ASTM B111 C68700 Aluminum Brass Tube

Henan Gnee New Material Co., Ltd. is one of the most professional manufacturers and suppliers of astm b111 c68700 aluminum brass tube in China, specialized in providing high quality copper products with competitive price. Welcome to buy discount astm b111 c68700 aluminum brass tube for sale here from our factory. Customized orders are welcome.

 

ASTM B111 C68700 is an aluminum brass alloy widely used in seawater-cooled heat exchangers. The addition of aluminum (1.8-2.5%) forms a protective oxide film on the tube surface, which gives this alloy better resistance to impingement corrosion compared to admiralty brass (C44300). The arsenic content prevents dezincification.

 

C68700 is specified for shell and tube heat exchanger, heat exchanger condenser, and shell tube evaporator units where cooling water is seawater, brackish water, or polluted river water. It is not typically used for fresh water or HVAC refrigerant applications – C12200 copper is the better choice for those.

 

We supply C68700 tubing to ASTM B111, ASME SB111, EN 12451, and JIS H3300 standards. Straight lengths and u tube heat exchanger bends are available.

 

Supply Form	Size Range	Length	Heat Treatment	Typical Applications
Straight Length Tubes	OD 12.7–76.2 mm	Up to 25 m	Annealed (O60) or Light Drawn (H55)	Surface condensers, shell-and-tube heat exchangers, seawater coolers
	WT 0.7–3.5 mm
U-Bend Tubes	OD 15.88–38.1 mm	Up to 20 m developed length	Annealed with optional stress-relief heat treatment after bending	TEMA heat exchangers, power plant condensers, refinery units
	WT 0.7–2.5 mm
Tube Bundle Components	Customized according to drawings	Customized	Annealed tubes with optional stress-relief treatment	Tube bundles, condensers, evaporators and heat exchanger assemblies

Available in Annealed (O60), Light Drawn (H55), and Stress-Relieved conditions in accordance with ASTM B111 and customer specifications.

 

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)

 

Element	Percentage (%)
Copper (Cu)	76.0 – 79.0
Aluminum (Al)	1.8 – 2.5
Arsenic (As)	0.02 – 0.10
Lead (Pb)	0.09 max
Iron (Fe)	0.06 max
Zinc (Zn)	remainder

 

The aluminum content is the key difference between C68700 and C44300. Aluminum forms a dense, adherent oxide layer that repairs itself when damaged. This self-repairing property is why C68700 outperforms admiralty brass in turbulent or polluted seawater.

 

The arsenic addition serves the same purpose as in C44300 – preventing dezincification. Without arsenic, the zinc in the alloy would leach out over time, leaving behind porous copper with no mechanical strength.

 

C68700 is covered under the following standards:

ASTM B111 – Standard specification for copper and copper alloy seamless condenser tubes

ASME SB111 – Same as ASTM but with additional ASME code requirements

EN 12451 – European standard (alloy designation CuZn20Al2As)

JIS H3300 – Japanese standard (alloy designation C6870T)

For ASME code applications, specify SB111 C68700 rather than ASTM B111. The chemistry is identical, but SB111 includes stricter certification and traceability.

 

Property	Value (annealed temper)
Tensile strength (min)	310 MPa (45 ksi)
Yield strength (0.5% extension, min)	105 MPa (15 ksi)
Elongation (min)	30%
Hardness (Rockwell B)	55 – 80
Thermal conductivity (20°C)	100 W/m·K
Coefficient of thermal expansion (20-300°C)	18.0 µm/m·K
Density	8.33 g/cm³
Electrical conductivity (% IACS)	23%

 

Thermal conductivity of C68700 is approximately one-quarter that of pure copper (C12200). This means a heat exchanger using C68700 tubes will require more surface area than one using copper tubes for the same duty. However, in seawater service, C12200 is not an option – it corrodes too quickly. The comparison is therefore between C68700, C44300, and cupronickel alloys, all of which have similar thermal conductivity.

 

Item	Range
OD	12.7–76.2 mm
Wall Thickness	0.7–3.5 mm
Length	Up to 25 m
Form	Straight / U Bend
Temper	Annealed / Light Drawn
Standards	ASTM B111, ASME SB111
Test	Eddy Current, Hydrostatic
Certificate	EN10204 3.1

We supply copper alloy tube for heat exchanger in the following dimensions. Stock sizes are available for immediate shipment. Non-stock sizes are produced on a 4-6 week lead time.

 

Outer diameters – stocked and commonly ordered:

copper heat exchanger tube 5/8 inch (15.88mm)

copper heat exchanger tube 3/4 inch (19.05mm)

copper heat exchanger tube 1 inch (25.4mm)

copper heat exchanger tube OD 19mm

copper heat exchanger tube OD 25.4mm

Other diameters from 12mm to 32mm are available on request.

 

Wall thickness:

Standard wall thicknesses range from 0.7mm to 2.5mm, depending on outer diameter and application requirements. BWG (Birmingham Wire Gauge) sizes such as 18 BWG (1.24mm), 16 BWG (1.65mm), and 14 BWG (2.11mm) are commonly stocked.

 

Length:

Straight tubes are available in lengths up to 30 meters. Copper heat exchanger tube length can be cut to your exact requirement. Standard cut lengths are 6m, 9m, 12m, and 18m.

 

U-bends:

We fabricate u tube heat exchanger and u tube bundle heat exchanger bends from C68700. Minimum bending radius is 3.0 × OD for annealed tube. Tighter radii are possible but require special tooling and are subject to additional quality inspection.

 

Design parameters for heat exchanger manufacturers:

Heat exchanger tube pitch – Standard is 1.25 × OD. Closer pitch is possible but requires careful cleaning considerations.

Heat exchanger tube sheet drilling – Tube holes should be drilled to a tolerance of ±0.08mm from nominal OD. Surface finish of tube holes should be 3.2 µm Ra or better for proper tube rolling.

Heat exchanger pipe diameter – For shell-side flow calculations, use the actual measured OD of the tube, not the nominal value.

Request pricing for C68700 tube

Selecting the right heat exchanger tube material requires balancing corrosion resistance, thermal performance, and cost. The table below compares C68700 with the most common alternatives.

Alloy	Best application	Thermal conductivity (W/m·K)	Relative cost	Seawater resistance
C12200 (copper)	Fresh water, HVAC	400	Low	Poor
C44300 (admiralty brass)	Clean seawater	100	Low-Medium	Good
C68700 (aluminum brass)	Polluted or variable seawater	100	Medium	Better than C44300
C70600 (90/10 cupronickel)	Aggressive seawater, long life	45	High	Excellent
C71500 (70/30 cupronickel)	Very aggressive seawater	30	Very high	Best
316 stainless steel	Chloride environments	15	Medium-High	Good but crevice risk

C68700 vs C44300: Both have similar thermal conductivity and cost. C68700 has better resistance to impingement corrosion and performs better in polluted or variable-quality water. C44300 is slightly easier to bend and roll. Choose C68700 for aggressive conditions, C44300 for clean seawater.

 

C68700 vs C70600: Cupronickel lasts longer in high-velocity seawater (above 2.5 m/s) or very aggressive conditions. However, C70600 costs 40-60% more than C68700 and has lower thermal conductivity. For most seawater applications with 20-year design life, C68700 is the more economical choice.

 

C68700 vs stainless steel: Stainless steel (316L) has better resistance to chlorides but suffers from crevice corrosion under deposits or gaskets. Stainless also has much lower thermal conductivity (15 vs 100 W/m·K). For shell and tube heat exchangers, copper alloys remain the standard for seawater service.

 

 

How to bend copper heat exchanger tube – C68700

Use annealed temper (O60) for all bending operations. Hard-drawn tube will crack.

Minimum bending radius: 3.0 × OD (compared to 2.5 × OD for C12200)

Mandrel bending is required for radii less than 5 × OD

Expect springback – over-bend by approximately 2-3 degrees for a 90-degree bend

For u tube heat exchanger bundles, inspect the outer radius of each bend for cracks after bending

 

How to weld copper heat exchanger tube – C68700

Welding is possible but not common for heat exchanger tubing. Most tube-to-tubesheet joints are made by mechanical expansion or rolling.

If welding is required:

Process: TIG (GTAW)

Filler metal: ERCuAl-A2 (aluminum bronze)

Shield gas: argon

Ventilation: required. Zinc oxide fumes are generated and are hazardous.

Pre-cleaning: remove all oil and grease from tube end and tube sheet hole

For most applications, mechanical joints are preferred over welding because they avoid the heat-affected zone and the risk of stress corrosion cracking.

 

Heat exchanger tube rolling – C68700

Proper heat exchanger tube rolling is critical for a leak-free joint. C68700 work-hardens faster than C12200, so rolling parameters differ.

Use a torque-controlled roller expander – do not rely on operator feel alone

Target wall reduction: 10-15% of original wall thickness

Rolling speed: slower than for copper to avoid work hardening the tube end

Always perform a test roll on a sample tube in a scrap tube sheet before rolling the actual bundle

After rolling, check for cracking at the tube end using dye penetrant or visual inspection with magnification

 

Heat exchanger tube expansion

For heat exchanger tube expansion (hydraulic or mechanical expansion of the tube into the tube sheet), C68700 requires higher pressure than C12200. Expansion pressure typically ranges from 150-200 bar for 19mm OD tubes with 1.24mm wall, but this varies with tube sheet material and hole geometry. Consult your expander manufacturer for specific parameters.

 

What is ASTM B111 C68700 aluminum brass tube?

It is a copper-zinc-aluminum-arsenic alloy tube manufactured to ASTM B111 for heat exchanger applications. The aluminum forms a protective oxide film that resists seawater corrosion. The arsenic prevents dezincification.

 

When should I choose C68700 over C44300?

Choose C68700 when your cooling water is polluted, has variable pH, contains silt, or when water velocity exceeds 2.0 m/s. For clean seawater at moderate velocity (below 2.0 m/s), C44300 is sufficient and easier to fabricate.

 

Can C68700 be used in fresh water?

Yes, but it is not economical. C12200 copper has four times higher thermal conductivity and lower material cost. Use C12200 for fresh water and closed-loop HVAC systems.

 

How to bend copper heat exchanger tube in C68700?

Use annealed temper tube. Minimum bend radius is 3.0 × OD. Use a mandrel bender for radii under 5 × OD. Expect springback – over-bend slightly.

 

How to weld copper heat exchanger tube in C68700?

TIG weld with ERCuAl-A2 (aluminum bronze) filler. Use argon shield gas. Provide good ventilation – zinc oxide fumes are hazardous. For most heat exchangers, mechanical tube expansion is preferred over welding.

 

What is the difference between ASTM B111 and ASME SB111?

ASME SB111 is the ASME code version of ASTM B111. Chemistry and dimensions are identical. SB111 requires additional quality assurance, certification, and traceability for pressure vessel applications. If your shell and tube heat exchanger is ASME stamped, you must order SB111.

 

Copper heat exchanger tube vs stainless steel – which is better for seawater?

Neither pure copper nor standard stainless steel is ideal for seawater. Copper alloys (C68700, C44300, C70600) are the industry standard for seawater-cooled heat exchangers. Stainless steel can suffer crevice corrosion in seawater.

 

Copper heat exchanger tube vs cupronickel – which lasts longer?

Cupronickel (C70600, C71500) lasts longer in aggressive seawater, especially at velocities above 2.5 m/s. However, cupronickel costs significantly more and has lower thermal conductivity. C68700 is the more economical choice for most seawater applications with 20-year design life.

 

Why use copper in heat exchanger applications involving seawater?

Because copper alloys offer the best combination of corrosion resistance, thermal conductivity, fabricability, and cost for seawater-cooled heat exchangers. No other material family matches this balance.

 

What is the life expectancy of C68700 heat exchanger tube?

20-30 years in properly designed and maintained seawater systems. Factors that reduce life: velocity above 2.5 m/s, sand erosion, ammonia in water, low pH, or galvanic coupling with stainless steel.

 

What causes corrosion in C68700 tubes?

Most common causes: ammonia (stress corrosion cracking), low pH below 6.0 (film dissolution), high velocity above 2.5 m/s with entrained air or sand (erosion-corrosion), or galvanic coupling with a more noble metal.

 

How to clean copper heat exchanger tube made of C68700?

Mechanical cleaning with nylon or brass brushes. Chemical cleaning with inhibited sulfamic or citric acid. Do not use hydrochloric acid or ammonia-based cleaners. For biofouling, chlorination is acceptable at free chlorine below 0.5 ppm.

 

Do you supply C68700 to EN 12451 or JIS H3300?

Yes. While ASTM B111 and ASME SB111 are our primary standards, we can certify to EN 12451 (alloy CuZn20Al2As) or JIS H3300 (alloy C6870T) on request. Specify your required standard when ordering.

 

Do you have copper heat exchanger tube for sale in small quantities?

Yes. We support repair and replacement bundles. Minimum quantity depends on stock – typically 100 meters for stock sizes. Contact us with your requirements.

 

What is the maximum length you supply?

Straight tubes up to 30 meters. Longer lengths are possible with welded joints, but welded tubes are not recommended for heat exchanger service unless specifically approved by the design engineer.

 

Do you provide third-party inspection?

Yes. We can arrange inspection by ABS, DNV, BV, Lloyds, or any other third-party agency at customer expense. Inspection must be specified at time of order.

 

Quality Control	Description	Standard
Chemical Analysis	Verify alloy composition	ASTM B111
Mechanical Testing	Tensile strength and elongation	ASTM B111
100% Eddy Current Testing	Non-destructive defect detection	ASTM E243
Hydrostatic Testing	Pressure integrity verification	ASTM B111
Dimensional Inspection	Tight tolerance control	ASTM B111
EN10204 3.1 Certificate	Full traceability and documentation	EN10204

Poor packaging destroys even the best copper heat exchanger tube. As a professional copper heat exchanger tube factory serving copper heat exchanger tube USA, Europe, UAE, Saudi Arabia, and India, we follow military-grade export packaging standards to ensure zero damage during sea or air freight.

Our Standard Packaging Process:

Packaging Stage	Material / Method	Purpose
Individual Tube Protection	Anti-rust VCI paper + plastic end caps	Prevents moisture, dust, and scratches on copper tube heat exchanger inner surfaces.
Bundling	Nylon straps + wooden spacers	Keeps copper heat exchanger tube OD 19mm, 1 inch, or 5/8 inch sizes organized and vibration-free.
Moisture Barrier	Thick PE film wrap (heat-shrunk)	Blocks humidity during long sea voyages to copper heat exchanger tube Germany or Saudi Arabia.
Outer Packing	Export-grade plywood cases or steel-banded wooden crates	Withstands stacking and rough handling. Each crate labeled with PO number, alloy (e.g., SB111 C70600), and quantity.
Documentation	Packing list + Mill Test Certificate (MTC) attached outside	Customs clearance support for copper heat exchanger tube stockist and distributor partners.

For U-Bundle Orders: U tube heat exchanger and U tube bundle heat exchanger are placed in dedicated steel jigs inside the crate to prevent bending radius distortion.

 

Equipment Type	Specification / Capability	Quality Impact
Horizontal Continuous Casting Line	10-ton capacity	Produces homogeneous copper alloy tube for heat exchanger billets with zero porosity.
Three-Roll Piercing Mill	Up to 60mm OD	Precision wall thickness control for heat exchanger tube wall thickness as low as 0.5mm.
Cold Drawing Bench	5 draws in sequence	Achieves tight tolerances on copper heat exchanger tube length and heat exchanger pipe diameter.
Straightening & Cutting Line	CNC servo-controlled	Burr-free cutting for copper heat exchanger tube 3/4 inch and 1 inch to exact project lengths.
U-Bending Machine	CNC mandrel type	Produces u tube condenser and U tube bundle heat exchanger without kinking or ovality.
Eddy Current Tester	NDT (Non-Destructive Testing)	100% inspection of C70600 tube and C71500 tube for pinholes or cracks per ASTM B111 pdf standards.
Hydrostatic Tester	Up to 200 bar	Validates heat exchanger tube expansion and tube rolling integrity.
Spectrometer	Optical emission (OES)	Confirms chemical composition of ASME SB111, EN 12451, and JIS H3300 grades on every batch.

 

Our Certifications & Compliance:

ASTM B111 pdf and ASME SB111 pdf full traceability.

ISO 9001:2015 quality management system.

Third-party inspection accepted: SGS, BV, Lloyds, or TUV.

Copper heat exchanger tube life expectancy testing reports available upon request.

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