Scope
This standard applies to brake pipes with and without flares for installation in hydraulic braking systems.
It specifies the dimensions, materials, strength and design of pipes and their flares intended for hydraulic braking systems.
1 Subject and field of application
This standard specifies the design, dimensions, materials and mechanical requirements for steel brake pipes and pipe end flares used in hydraulic braking systems of motor vehicles. The standard covers both plain-ended brake pipes and brake pipes formed with single flares.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. At the time of publication, the editions indicated were valid. DIN 17664 Copper-nickel alloy seamless tubes DIN 74233-1 Brake pipe fittings; banjo bolts DIN 74233-2 Brake pipe fittings; union nuts ISO 4038 Road vehicles — Hydraulic braking systems — Single-flare tubing
3 Terms and definitions
3.1 Brake pipe Seamless metal pipe used to transmit hydraulic brake fluid between braking components. 3.2 Flare (pipe flare) Permanently formed conical expansion at the pipe end to create a sealed, threaded connection, single flare according to this standard.
4 Design and dimensions
4.1 Pipe outer diameters and wall thicknesses Standard nominal outer diameters of brake pipes: 4.75 mm and 6.0 mm. Permissible wall thicknesses and dimensional tolerances shall comply with the dimensional tables contained within this standard.
4.2 Flare geometry The single flare shall have a cone angle of 45°. All transition radii, flare outer diameter, pipe seating face dimensions and length tolerances shall conform to the specified drawing dimensions. Flare forming shall not cause cracks, splits, folding or local thinning exceeding allowable limits.
5 Materials
Brake pipes shall be manufactured from either: a) Seamless carbon steel tube suitable for subsequent surface coating, or b) Copper-nickel seamless tube conforming to DIN 17664.
6 Manufacturing requirements
6.1 Flare forming Flaring shall be carried out using suitable tooling without damaging the pipe base material. No longitudinal or transverse cracks are permitted on the flare surface. 6.2 Surface condition Pipes shall be free from scale, rust, deep scratches and deformations prior to surface treatment.
7 Strength and tightness requirements
After flaring, samples shall withstand the specified proof pressure without leakage, permanent deformation or fracture. Burst pressure requirements shall be met in accordance with the pipe nominal dimension.
8 Marking
Where agreed between manufacturer and purchaser, brake pipes may be permanently marked with standard reference, nominal size and material identification.
9 Inspection
Inspection includes dimensional check, visual inspection of flares, pressure tightness testing and material verification.
