Yuhong Group Co., Ltd. supplies ASME SB111 C68700 aluminum brass condenser and heat exchanger tube bundles, along with companion equipment including pressure vessels, air-cooled heat exchangers, and components such as tubesheets, baffles, and heads. The C68700 arsenical aluminum brass bundle is a seamless product built under ASME SB111 / ASTM B111, with UNS C68700 and equivalent designations CZ110 (BS), CuZn20Al2 (DIN), and C6870 (JIS).
| Parameter | Value |
|---|---|
| Standard | ASME SB111 / ASTM B111 |
| UNS No. | C68700 |
| Temper | O61 (annealed) |
| Tensile Strength | ≥345 MPa |
| Yield Strength | ≥125 MPa |
| Thermal Conductivity | 109 W/(m·K) at 20°C |
| Typical OD | 15.88–25.4 mm |
| Wall Thickness | 0.5–1.2 mm |
| Max Length | Up to 6,000 mm |
| Arrangement | Straight or U-bend |
ASME SB111 C68700 corresponds to the following designations across regional standards:
| Region / Standard | Designation |
|---|---|
| UNS | C68700 |
| German DIN | CuZn20Al2 |
| Chinese GB | HAl77-2 |
These equivalents reflect the same chemistry window mandated by ASME SB111: Cu 76.0–79.0%, Al 1.8–2.5%, As 0.02–0.06%, Zn balance, with Fe and Pb each capped at 0.06% and 0.07% respectively.
The alloy’s seawater performance rests on two mechanisms. Aluminum at 1.8–2.5% forms a tenacious alumina film that resists impingement attack in high-velocity cooling water. Arsenic at 0.02–0.06% suppresses dezincification, the selective zinc loss that degrades ordinary brass tubes in chlorinated or brackish environments. Field data indicate a corrosion rate below 0.01 mm/year in seawater service, with service life exceeding 15 years under controlled flow conditions. Flow velocity should be monitored; over-chlorination beyond 3 ppm can elevate corrosion rates even in inhibited aluminum brass.
Tubes are produced by casting, extrusion, drawing, and annealing to the O61 temper specified in ASME SB111. Each tube undergoes 100% eddy current testing and hydrostatic pressure testing at 1.5 times the design pressure. Mercurous nitrate and ammonia vapor tests further screen for residual stress and stress-corrosion susceptibility. Dimensional tolerances are held at ±0.05 mm on OD and ±10% on wall thickness. Material test certificates accompany every shipment.
Coastal power plant condensers
Shipboard cooling and heat exchange systems
Offshore platform heat exchangers
Seawater desalination evaporators
Petrochemical cooler and condenser units
Industrial refrigeration and HVAC condensers
Q: Aluminum brass or admiralty brass — how do I choose?
Admiralty brass (C44300) suits fresh or lightly brackish water at moderate velocity. When cooling water velocity is high enough to cause impingement attack on admiralty tubes, C68700 is the specified upgrade because its alumina film reforms faster than flowing water can erode it.
Q: Can C68700 tube bundles be used with ammonia-bearing media?
Copper alloys, including C68700, are susceptible to stress corrosion cracking in ammonia environments. Stainless steel or non-copper materials should be specified where ammonia exposure is likely.
Q: What flow velocity is acceptable?
Design guidance generally recommends limiting flow velocity to approximately 2 m/s for sustained service, though actual limits depend on water chemistry, temperature, and solids content.
Q: Are alternative standards acceptable?
This product is manufactured and certified to ASME SB111. Equivalents in BS, DIN, and JIS are provided for reference only; the governing specification remains ASME SB111.
Contact: For technical inquiries or quotation requests, reach us at vladimir@steelseamlesspipe.com.
