In the transportation of oil and gas, pipelines are usually selected based on specific transportation needs, environmental conditions, costs and other factors. The following types of pipelines are often preferred in the transportation of oil and gas:

Seamless steel pipe

Features: Seamless steel pipe has a hollow cross-section and no seams around it. Its manufacturing process makes it have high strength and pressure resistance, and can withstand high-pressure oil and gas transportation. At the same time, the inner surface of the seamless steel pipe is smooth and the fluid resistance is small, which is conducive to the smooth transportation of oil and gas and reduces energy loss.

Applicable scenarios: It is often used in high-pressure and high-temperature oil and gas transportation scenarios, such as long-distance trunk line transportation of oil and gas, and risers in deep-sea oil and gas production. For example, in the development of deep-sea oil and gas fields, high-strength seamless steel pipes are usually used for oil and gas transportation risers from the seabed wellhead to the platform to withstand deep-sea high pressure and harsh marine environment.

Straight seam submerged arc welded steel pipe (LSAW)

Features: LSAW Steel Pipe is produced by straight seam welding process, with high weld quality and few welding defects. Its pipe diameter can be made larger, which can meet the needs of large-flow oil and gas transportation. Moreover, the production efficiency of LSAW steel pipe is relatively high, the cost is relatively low, and it has good economy.

Applicable scenarios: It is widely used in the construction of oil and gas pipelines on land and at sea. In large-scale oil and gas pipeline networks on land, such as the West-East Gas Transmission Project, a large number of LSAW steel pipes are used to achieve long-distance and large-flow transportation of natural gas. In marine oil and gas transportation, some submarine pipelines in shallow sea areas also often use LSAW steel pipes.

Spiral Seam Submerged Arc Welded Steel Pipe (SSAW)

Features: SSAW Steel Pipe is manufactured by spiral welding process, and its weld is spiral. This structure enables the weld to better disperse stress when the steel pipe is under pressure, and has high pressure resistance and deformation resistance. At the same time, the production efficiency of spiral seam submerged arc welded steel pipe is high, and it can produce larger diameter steel pipes at a relatively low cost.

Applicable scenarios: It is often used in large-diameter, medium and low-pressure oil and gas pipelines. In some large oil and gas field gathering and transportation systems, the gathering and transportation pipelines from the wellhead to the processing plant, as well as the city gas transmission pipelines, spiral seam submerged arc welded steel pipes are a common choice. For example, many natural gas transmission branch pipelines around the city use SSAW steel pipes.

Composite pipe

Features: Composite pipes are pipes made of two or more different materials through a certain process, usually with the characteristics of corrosion resistance of the inner layer and high strength of the outer layer. For example, the steel-plastic composite pipe is a layer of plastic lined on the inner wall of the steel pipe. It has both the strength of the steel pipe and the corrosion resistance of the plastic, and can effectively prevent the corrosive medium in the oil and natural gas from corroding the pipeline.

Applicable scenarios: It is suitable for transporting oil and natural gas containing corrosive media, such as some high-sulfur and high-salt oil and gas fields. In these special oil and gas transportation environments, composite pipes can extend the service life of the pipeline and reduce maintenance costs. For example, in some offshore high-sulfur oil and gas fields, in order to prevent seawater and oil and gas from corroding the pipeline, composite pipes are used as transportation pipelines.

There are many factors that affect the selection of oil and gas pipelines, covering multiple dimensions such as medium characteristics, environmental conditions, and transportation requirements. The following is a detailed introduction:

Medium characteristics

Physical properties: including the viscosity, density, and freezing point of oil and gas. High-viscosity crude oil may require a larger diameter or a smoother inner wall pipeline to reduce transportation resistance; high-density media may require higher pressure bearing capacity of the pipeline; oil with a high freezing point may require heating or insulation measures during transportation, which will affect the selection of pipeline materials and structures.

Chemical properties: If oil and gas contain corrosive components such as hydrogen sulfide, carbon dioxide, and water, it is necessary to select corrosion-resistant pipeline materials, such as stainless steel, composite pipes, or anti-corrosion treated steel pipes, to prevent the pipeline from being corroded and damaged, ensuring transportation safety and pipeline service life.

Environmental conditions

Geographical environment: When laying pipelines in mountainous and hilly areas, it is necessary to consider the bending and compression resistance of the pipelines. It may be more suitable to use high-strength and flexible steel pipes; in swamps, soft soil foundations and other areas, pipelines are prone to settlement and deformation, and it is necessary to select pipelines with good deformation resistance and corresponding foundation treatment methods; in earthquake-prone areas, it is necessary to consider the seismic performance of the pipeline, and adopt special connection methods and seismic design.

Climate conditions: In cold areas, to prevent the freezing of the medium in the pipeline and the freezing and cracking of the outer wall of the pipeline, it is necessary to insulate the pipeline, select pipeline materials with good insulation performance or take additional insulation measures; in high-temperature areas, it is necessary to consider the heat resistance of the pipeline material to prevent the pipeline from deformation or performance degradation due to high temperature. Pipelines in coastal areas also need to consider problems such as salt spray corrosion, and salt spray corrosion-resistant materials or enhanced anti-corrosion coatings should be selected.

Transportation requirements

Transportation distance: Long-distance transportation generally requires pipelines to have high strength and sealing to reduce energy loss and leakage risks. Large-diameter, high-strength steel pipes are usually selected, such as straight seam submerged arc welded steel pipes (LSAW) or seamless steel pipes. Short-distance transportation can choose more economical pipelines according to specific circumstances, such as spiral seam submerged arc welded steel pipes (SSAW) or plastic pipes.

Transportation pressure and flow: High-pressure and high-flow transportation requires pipelines to have sufficient pressure bearing capacity and a larger pipe diameter. For high-pressure transportation, seamless steel pipes or high-strength LSAW steel pipes are better choices; while for large-flow transportation, the required pipe diameter needs to be calculated according to the specific flow to ensure that the medium can be transported smoothly.

Cost factors

Construction cost: Including the purchase cost, transportation cost, installation cost, etc. of pipeline materials. The cost of pipelines of different materials and specifications varies greatly. For example, the cost of stainless steel pipelines is higher, while the cost of ordinary carbon steel pipes is relatively low. On the premise of meeting the transportation requirements, it is necessary to comprehensively consider the costs of various pipelines and select a cost-effective solution.

Operation and maintenance costs: Although the initial investment of corrosion-resistant and wear-resistant pipelines may be high, the maintenance cost is low during operation. For example, composite pipes can reduce the cost of repair and replacement due to corrosion; while some ordinary steel pipes may need regular anti-corrosion treatment and inspection and maintenance if used in corrosive environments, and the operation and maintenance cost is high.

Regulatory standards

Industry specifications: The oil and gas industry has strict regulations and standards, such as API standards and ASME standards, which have clear requirements for the design, manufacture, installation, and inspection of pipelines. The selection of pipelines must meet these standards to ensure the safety and reliability of pipelines.

Safety regulations: Safety regulations in different regions have different provisions on the safety performance, fire and explosion prevention, and environmental protection of pipelines. For example, in densely populated areas or environmentally sensitive areas, the safety requirements for pipelines are higher, and it may be necessary to choose a safer and more reliable pipeline system and take additional safety protection measures.