Bundy Tube – Double-Wall Copper-Plated Low-Carbon Steel Tube for Automotive Use

Material Overview

Bundy tube is a double-wall low-carbon steel tube manufactured by rolling a steel strip into a 720° overlap and copper-brazing the seam. This produces a concentric double-wall tube with a continuous brazed bond between the two walls.

For automotive brake and fuel lines, this design offers:

• The mechanical strength and rigidity of steel

• The corrosion protection and brazeability of a copper layer

• Redundant double-wall pressure containment for safety

Your product, Bundy Tube Double-Wall Low Carbon Steel Tube Surface Copper Plating For Automobile, is designed specifically for automotive hydraulic and fuel systems.

Specifications

• Base metal

  • Low-carbon steel strip (e.g. AISI 1008 / 1010, EN E195, JIS STKM11A, GB Q215 equivalents)

• Construction

  • Double-wall, copper-brazed along a 720° overlap seam

• Outside diameter (OD)

  • Common automotive sizes: 4.76 mm, 6.35 mm, 8.0 mm

  • General capability range: approx. 3.17–15 mm

• Wall thickness

  • Single wall: typically 0.5–0.7 mm

  • Effective total wall (double-wall): about 2 × single-wall thickness

• Surface finishes (our selectable options)

  • Copper plating

  • Zinc plating

  • Color zinc plating (yellow chromate–treated zinc)

• Supply condition

  • Annealed / normalized after brazing

  • Straight lengths (e.g. 6 m) or level-wound coils

• Optional additional coatings

  • PVF, PA (nylon), PVC, or epoxy over metallic plating if higher corrosion resistance is required

Key Features – Our Advantages

1. High Pressure and Fatigue Safety Margin

   • Double-wall brazed construction gives high burst strength and excellent vibration fatigue resistance, ideal for brake and fuel lines.

   • Mechanical properties can be aligned with SAE J527-type requirements for yield, tensile strength, and elongation.

2. Flexible Surface Protection Options

   • We can supply tubes with copper-plated, zinc-plated, or color-zinc-plated (yellow chromate) surfaces to match different OEM corrosion requirements and cost levels.

   • Multi-layer systems (metallic plating plus organic coating) can be engineered for harsh road-salt and stone-chip environments.

3. Excellent Formability and Workability

   • Low-carbon, annealed steel provides good ductility for tight bending, double flaring, beading, and other end forming operations.

   • Suitable for complex routing along the vehicle chassis and through the engine compartment without cracking when correct tooling is used.

4. Dimensional Precision and Internal Cleanliness

   • Cold-drawn precision tube with tight tolerances on OD, wall thickness, and ovality.

   • Clean internal surface, helping to protect sensitive brake and fuel system components from contamination.

5. Reliable Joining Performance

   • Copper-bearing system supports consistent brazing quality and strong joints at fittings and brackets.

   • Compatible with common automotive connection types such as double flares, ISO flares, and appropriate compression or quick-connect fittings.

Chemical Composition

Mechanical Properties 

Applicable Standards 

We can manufacture and qualify Bundy tube in accordance with the main international frameworks, including:

• SAE / ASTM

  • SAE J527 – Brazed double-wall low-carbon steel tubing for automotive use

  • ASTM A254 – Copper-brazed double-wall steel tubing

• EN / EU

  • EN 10305-2 – Welded cold-drawn precision steel tubes (E195 and related grades)

• JIS (Japan)

  • JIS G3445 – Carbon steel tubes for machine structural purposes (STKM11A)

• GB (China)

  • GB/T 700, GB/T 3524 – Carbon structural steels and strip (including Q215 for Bundy strip and tube)

Application Fields 

General Areas

Double-wall copper- or zinc-plated Bundy tube is used in:

• Automotive hydraulic and fuel systems

• Refrigeration and air-conditioning units

• General fluid and gas control lines in machinery and appliances

Typical Automotive Uses

• Hydraulic brake lines (chassis lines, cross-axle lines)

• Fuel feed and return lines (gasoline and diesel)

• Transmission oil cooler and power steering lines (where applicable)

• Auxiliary oil and coolant circuits where steel tubes are specified

Q: Are you trading company or manufacturer ?

A: manufacturer,also can do trading.

Q: How long is your delivery time?

A: Generally speaking,it is 10-15 days if the goods are in stock,or it is 30-40 days if the goods are not in stock,

it is according to quantity.

Q: Do you provide samples? is it free or extra ?

A: Yes, we could offer the sample for free charge but need pay the cost of freight.

Q: What is your terms of payment ?

A: Payment<=2000USD, 100% in advance. Payment>=2000USD, 30% T/T in advance ,balance before shippment.

If you have another question, pls feel free to contact with me.