Carbon steel spiral steel pipe pressure grade analysis

The pressure ratio of spiral steel pipe on gas pipelines also tends to decrease gradually. The pipe diameter, pressure, and pressure ratio need to be optimized and compared. When the output is determined, the pipe diameter, pressure, and pressure ratio are determined by optimization. If higher pressure is selected and the steel strength grade is too low, the wall thickness will be too large, which will bring difficulties to many links such as pipe making, on-site welding, and transportation, and even difficult to achieve.

At present, thick-walled spiral pipes are mostly used for fluid transmission pipelines. The transmission pressure of pipeline media has gradually increased in recent years, especially on gas pipelines. This is because increasing the transmission pressure within a certain range will increase economic benefits. Taking the gas pipeline as an example, under the condition of constant output, as the transmission pressure increases, the density of the gas increases and the flow rate decreases, thereby reducing friction.

The demand for production has promoted the improvement of steel grades. The so-called pressure ratio refers to the ratio of the inlet pressure to the outlet pressure. A reduction in the pressure ratio means that the entire line is operating at a higher pressure, which can also reduce energy consumption. In the early days, the pressure was mostly 1.6, and later it dropped to 1.4. In recent years, some foreign gas pipelines have adopted a pressure ratio of 1.25. Of course, as the pressure ratio decreases, the number of compressor stations will increase, and thus the investment will increase.