensile)
No nano-treatment available for C70600
Corrosion test per ASTM G52 (not G48 – different standard)
EN 10204 3.1 mill certificate
FAQ
Q1: Which is cheaper – ASTM B111 C68700 or C70600?
A: C68700 is 40-50% cheaper for the same dimensions.
Example: 25mm x 2.0mm tube. C68700 = $11-14/kg. C70600 = $18-24/kg. For a 5,000-meter project, C68700 saves $40,000-60,000. Only pay for C70600 if your conditions require it.
Q2: Does C70600 last longer than C68700 in seawater?
A: Yes – 20-25 years vs 15-20 years for C68700 in clean seawater.
C70600 has no zinc, so no dezincification. However, the 5-year difference matters only for projects with >20-year design life. For 15-year projects, both exceed requirements – so buy the cheaper one (C68700).
Q3: Can C68700 replace C70600 in existing systems?
A: Yes – if the system has no ammonia and temperature <70°C.
GNEE has helped 30+ plants replace C70600 with C68700. Use the same dimensions. Nano-treated C68700 matches C70600 corrosion resistance in most conditions. Savings: 30-50% on replacement tube cost.
Q4: What is the tensile strength difference between C68700 and C70600?
A: C68700 is stronger – 550-750 MPa vs 350-520 MPa for C70600.
Many buyers assume C70600 is stronger because it costs more. Not true. For high-pressure systems, C68700 is the better choice mechanically.
Q5: Does GNEE stock both C68700 and C70600?
A: Yes – GNEE stocks both alloys at our China warehouse.
C68700 stock: 50+ tons (12-50mm OD, 2-5mm wall). C70600 stock: 10-15 tons (limited sizes). For C70600, confirm stock before ordering. Lead time for non-stock C70600: 30-40 days.
Q6: How do I decide which alloy to buy for my project?
A: Use the GNEE decision tree in Section 6.
Answer three questions: (1) Is there ammonia? (2) Is temperature above 80°C? (3) Is design life over 20 years? If yes to any – consider C70600. If no to all – buy C68700.
Q7: What is the price difference for nano-treated C68700 vs C70600?
A: Nano-treated C68700 ($14-18/kg) is still 15-25% cheaper than C70600 ($18-24/kg).
Nano-treated C68700 adds 40% corrosion life, closing the gap with C70600. For polluted seawater, GNEE recommends nano-treated C68700 over standard C70600 – similar performance at lower cost.
100% Inspection Per ASTM B111 / C68700 – Customer Witnessed
Every lot of C68700 material undergoes a multi-step inspection protocol:
1) Chemical composition verified by Oxford Spectrometer (meeting ASTM B111/B135).
2) Mechanical properties tested via 300kN universal tester for tensile strength (≥370MPa) and hardness (80-110 HRB).
3) Dimensional accuracy checked by laser micrometer and pneumatic gauge.
4) Anti-corrosion validation includes mercurous nitrate test and dezincification depth analysis (≤200μm per ASTM B858).
5) Non-destructive testing – 100% eddy current or ultrasonic flaw detection.
We provide traceable mill test certificates (MTC) for each shipment, with third-party inspection (SGS/BV) available upon request.
Export-Ready Packing – Anti-Rust & Wooden Case
After passing inspection, all tubes are packed according to export standards and customer-specific requirements. The packing process is documented below to ensure traceability and damage-free delivery.
Packing steps shown in video & images:
1. Tube cleaning & drying
2. Plastic end caps on both ends
3. VCI anti-rust paper wrapping
4. Bundle strapping with moisture barrier film
5. Plywood wooden case (ISPM-15 compliant) with foam padding
6. Labeling with ASTM grade, lot number, and inspection stamp
Our Factory & Equipment
Our C68700 (Aluminum Brass) production line is equipped with Germany-derived continuous extrusion presses, high-precision tandem cold rolling mills, and online solution heat treatment furnaces. The automated casting system ensures homogeneous distribution of aluminum and arsenic elements, while the in-line eddy current testing devices monitor surface defects in real time. With CNC-controlled straightening and cutting machines, we can supply C68700 tubes and rods in custom lengths (±0.5mm tolerance), supporting OD from 6mm to 219mm for condenser and heat exchanger applications.
Copper & Copper Alloy Products – Supply Range
| Product Form | Common Alloys / Grades | Size Range | Standards | Typical Applications |
|---|---|---|---|---|
| Tube / Pipe | C12200, C11000, C68700, C70600, C71500, C44300, C27000 | OD: 4mm – 219mm Wall: 0.5mm – 20mm Length: up to 15m |
ASTM B68, B75, B111, B280, B359, B466 | Heat exchangers, condensers, HVAC, plumbing, oil coolers |
| Plate / Sheet | C11000, C12200, C26000, C26800, C52100, C68700 | Thk: 0.5mm – 50mm Width: up to 1200mm Length: up to 4000mm |
ASTM B152, B169, B103, B465 | Electrical parts, roofing, gaskets, industrial panels |
| Rod / Bar | C11000, C26000, C36000, C46400, C48500, C63000 | Dia: 3mm – 120mm Length: 1m – 6m (or custom) |
ASTM B16, B124, B138, B150, B453 | Valve stems, shafts, fasteners, machined components |
| Wire | C11000, C16200, C17500, C26000, C52100, C64700 | Dia: 0.1mm – 12mm Coil weight: up to 100kg |
ASTM B1, B2, B3, B197, B206, B624 | Welding electrodes, electrical conductors, springs, mesh |
| Strip / Foil | C11000, C19400, C26000, C26800, C52100, C70250 | Thk: 0.05mm – 3.0mm Width: 5mm – 600mm |
ASTM B36, B465, B694, B888 | Connectors, terminals, battery tabs, shielding, stamping parts |
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