API 5L welded pipes are mainly divided into the following categories:
Classification by welding process:
Electric resistance welded pipe (ERW): It is a welded pipe made by the resistance welding process. During the production process, the steel strip is subjected to a series of forming processes, and the resistance heat generated when the current passes through the weldment is used to heat the contact part of the weldment to make it reach a plastic state or a molten state, and then a weld joint is formed under pressure to obtain a welded pipe. This type of welded pipe has the advantages of high production efficiency and low cost. It is suitable for the production of small and medium-caliber welded pipes and is commonly used in general oil and gas pipelines.
Straight seam submerged arc welded pipe (LSAW): It is made by straight seam welding and submerged arc automatic welding process. First, the steel plate is rolled into a straight seam pipe blank, and then welded at the weld by submerged arc welding. Submerged arc welding is welding under the flux layer. The arc burns under the flux layer, the heat is concentrated, the welding quality is stable, the weld is beautiful, and the mechanical properties are excellent. Straight seam submerged arc welded pipes are suitable for oil and gas pipelines with high pressure and high strength requirements, such as long-distance land oil and gas trunk lines.
Spiral submerged arc welded pipe (SSAW): It is made of hot-rolled steel strip coils as pipe blanks, spirally formed at room temperature, and made by double-sided automatic submerged arc welding or single-sided welding. Its weld is spiral. Compared with straight seam welded pipes, spiral submerged arc welded pipes have higher strength and better toughness under the same pipe diameter and wall thickness, and can withstand greater pressure and external force. Spiral submerged arc welded pipes are widely used in pipelines such as oil, natural gas, and urban gas, especially for large-diameter and high-pressure pipeline projects.
Classification by product specification level:
PSL1 welded pipe: Its chemical composition, mechanical properties and other indicators are relatively basic, and the production and inspection requirements are relatively low. For example, the carbon content of PSL1 is generally not more than 0.26%, and the content of other alloy elements such as manganese content is also specified accordingly. It only needs to meet certain minimum requirements in terms of mechanical properties such as tensile strength and yield strength. PSL1 welded pipes are suitable for some general oil and gas transportation occasions that do not have particularly stringent requirements on pipeline performance, such as short-distance gathering and transportation pipelines inside oil and gas fields.
PSL2 welded pipes: have stricter requirements in terms of chemical composition, mechanical properties, non-destructive testing, etc. For example, the chemical composition control of PSL2 is more precise, and the restrictions on impurity elements are stricter; in terms of mechanical properties, PSL2 has higher requirements for indicators such as yield strength and tensile strength, and requires strict impact performance testing, such as the full-size 0℃ Akv average longitudinal ≥41J, transverse ≥27J (except X80 steel grade). PSL2 welded pipes are mainly used in occasions with extremely high requirements for pipeline safety and reliability, such as long-distance oil and gas transmission trunk lines, submarine oil and gas transmission pipelines, etc.
