ASME SB111 C68700 Seamless Brass Tubes for Desalination of Seawater
C68700 is an aluminum brass alloy with arsenic addition,
specifically designed for harsh environments such as seawater
desalination. Its composition (Cu: 76-79%, Al: 1.8-2.5%, As:
0.02-0.06%, Zn: balance) ensures exceptional corrosion resistance
in seawater and high thermal conductivity. The arsenic content
further enhances resistance to dezincification, a critical feature
for long-term durability in marine applications.
The production process of Brass Tube
Raw Materials
Melting&Casting
Extrusion
Rolling
Intermediate Heat Treatment 1
Straightening
Three-line Drawing
Acid Washing
Intermediate Heat Treatment 2
Two Cascade Drawing
Cutting&Cleaning
Eddy Current Test
Final Heat Treatment
Packing
Shipping
Comparison Table of Brass Tube Alloy
Implementation Standard | Alloy Specifications |
GB/T 5231 | HAI 77-2 |
HSn70-1, HSn72-1 |
ASTM B111 | C68700 |
C44300 |
BS EN12451 | CuZn20Al2As |
CuZn28Sn1As |
JIS H3300 | C6870, C6871, C6872 |
C44300 |
AS 1569 | C68700 |
C44300 |
Chemical Composition of Brass Tube Alloys
Implementation Standard | Alloy | Cu (%) | Al/Sn (%) | As (%) | Fe (%) | Pb (%) | Other Impurities (%) | Zn (%) | Total Impurities (%) |
GB/T 5231 | HAl77-2 | 76.0-79.0 | 1.8-2.5 (Al) | 0.02-0.06 | ≤0.06 | ≤0.07 | ≤0.07 (Other) | Balance | ≤0.6 |
ASTM B111 | C68700 | 76.0-79.0 | 1.8-2.5 (Al) | 0.02-0.06 | ≤0.06 | ≤0.07 | ≤0.07 (Other) | Balance | ≥99.5 (Sum) |
ASME SB111 |
JIS H3300 | C6870 | 76.0-79.0 | 1.8-2.5 (Al) | 0.02-0.06 | ≤0.05 | ≤0.05 | ≤0.05 (Other) | Balance | - |
JIS H3300 | C6871 | 76.0-79.0 | 1.8-2.5 (Al) | 0.02-0.06 | ≤0.05 | ≤0.05 | ≤0.05 (Other); Si: 0.20-0.50 | Balance | - |
JIS H3300 | C6872 | 76.0-79.0 | 1.8-2.5 (Al) | 0.02-0.06 | ≤0.05 | ≤0.05 | ≤0.05 (Other); Ni: 0.20-1.0 | Balance | - |
BS EN12451 | CuZn20Al2As (CW702R) | 76.0-79.0 | 1.8-2.3 (Al) | 0.02-0.06 | ≤0.07 | ≤0.05 | Ni ≤0.1; P ≤0.01; Mn ≤0.1; ≤0.3 (Other total) | Balance | - |
AS 1569 | C68700 | 76.0-79.0 | 1.8-2.5 (Al) | 0.02-0.06 | ≤0.06 | ≤0.07 | ≤0.07 (Other) | Balance | - |
GB/T 5231 | HSn70-1 | 69.0-71.0 | 0.8-1.3 (Sn) | 0.03-0.06 | ≤0.10 | ≤0.05 | ≤0.05 (Other) | Balance | ≤0.3 |
GB/T 5231 | HSn72-1 | 70.0-73.0 | 0.9-1.2 (Sn) | 0.02-0.06 | ≤0.06 | ≤0.07 | ≤0.07 (Other) | Balance | ≤0.4 |
ASTM B111 | C44300 | 70.0-73.0 | 0.9-1.2 (Sn) | 0.02-0.06 | ≤0.06 | ≤0.07 | ≤0.07 (Other) | Balance | ≥99.6 (Sum) |
ASME SB111 |
JIS H3300 | C4430 | 70.0-73.0 | 0.9-1.2 (Sn) | 0.02-0.06 | ≤0.05 | ≤0.05 | ≤0.05 (Other) | Balance | - |
BS EN12451 | CuZn28Sn1As (CW706R) | 70.0-72.5 | 0.9-1.3 (Sn) | 0.02-0.06 | ≤0.07 | ≤0.05 | Ni ≤0.1; P ≤0.01; Mn ≤0.1; ≤0.3 (Other total) | Balance | - |
AS 1569 | C44300 | 70.0-73.0 | 0.8-1.2 (Sn) | 0.02-0.06 | ≤0.06 | ≤0.07 | ≤0.07 (Other) | | |
Primary Applications in Seawater Desalination
Heat Exchangers and Condensers
- C68700 tubes are widely used in multi-stage flash (MSF) and
reverse osmosis (RO) systems. Their high thermal conductivity
(64 BTU·in/(hr·ft²·°F)) ensures efficient heat transfer between
seawater and desalination equipment
- The seamless structure eliminates weld seams, reducing leakage
risks in high-pressure environments
Corrosion Resistance
- The aluminum content forms a protective oxide layer, while arsenic
prevents dezincification. This combination allows the tubes to
withstand saltwater, chlorine, and sulfide exposure, even at high
flow velocities
- Example: In seawater intake pipelines, C68700 resists pitting
and crevice corrosion, extending equipment lifespan
Mechanical Performance
- Tensile Strength: 345–600 MPa (minimum 345 MPa for annealed
tubes)
- Yield Strength: 125–540 MPa, suitable for high-pressure
condensers and evaporators.
- Fatigue Resistance: Maintains structural integrity under cyclic
thermal and mechanical stresses.
