Phosphate Precision Steel Tubes / High Precision Steel Tubes / Cold Drawn Steel Tubes

The finished bright annealing NBK steel tubes are used for black phosphating. The phosphate processing uses imported chemical fluids to form a black film on the inner and outer surface of the steel tubes. The anti-rust oil is absorbed using a micro pore on the black film in order to prevent rust.
Dimension range: outer diameter- 3-89mm, wall thickness- 0.4-10mm
Standard specifications: DIN2391, EN10305-1, SAE J524, JIS G3445
Steel grade: ST37.4, ST45, ST52.4, E235, E255, E355, C1010, C1020
Main Features: clean and smooth outer and inner surface, shining black color, excellent rust resistant properties
These cold drawn precision steel tubes are used in hydraulic systems, ship building, machinery and more.

Process Description
We utilize NBK high precision steel tubes with a bright finish, and seamless stainless steel material for the development of these tubes. These steel pipes are coated on the interior and exterior with an imported, environmentally friendly phosphate solution. This phosphate solution is black and forms a protective film, allowing the absorption of phosphate rust through micro pores in the film oil for rust treatment. Dust covers at both ends of the cold drawn tube undergo the same treatment.

Main Features
These cold drawn precision steel tubes are steel black in color, with an even surface. They are both consistent and strong, with an aesthetically pleasing appearance, and an excellent rust resistant performance.

Main Purpose
Cold drawn black phosphate precision steel tubes are widely used in hydraulic systems with steel pipes, and ferrule connectors (pipe joints) that match.

Main Materials and Mechanical Properties
We use raw materials from Shanghai Baosteel, including ST35, ST37.4 (10 #), ST45 (20 #), ST55 (35 #), CK45 (45 #), and ST52.4 (16MN).
The steel precision pipes utilize excellent mechanical properties, as well as an excellent performance process. The steel can easily withstand high pressures and shocks, making it ideal for use in hydraulic machinery and auto part industries. Cold-formed steel can be formed at angle deformation, flaring, and flattening, with no cracks or bending deformation processes.
Surface quality: the inner and outer surfaces are clean, with no oxide layer, and no cracks, folding, rolling, scarring, separations or hairlines.
The steel heat treatment method and manufacturing method used both correspond to the inner and outer surfaces (ex, scratches, bumps and grooves), but go no deeper than 0.025mm, a requirement that is higher than the standard DIN2391.

Pipe corrosion packaging and transportation: The pipes are steel, coated in an anti-rust oil, and both ends are capped in plastic. The inner layer of packaging is a plastic film, the outer is linen or wooden packaging.
Note: a steel quality certificate will be issued.

How do we ensure the quality of these automotive steel pipes?
1. We use high quality raw materials. All raw materials are supplied from internationally known steel plants.
2. Each batch of raw material is checked for both chemical and mechanical properties, according to specifications.
3. During the cold drawing process, our inspectors check every bundle three times: once at the beginning of the process, once during the middle, and finally, at the end of the cold drawing process.
4. During the final heat treatment, every bundle has the surface checked, as well as mechanical properties through sampling.
5. Non-destructive testing machinery and manual inspection ensure the 100% quality rate.