Q345D seamless steel pipe can be divided into hot-rolled pipe, cold-rolled pipe, cold-drawn pipe, and extruded pipe, depending on the production method. Q345D is composed of Q + a number + a quality grade symbol. The steel grade of Q345D seamless steel pipe begins with “Q,” representing the yield point of the steel. The following number indicates the yield point value in MPa. For example, Q345 indicates carbon structural steel with a yield point (Rel) of 345 MPa.
Chemical composition of Q345D seamless steel pipe: C: ≤0.18; Si: ≤0.50; Mn: ≤1.70; P: ≤0.030; S: ≤0.025; Nb: ≤0.07; V: ≤0.15; Ti: ≤0.20; Cr: ≤0.30; Ni: ≤0.50; Cu: ≤0.30; N: ≤0.012; Mo: ≤0.10; ALS: ≥0.015.
Impact test of Q345D seamless steel pipe: -20℃: ≥34.
Commonly used standards for Q345D seamless steel pipe:
1. Seamless steel pipe for structural use (GB8162-2018) is used for general structures and mechanical structures.
2. Seamless steel pipe for fluid transportation (GB8163-2018) is used for transporting fluids such as water, oil, and gas.
3. Seamless steel tubes for low and medium pressure boilers (GB3087-2018) are high-quality carbon structural steel hot-rolled and cold-drawn (rolled) seamless steel tubes used in the manufacture of superheated steam pipes, boiling water pipes, and locomotive boiler superheated steam pipes and arch brick pipes for various structural low and medium pressure boilers.
4. High-pressure seamless steel tubes for fertilizer equipment (GB6479-2000) are high-quality carbon structural steel and alloy steel seamless steel tubes suitable for chemical equipment and pipelines with operating temperatures of -40~400℃ and operating pressures of 10~30MPa.
Q345D seamless steel tubes have a wide range of applications. General-purpose seamless steel tubes are rolled from ordinary carbon structural steel, low-alloy structural steel, or alloy structural steel, and are produced in large quantities.
1. Q345D seamless steel pipes are mainly used as pipelines for transporting fluids or as structural components.
2. Q345D seamless steel pipes are supplied in three categories according to their intended use:
a. Q345D seamless steel pipes are supplied based on chemical composition and mechanical properties;
b. Q345D seamless steel pipes are supplied based on mechanical properties.;
c. Q345D seamless steel pipes are supplied based on hydrostatic testing. Steel pipes supplied according to categories a and b, if used to withstand liquid pressure, must also undergo hydrostatic testing.
3. Seamless steel pipes for special purposes include seamless steel pipes for boilers, chemical and power industries, geological applications, and petroleum applications, among others.
Post time: Apr-17-2026