What is API 5L PSL1 carbon steel pipe?
The API 5L PSL1 carbon steel pipe is a carbon steel pipe manufactured in accordance with Product Specification Grade 1 (PSL1) in the API 5L standard of the American Petroleum Institute, and is mainly used for transporting fluids such as oil, natural gas and water.
This type of steel pipe belongs to the basic grade, featuring excellent mechanical properties and chemical stability, and is suitable for medium and low-pressure conveying systems in general industrial environments.
The manufacturing methods of API 5L PSL1 carbon steel pipe are mainly divided into two types: seamless pipe (SMLS) and welded pipe (ERW, LSAW, SSAW, DSAW).
Main chemical components (taking Grade B as an example)
Chemical composition comparison table
| Chemical composition | Seamless pipe | Welded pipe |
| C（max） | 0.28% | 0.26% |
| Mn（max） | 1.20% | 1.20% |
| P（max） | 0.03% | 0.03% |
| S（max） | 0.03% | 0.03% |
| V（max） | a,b | b |
| Nb（max） | a,b | b |
| Ti（max） | b | b |
| Note | a.NB + V ≤ 0.06%, b.Nb + V + Ti ≤ 0.15% |
Among them, for every 0.01% reduction in the carbon content of the PSL1 carbon steel pipe, the allowable manganese content is 0.05% higher than the specified maximum concentration. For grades ≥ L245 or B but ≤ L360 or X52, the maximum can reach 1.65%. For grades > L360 or X52 but < L485 or X70, the maximum can reach 1.75%. For grade L485 or X70, the maximum can reach 2.00%. It may also contain Cu, Ni, Cr and Mo, with Cu≤Ni≤0.50%. Cr 0.50% or less; MO≤0.15%.
Mechanical performance
The mechanical properties of PSL1 vary depending on different grades:
Grade B: Yield strength ≥ 35,500 psi, tensile strength ≥ 60,200 psi, elongation ≥23-28%, and the minimum tensile strength of the weld seam of the welded pipe is 60,200 psi.
X42: Yield strength ≥ 42,100 psi, tensile strength ≥ 60,200 psi, elongation ≥28%, the minimum tensile strength of the weld seam of the welded pipe is 60,200 psi.
X46-X70: The yield strength and tensile strength increase with the grade. For example, X70: The yield strength is ≥ 70,300 psi and the tensile strength is ≥ 82,700 psi.
Inspection and Testing
Compared with PSL2, PSL1 has fewer testing requirements: generally, it does not need to conduct impact (Charpy) tests, nor does it enforce non-destructive testing (NDT). The mechanical and chemical properties of PSL1 are generally the standard minimum limits and are not suitable for extreme conditions and high-specification pipelines.
Application scenarios
Pipeline systems for transporting oil, natural gas, water and certain desalinated water, etc.
It is commonly used in normal or medium-temperature conveying pipelines in power plants, refineries and chemical plants.
PSL 1 is usually chosen because the structural safety requirements are not high and the budget is limited, but it is not suitable for high pressure, high impact or corrosive environments (PSL 2 or special materials are recommended in this case).
Summary
API 5L PSL1 carbon steel pipe is a regular industrial conveying pipe with stable performance and moderate cost, complete specifications (seamless and various welded forms), suitable for oil, gas and water conveying projects in general environment. For higher safety, compliance with strict regulations, or use in harsh environments, PSL 2 or other project specification pipes are recommended.