Calculation Method of Seamless Steel Pipe Wall Thickness and Bearing Pressure

For carbon seamless steel pipes, if the outer diameter and wall thickness are known, it is required to calculate how much pressure it can withstand; or if the outer diameter and pressure are known, it is required to calculate its economical and applicable wall thickness. The above two situations are often encountered by our designers in our work. Here, we will provide you with the calculation formula:

(1) The calculation method of known seamless steel pipe outer diameter specifications and wall thickness to withstand pressure (the tensile strength of different steel pipes is different)
Pressure = (wall thickness * 2 * steel pipe material tensile strength) / (outer diameter * coefficient)

(2) The calculation method for calculating the wall thickness of the known seamless steel pipe outer diameter and pressure:
Wall thickness=(pressure*outer diameter*factor)/(2*tensile strength of steel pipe material)

(3) Expression method of steel pipe pressure coefficient:
a. Pressure P<7Mpa coefficient S=8;
b. 7<steel pressure P<17.5 coefficient S=6;

c. Pressure P>17.5 coefficient S=4.

Suppose the tensile strength of the material is σ, the pressure is P, and the outer diameter of the tube is D;
Pipe wall thickness δ= (P*D)/(2*σ/S)

Where S is the safety factor;
Pressure P is less than 7MPa, S=8; P is between 7 and 17.5MPa, S=6; P is greater than 17.5MPa, S=4;

For example: How much pressure can the φ16*3 seamless steel pipe (20#steel) bear?
Our first step is to choose the safety factor S=6; choose 20# steel with a tensile strength of 410MPa;

φ16*3 seamless steel pipe can withstand pressure:
P= (2*σ/S*δ)/D
=(2*410/6*3)/16
=25.6MPa
--------
This value> 17.5MPa
Therefore, the safety factor takes S=4 for the second time

φ 16*3 seamless steel pipe can withstand pressure:
P= (2*σ/S*δ) /D
=(2*410/4*3)/16
=38.4MPa

Real examples from our design:

1. For a project, the GL heater mixing pipe uses φ76*4 seamless steel pipe (20# steel):
Our first step is to choose the safety factor S=6; choose 20# steel with a tensile strength of 410MPa;

The pressure that the steel pipe can withstand
P= (2*σ/S*8) /D
=(2*410/6*4)/76
=7.2MPa (this value is between 7~17.5MPa)

Conclusion: φ76*4 seamless steel pipe can withstand the steam pressure of this project at 2.2MPa, so don’t worry.

2. For the same project mentioned above, φ18*2.5 seamless steel pipe is initially selected for the heat exchange tube of the GL heater, instead of the usual φ18*2 seamless steel pipe (20# steel). So, can the φ18*2 seamless steel pipe withstand the steam pressure of 2.2MPa?
Our first step is to choose the safety factor S=8; choose 20# steel with a tensile strength of 410MPa;

The pressure that the steel pipe can withstand
P= (2*σ/S*δ)/D
=(2*410/8*2)/18
=11.4MPa
------- This value> 7MPa
 

Therefore, the safety factor takes S=6 for the second time;

The pressure that the steel pipe can withstand
P= (2*σ/S*8) /D
=(2*410/6*2)/18
=15.2MPa
 

It can be seen that the φ18*2 seamless steel pipe can bear pressure of 15.2MPa, and the steam pressure in this project is 2.2MPa. For this working condition, φ18*2.5 does not have to be used (the wall thickness is increased, the pressure bearing capacity will be higher).

As a carbon steel pipe manufacturer, Permanent Steel Manufacturing Co.,Ltd specializes in the production and supply of seamless steel pipes, welded steel pipes, hollow sections, stainless steel pipes, pipe fittings, etc., with more than ten years of production experience. (Fluid pipe/Boiler pipe/Fire pipe/Line pipe/Structural pipe)

Article source: https://article-realm.com/article/Finance/18124-Calculation-Method-of-Seamless-Steel-Pipe-Wall-Thickness-and-Bearing-Pressure.html