1. Long distance oil pipelines

Main pipeline:

The diameter is usually between Φ 600 and Φ 900mm. For example, in some large cross-border or cross regional oil pipelines, LSAW Steel Pipes with diameters of Φ 711mm or Φ 813mm are more common. This is because larger pipe diameters can transport large amounts of crude oil at relatively lower pressures during long-distance transportation, reducing energy loss. According to the Darcy Weisbach formula in fluid mechanics, \ (h3=f \ frac {L} {D} \ frac {v ^ 2} {2g} \) (\ (h3 \) is the head loss along the way\ (f \) is the coefficient of friction\ (L \) is the length of the pipeline\ (D \) is the pipe diameter\ (v \) is the flow velocity\ (g \) is the acceleration due to gravity. Under a constant flow rate, increasing the pipe diameter (D \) can reduce the head loss along the way, thereby reducing energy loss during transportation.

Meanwhile, the strength and stability of steel pipes within this diameter range can also meet the requirements for long-distance transportation. In terms of design pressure, the general design pressure for oil pipelines is around 4-8 MPa. LSAW steel pipes with diameters ranging from Φ 711mm to Φ 813mm and wall thicknesses of 10-16mm (determined according to different steel grades and transportation conditions) can withstand such pressure.

Branch pipeline:

The diameter is relatively small, generally ranging from Φ 406.4 to Φ 600mm. These branch pipelines are mainly used to transport crude oil from the main line to terminal facilities such as refineries or oil storage facilities. A smaller pipe diameter can accommodate lower flow demands and is relatively low in construction cost and difficulty. For example, in the branch pipelines connecting oil pipelines and refineries, LSAW steel pipes with a diameter of Φ 406.4mm or Φ 508mm are more suitable, with a design pressure of 3-6 MPa and a wall thickness of around 8-12mm.

2. Long distance gas pipelines

Main pipeline:

The diameter requirement is relatively large, usually ≥ Φ 900-1200mm, commonly including Φ 1016mm, Φ 1219mm, Φ 1422.4mm, etc. This is because the density of natural gas is much lower than that of crude oil, and at the same mass flow rate, the volumetric flow rate of natural gas is much larger. According to the gas transport equation \ (Q=vA \) (where \ (Q \) is the volumetric flow rate\ (v \) is the flow velocity\ (A \) is the cross-sectional area of the pipeline. In order to transport a large amount of natural gas, a larger pipeline cross-sectional area, i.e. a larger pipe diameter, is required. For example, in large-scale natural gas transmission projects such as the West East Gas Pipeline, LSAW steel pipes with a diameter of Φ 1016mm are extensively used.

The design pressure of gas transmission trunk lines is relatively high, generally ranging from 8-12 MPa or even higher. For steel pipes with diameters ranging from Φ 1016mm to Φ 1422.4mm, the wall thickness is usually around 14-22mm to withstand high pressure. Meanwhile, a larger pipe diameter can also reduce the flow rate of gas, decrease frictional losses, and improve transportation efficiency.

Branch pipeline:

The diameter range is generally between Φ 600 and Φ 900mm. These branch pipelines are used to transport natural gas from the main line to urban gate stations or small industrial users. For example, in the branch pipelines that transport natural gas to urban gas gate stations, LSAW steel pipes with a diameter of Φ 711mm or Φ 813mm are commonly used, with a design pressure of around 6-10MPa and a wall thickness of 10-16mm.

3. Internal gathering and transportation pipelines in oil and gas fields

Pipeline from oil well to metering station:

The diameter is relatively small, generally ranging from Φ 200 to Φ 406.4mm. In the early stage of oil and gas field exploitation, the flow rate of crude oil or natural gas produced by oil wells is relatively small and does not require a large pipe diameter. For example, in some small oil well to metering station gathering and transportation pipelines, LSAW steel pipes with a diameter of Φ 219mm or Φ 323.9mm can meet the requirements, with a design pressure of 2-4MPa and a wall thickness of 6-10mm.

Pipeline from metering station to oil or gas gathering station:

The diameter may be between Φ 406.4 and Φ 600mm. As crude oil or natural gas accumulates, the flow rate gradually increases, requiring a corresponding increase in pipe diameter. For example, for the pipeline from the metering station to the oil gathering station, LSAW steel pipes with a diameter of 508mm are commonly used, with a design pressure of 3-5MPa and a wall thickness of 8-12mm.

The connecting pipeline from the oil or gas gathering station to the export pipeline:

The diameter usually needs to match the export pipeline, usually around Φ 600- Φ 900mm, in order to smoothly transport oil and gas to the export trunk line. For example, in the pipeline connecting the oil gathering station and the oil transmission trunk line, LSAW steel pipes with a diameter of Φ 711mm can effectively transfer oil and gas, and their design pressure and wall thickness are determined according to the requirements of the export pipeline and actual working conditions.