The difference between 20# seamless steel pipe and 20G seamless steel pipe
20# seamless steel pipe is used for structural pipe, liquid pipe, low and medium pressure boiler tube. 20G seamless steel pipe is applied for high pressure boiler tubes.
Except for same carbon content (0.17-0.24), 20G seamless steel pipe has also some trace element suitable for boiler pressure vessel, 20G also focus on its mechanical properties, such as bending, impact and tensile strength. In addition, 20# implement GB699 standard, but 20G implement GB713, and changed to Q245R in 2008.
The characteristics and scope of application of 20# seamless steel pipe:
Higher strength more than 15# steel, less quenching, no temper brittleness; High plasticity, good weld-ability; Easy to crack when outside shape is required strictly.
Chemical component and mechanical properties of 20# seamless steel pipe:
| Chemical component | Mechanical properties | ||
| C | 0.17-0.24 | Tensile strength | ≥410 |
| Si | 0.17-0.37 | Yield strength | ≥245 |
| Mn | 0.35-0.65 | Elongation | ≥25 |
| S | ≤0.035 | Reduction of area | ≥5 |
| P | ≤0.035 | Hardness without heat treatment | ≤156HB |
| Cr | ≤0.25 | ||
| Ni | ≤0.25 | ||
| Cu | ≤0.25 | ||
20G seamless steel pipe is one of boiler tubes. Its manufacturing method is same as seamless steel pipe, but there are strictly requirements for steel grade used to produce steel pipes. 20G high pressure boiler tubes are often applied in high temperature and high pressure conditions. The tubes in smoke and steam with high temperature are easy to rust and corrode, and are required to have high durability high corrosion resistance and good tissue stability.
20# Seamless steel pipe