What is UNS C68700 Brass Sheet?
UNS C68700 is an aluminum brass alloy containing roughly 76–79 % copper, 20–24 % zinc, 1.8–2.5 % aluminum, and 0.02–0.06 % arsenic added as a dezincification inhibitor. The arsenic addition makes C68700 the workhorse alloy for saline, brackish, and mildly polluted seawater - environments where plain brasses fail within a few service seasons.
Customer Visit & Project Reference – India
We successfully supplied ASTM B111 C68700 aluminum brass tubes to a customer in India for shell & tube condenser applications. During the project, the customer visited our facility for production inspection and quality verification. All tubes were manufactured in accordance with ASTM B111 requirements and delivered with complete Material Test Certificates (MTC), ensuring full heat number traceability and verified chemical and mechanical properties.
Download ASTM B111 C68700 MTC (PDF)
Procurement Capabilities for C68700 Copper Tube Orders
1. Make & Model - Manufacturer Identification
Each shipment of seamless Aluminum brass tubes is released under a clear manufacturer designation listing the UNS C68700 designation, the ASTM B 111 reference, and the producing mill's heat number. The make/model line links a specific heat, a specific drawing cycle, and a specific QA release - so traceability runs from the raw billet back to the dispatch note. The same heat number is stamped on the mill test certificate, on the Certificate of Conformity, on the Certificate of Origin, and on the outside of every wooden case.
2. Delivery Period & Incoterms of Delivery
Standard mill lead time for stock-allowance dimensions (16–50 mm OD, 1.0–3.0 mm wall) is 15–25 working days for production plus 7–10 days for export documentation. Custom dimensions, special tempers, or U-bend forming extend lead time to 30–45 working days. Quotations are routinely released against EXW Tianjin/Shanghai, FOB China main ports, FCA, CFR, and CIF - every Incoterm line is paired with gross/net weight, case count, and 20'/40' container loading quantity so freight can be costed before release.
3. Warranty Period
Goods are warranted against manufacturing defects and material non-conformance for 12 months from the B/L date. Warranty covers dimensional out-of-tolerance, mechanical properties outside ASTM B 111 limits, surface defects deeper than 0.1 mm, and any material-mix-up identified by independent assay. Warranty does not cover damage from improper storage, incorrect installation, or service outside the agreed design envelope.
4. Country of Origin (C/O)
Country of Origin for all quoted items is the People's Republic of China. The COO is issued on the producing mill's letterhead, signed and stamped, and is presented alongside the commercial invoice for customs clearance in the destination country. Where a free-trade agreement applies - RCEP, China-ASEAN, China-Korea, China-Pakistan, and similar - the matching FORM A / FORM E / FORM F / FORM RCEP / FORM China-Pakistan is released with the shipment at no extra charge when the purchaser flags the requirement at order stage.
5. Approximate Weight & Dimensions for INCO Freight
Each line in the quotation table lists outer diameter, wall thickness, length (mm), quantity per heat, theoretical weight per tube, total weight per line item, and total weight per order, accurate to within ±2 % of actual scale weight. For FOB China quotations, gross weight and case dimensions are given so the freight desk can book directly. For CFR / CIF quotations, the freight element is itemised to a named destination port and held for 30 days from quotation date.
6. Technical Data Sheet / Catalogue / Photos
C68700 Copper Alloy Technical Datasheet
A complete TDS is attached to every offer and covers chemical composition limits, mechanical properties for the offered temper, dimensional tolerances per ASTM B 111, hydraulic and eddy-current test pressures, and reference applications. A product catalogue covering the full C68700 inventory - outer diameter 6–108 mm, wall thickness 0.5–10 mm, lengths up to 12 m straight or U-bent - is downloadable in PDF. Pre-shipment photos (bare tubes, end caps, fumigation mark, bundle layout, case interior, case exterior with stamp) are sent at least 48 hours before container loading.
7. Factory Calibration Certificate & Material Test Certificate
Every dispatch is accompanied by an EN 10204 Type 3.1 Material Test Certificate issued by the producing mill's QA department, listing the heat number, the heat analysis (Cu / Zn / Al / As / Fe / Pb / Sn / Ni), and the tensile / yield / elongation / hardness results of the test bar, plus confirmation that the lot passed the hydraulic and eddy-current tests prescribed by ASTM B 111. Where a separate calibration certificate applies to measuring instruments or gauges used during inspection, it is added as an appendix to the MTC.
8. Certificate of Conformity (COC) from OEM
Each shipment carries an OEM-issued Certificate of Conformity confirming that the goods comply with the standards and dimensions stated in the quotation. The COC references the order number, heat number, ASTM B 111 clause, dimensions, quantity, and bears the mill's stamp and authorised QA signature. This document is mandatory for refinery and OEM release and is required alongside the MTC at goods receipt.
C68700 Specifications
The table below summarises the standard specification window released against ASTM B 111 UNS C68700 seamless aluminum brass tubes. Where a project specification is tighter than the default - for example a tighter OD tolerance on a tube-in-shell heat-exchanger bundle - the standard is overridden and the override is annotated on the MTC.
| Parameter | Value |
|---|---|
| UNS designation | UNS C68700 |
| Common name | Aluminum Brass, arsenical aluminum brass (As-inhibited) |
| Applicable standards | ASTM B 111, B 359, B 395, B 543, B 552 |
| Chemical composition (nominal) | Cu 76.0–79.0 %, Zn 20.0–24.0 %, Al 1.8–2.5 %, As 0.02–0.06 %, Fe ≤ 0.06 %, Pb ≤ 0.07 %, Sn ≤ 0.10 % |
| Condition / temper | Light-annealed (O50), Drawn (H55), Hard (H80), as specified |
| Tensile strength | ≥ 345 MPa (annealed); up to 485 MPa (drawn) |
| Yield strength (0.5 % offset) | ≥ 125 MPa (annealed); up to 345 MPa (drawn) |
| Elongation in 50 mm | ≥ 30 % (annealed); ≥ 8 % (hard) |
| Hardness | ~ 70–100 HRB (annealed); up to ~ 150 HV (drawn) |
| Outer diameter (OD) | 6.00 – 108.00 mm (typical production range 16 – 50 mm) |
| Wall thickness (T) | 0.50 – 10.00 mm |
| Length (L) | Up to 12 000 mm straight; U-bend radius per drawing |
| OD / WT tolerance | Per ASTM B 111; tighter tolerances on request (e.g. ±0.05 mm on small OD) |
| Hydraulic test | Each tube tested at mill pressure calculated per B 111 (no leakage) |
| Eddy-current test | Per ASTM E 213, calibrated on notches per E 215 |
| Available forms | Straight tube, U-bend tube, coiled tube, integral low-fin tube |
| Related products | C68700 elbow fittings, 90°/180° return bends, ASME B16.22 solder-joint fittings, tube sheets in C68700-clad plate, companion UNS C44300 / C70600 / C71500 tubes for mixed condenser bundles |
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Equivalent Grades for UNS C68700
The table below lists equivalent designations for UNS C68700 across the major international standard systems. For project teams whose internal specification is written against a national code other than ASTM, this table lets the engineering office check the same alloy under the local code without re-engineering the material call-out.
| Standard System | Standard / Designation | Equivalent Grade |
|---|---|---|
| UNS | UNS C68700 | C68700 |
| ASTM | ASTM B 111 / B 359 / B 395 / B 543 / B 552 | C68700 (aluminum brass tube) |
| EN | EN 12449 / EN 12163 / EN 12165 (CuZn20Al2As family) | CW702R / CuZn20Al2As |
| DIN | DIN 17671 / DIN EN 12449 | CuZn20AlAs (Werkstoff-Nr. 2.0460) |
| BS (UK) | BS 2871 / BS EN 12449 | CZ110 (arsenical aluminum brass family) |
| GB/T (China) | GB/T 8890 / GB/T 2040 | HAl77-2 (HAL77-2) |
| JIS (Japan) | JIS H 3300 / JIS H 3601 | C6870 / C6870T |
C68700 vs Similar Alloys
C68700 sits in a small family of corrosion-resistant tube alloys. The table below summarises the most common engineering choices that project teams and heat-exchanger designers weigh when they specify a tube alloy for condenser and heat-exchanger service.
| Property | UNS C68700 (Aluminum Brass) | UNS C44300 (Admiralty) | UNS C70600 (Cu-Ni 90/10) | UNS C71500 (Cu-Ni 70/30) |
|---|---|---|---|---|
| Nominal composition | Cu 77 / Zn 22 / Al 2 / As | Cu 71 / Zn 28 / Sn 1 / As | Cu 88 / Ni 10 / Fe 1 / Mn | Cu 69 / Ni 30 / Fe 0.5 / Mn |
| Dezincification resistance | Excellent (As-inhibited) | Good (As-inhibited) | N/A (no Zn) | N/A (no Zn) |
| Seawater biofouling tolerance | High | High | Moderate–high | High |
| Typical tensile strength | 345–485 MPa | 310–415 MPa | 260–370 MPa | 370–520 MPa |
| Thermal conductivity | ~ 100 W/m·K | ~ 110 W/m·K | ~ 50 W/m·K | ~ 30 W/m·K |
| Relative cost | Medium | Low–medium | High | Highest |
| Common service | Condenser / oil cooler / desalination | Condenser (low-pollution water) | Seawater piping, shipboard | High-pressure salt service |
| ASTM tube standard | ASTM B 111 | ASTM B 111 / B 543 | ASTM B 111 / B 466 | ASTM B 111 / B 467 |
Selection rule of thumb. When service is brackish or polluted seawater and thermal conductivity is a priority, many engineers specify UNS C68700 over C70600. When the fluid is clean seawater on a long pipeline rather than a tube-in-shell heat exchanger, many project teams move to seamless C70600 copper-nickel tubes for the better erosion-corrosion margin. For the highest-pressure or highest-temperature salt service, the C71500 family is selected instead.
Ask Our Engineers to Compare C68700 vs C70600 for Your Service
FAQ
Q: 1. What standards cover C68700 seamless aluminum brass tubes?
A: The primary standards are ASTM B 111, ASTM B 359, ASTM B 395, ASTM B 543, and ASTM B 552. ASTM B 111 is the one most commonly referenced for seamless condenser and heat-exchanger tubes. Equivalents are released under EN 12449 (CW702R), DIN 17671 (CuZn20AlAs / 2.0460), GB/T 8890 (HAl77-2), BS 2871 (CZ110), and JIS H 3300 (C6870).
Q: 2. What is the standard chemical composition of UNS C68700?
A: The nominal chemistry is Cu 76–79 %, Zn 20–24 %, Al 1.8–2.5 %, As 0.02–0.06 %; Fe, Pb, Sn and other elements are held within ASTM B 111 limits. The arsenic addition is what gives C68700 its dezincification resistance in saline water.
Q: 3. What sizes are available?
A: Standard outer diameters run from 6.00 mm to 108.00 mm with wall thicknesses of 0.50–10.00 mm, in straight lengths up to 12 m or in U-bent configurations. Custom sizes outside this envelope are released against a dedicated drawing cycle.
Q: 4. What documentation ships with each lot?
A: Each heat ships with an EN 10204 Type 3.1 Material Test Certificate, Certificate of Conformity (COC), Certificate of Origin (COO), commercial invoice, packing list, and - for destinations covered by a free-trade agreement - the matching FORM (A / E / F / RCEP). Pre-shipment photos are released 48 hours before container loading.
Q: 5. Can third-party inspectors verify the lot before shipment?
A: Yes. The mill welcomes SGS, BV, TÜV, Lloyd's, Intertek, or any other inspection body nominated by the purchaser. Witness of heat analysis, mechanical testing, dimensional checks, hydraulic test, eddy-current test, and visual surface inspection can be combined into a single inspector visit; the cost is borne by the purchaser unless otherwise agreed.
Q: 6. Is UNS C68700 suitable for potable-water or food-grade service?
A: C68700 is metallurgically acceptable for non-potable industrial water, glycol loops, and many food-processing heat-exchange circuits, but for direct potable-water service most national codes (4MS, DVGW, NSF) require a different alloy family - typically Cu-Ni or stainless. Confirm the local code before specifying C68700 for drinking-water lines.
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