Seamless steel pipe (SMLS) is a kind of pipe used to transport fluids. It has the characteristics of high strength and corrosion resistance. It is widely used in petroleum, chemical industry, aviation and other fields. In order to ensure the safety and reliability of seamless steel pipes, strength calculations must be performed to determine their ability to withstand external pressure and stress under working conditions.
Parameters for seamless steel pipe strength calculation:
The strength calculation of seamless steel pipes needs to consider the following parameters:
1. The outer diameter and inner diameter of the pipe determine the cross-sectional area and volume of the pipe;
2. The wall thickness of the pipe determines the quality and load-bearing capacity of the pipe;
3. The length of the pipe determines the total mass and load-bearing capacity of the pipe;
4. The material of the pipe, including the strength and toughness of steel, determines the tensile strength, yield point, shear strength, bending strength and fracture toughness of the pipe.
The formula for calculating the strength of seamless steel pipe:
The strength calculation of seamless steel pipe can use the following formula:
1. Cross-sectional area of the pipe: A=π/4×(D²-d²)
Among them, A is the cross-sectional area, D is the outer diameter, and d is the inner diameter.
2. Volume of the tube: V=π/4×L×(D²-d²)
Among them, V is the volume, L is the length, D is the outer diameter, and d is the inner diameter.
3. The mass of the tube: m=ρ×V
Among them, m is the mass, ρ is the density of steel, and V is the volume.
4. Tensile strength of pipe: σt=F/A
Among them, σt is the tensile strength, F is the force, and A is the cross-sectional area.
5. Yield point of pipe: σy=F/A
Among them, σy is the yield point, F is the force, and A is the cross-sectional area.
6. Shear strength of pipe: τ=F/A
Among them, τ is the shear strength, F is the force, and A is the cross-sectional area.
7. Bending strength of pipe: σb=M/W
Among them, σb is the bending strength, M is the bending moment, and W is the section modulus.
8. Fracture toughness of pipe: Kc=σf×sqrt(πa)
Among them, Kc is the fracture toughness, σf is the cracking stress, and a is the crack length.
Examples of seamless steel pipe strength calculation:
For example, for a seamless steel pipe with an outer diameter of 100mm, an inner diameter of 80mm, a wall thickness of 10mm, and a length of 10m, using Q235B steel, how should the strength be calculated?
1. Calculate the cross-sectional area: A=π/4×(100²-80²)=2513.27mm²
2. Calculate volume: V=π/4×10×(100²-80²)=628316.48mm³
3. Calculated mass: m=7.85×10⁻⁶×628316.48=4.94kg
4. Calculate tensile strength: σt=F/A
Assuming that the force endured is 100kN, then σt=100×10³/2513.27=39.78MPa
5. Calculate the yield point: σy=F/A
Assuming that the force endured is 80kN, then σy=80×10³/2513.27=31.82MPa
6. Calculate shear strength: τ=F/A
Assuming that the force endured is 50kN, then τ=50×10³/2513.27=19.90MPa
7. Calculate bending strength: σb=M/W
Assuming the bending moment is 200kN·m, then W=1/6×(100⁴-80⁴)÷(100×10⁻³)=77491.56mm³
Then σb=200×10³×50/77491.56=258.26MPa
8. Calculate fracture toughness: Kc=σf×sqrt(πa)
Assuming that the cracking stress is 80MPa and the crack length is 2mm, then Kc=80×sqrt(π×2)=89.98MPa·sqrt(mm)
Conclusion:
By calculating the strength of seamless steel pipes, its ability to withstand external pressure and stress under working conditions can be determined. In actual use, it is necessary to select appropriate materials and sizes according to specific working conditions and application fields to ensure the safety and reliability of seamless steel pipes.
Read more: How to Calculate the Weight of Carbon Steel Tube?
