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# Pressure calculation of cold drawn seamless tubing

Cold drawn seamless tubing refer to seamless steel pipes with high dimensional accuracy and good surface finish used in mechanical structures and hydraulic equipment. The use of cold drawn seamless tubing to manufacture mechanical structures or hydraulic equipment can greatly save machining hours, improve material utilization, and help improve product quality.

Pressure calculation formula

1) Knowing the outer diameter and wall thickness of the cold drawn seamless tubing, the pressure calculation method:
Different tensile strength of steel pipe with different pressure = (wall thickness * 2 * tensile strength of steel pipe material) / (outer diameter * coefficient)

2) Calculation method for wall thickness of known cold drawn seamless tubing outer diameter and pressure:
Wall thickness = (pressure * outer diameter * coefficient) / (2 * tensile strength of cold drawn seamless tubing material)

3) Representation method of pressure coefficient of cold drawn seamless tubing:
Pressure P<7Mpa, coefficient S=8
7 Pressure P>17.5, coefficient S=4

For example:
DN=10MM, the wall thickness is 3mm, the safety factor is S=6, the tensile strength of 20 steel is 410MPa
Let the tensile strength of the cold drawn seamless tubing be σ, the pressure be P, and the outer diameter of the pipe D;
Cold drawn seamless tubing wall thickness δ=(P*D)/(2*σ/S); where S is the safety factor;
Therefore, the pressure that the pipe can withstand P=(2*σ/S*δ)/D
=(2*410/6*3)/(10+6)
=26.25MPa> set 17.5
Therefore, the safety factor is taken as S=4
Therefore, the pressure P=(2*σ/S*δ)/D that the cold drawn seamless tubing can bear
=(2*410/4*3)/(10+6)
=39.375MPa

4) Calculation formula of water pressure value
Bernoulli equation: p+ρgz+(1/2)*ρv^2=C
where p, ρ, v are the pressure, density and velocity of the fluid, respectively; z is the vertical height; g is the acceleration of gravity; C is a constant