In our production line ,we usually find customers prefer E355 seamless cold drawn tube for hydraulic steel tube due to their significant advantages in performance, reliability and safety.
First, E355 seamless cold drawn pipes have a more uniform structure because they have no welds, which is important for hydraulic systems that are subject to high pressure. Then, in terms of strength, cold-drawn or cold-rolled seamless pipes are stronger and suitable for high-pressure environments. Fatigue resistance should also be mentioned, as the frequent pressure changes in hydraulic systems require durable materials. In terms of sealing performance, the inner wall of seamless pipes is smoother, reducing the risk of leakage. It may also be necessary to compare the disadvantages of welded pipes, such as possible defects in welds. In addition, industry standards or certifications may also recommend the use of seamless pipes.
1. Structural integrity advantage
No weld weakness
The seamless pipe is formed in one step by hot rolling or cold drawing process, without longitudinal welds, avoiding the potential cracking risk of welded pipes due to changes in grain structure at the weld.
Under the normal working pressure of 21-35 MPa in the hydraulic system, the burst strength of seamless pipes is 15-25% higher than that of welded pipes of the same specification.
Uniform mechanical properties
The wall thickness tolerance of cold-drawn seamless pipes can be controlled within ±5%, while the wall thickness fluctuation of welded pipes is usually ±10% due to the presence of welding heat affected zone (HAZ).
2. Material performance advantages
High strength and pressure resistance
Common materials:
ST52.4 /ST37.4 (European standard): yield strength ≥355 MPa
AISI 4130 (American standard): tensile strength ≥670 MPa
After cold processing, the yield strength of seamless pipes can be increased by 20-30%, which is particularly suitable for high-pressure scenarios such as engineering machinery.
Excellent fatigue resistance.
In 10^7 pressure cycle tests, the fatigue life of seamless pipes is 3-5 times longer than that of welded pipes, effectively coping with the pulse pressure shock of hydraulic systems.
3. Surface quality and sealing
Inner wall finish
The inner surface roughness of precision cold-drawn seamless pipes can reach Ra ≤0.4 μm, while welded pipes, even after honing, can usually only reach Ra 0.8-1.6 μm.
Geometric accuracy guarantee
4. Process adaptability
Heat treatment controllability
Seamless pipes can be subjected to full-section quenching and tempering treatment (such as quenching + tempering) to ensure uniform material properties, while the hardness fluctuation of the heat-affected zone of welded pipes can reach ±20 HV.
Advantages of deep processing
In subsequent processing such as honing and rolling, the metal flow line continuity of seamless pipes is better, and the surface hardness after rolling can be increased to 350-400 HV, and the wear resistance is significantly enhanced.
