Precision cold-drawn seamless steel pipes are treated by black or gray phosphating, and precise hydraulic seamless steel pipes are treated by sealing and rust-proof of phosphating steel pipes.


A compact phosphating layer is formed on the inner and outer surfaces of precise hydraulic seamless steel tubes, which can effectively prevent oxidation by rust-proof treatment. Therefore, the anti-rust performance of steel pipe is excellent, and through the phosphating of the steel pipe surface (layer) to form a microporous phosphating film, can effectively adsorb the paint on the steel pipe surface, effectively prevent the paint from falling off, is an ideal product used in the field environment.


The steel pipes used in the hydraulic system are mainly stainless steel seamless pipes and general seamless pipes. Although stainless steel seamless tubes have excellent mechanical properties, they are not widely used because of their high price and low precision. Although ordinary seamless steel tubes are commonly used, their mechanical properties are poor and their accuracy is low. Before use, they usually carry out a series of welding, assembly, pickling, alkali washing, water washing, long-term oiling, leakage testing and process. Complex, time-consuming, unreliable materials and the inability to completely remove residues in pipes have become the main dangers of failure of the entire hydraulic system at any time.  According to statistics, 70% of the faults in hydraulic system are caused by this reason.


DIN2391 series of high precision bright seamless steel pipes are special pipes for hydraulic system. It has the following six advantages:
1. There is no oxide layer on the inner and outer walls of steel pipes, which can be directly installed in the hydraulic system.
2. High pressure resistance, no leakage.
3. High accuracy.
4. High gloss.
5. Cold bending does not deform.
6. Enlarged, flat, without cracks.