An API 5L line pipes manufactured in two varieties PSL 1 and PSL 2. But what is PSL? PSL stands for Product Specification Levels. PSL stands for Product Specification Levels.
Pipes are used in different type of environment such as corrosive and non-corrosive. Pipes used in severe corrosive environment required material that can withstand such process condition. On other hands for normal services, a standard quality level pipe will also serve the purpose.
The difference between PSL1 and PSL2 pipes are as follows;
Difference in Chemical Properties
Difference in Mechanical Properties
Difference in Manufacturing
Difference in Inspection and Defect Repair
Difference in Certification & Traceability
Three elements change when requirements change from PSL1 to PSL2.
Maximum Carbon for Seamless PSL1 pipe is 0.28% for the grade B & higher. For all grades of PSL2 pipes maximum carbon is 0.24%.
Similarly, for welded PSL1 pipe Maximum Carbon is 0.26% for the grade B & higher. For all grades of PSL2 welded pipes maximum carbon is 0.22%.
For PSL1 pipe, Maximum Phosphorus is 0.03% for the grade A & higher. For all grades of PSL2 pipes, maximum Phosphorus is 0.03%. So, the only difference is a grade lower than A.
For PSL1 pipe, Maximum Sulphur is 0.03%. For PSL2 pipes maximum Sulphur is 0.02%.
Other than these three elements, for PSL2 pipe meeting, the Carbon equivalent is mandatory whereas for PSL1 pipe it is only required if the purchaser has specified SR18. SR18 means Supplementary Requirement No.18.
For PSL2 pipe there is a limit on Maximum Yield & Ultimate Tensile Strength whereas for PSL1 pipe meeting the minimum requirements are sufficient. The second requirement that is mandatory for PSL2 pipe is Fracture toughness which is not required for the PSL1 pipe.
Here in this table, ou can see the differences between PSL1 & PSL2 Pipes Manufacturing. PLS1 pipes are available in grade A25 through X70 whereas PSL2 pipes are available in Grade B through X80.
PSL1 pipes are available through size 0.405” to 80” whereas smallest diameter pipe available in PSL2 is 4.5” and the largest diameter is 80”.
PSL1 pipes are available in different types of end such as Plain end, Threaded end, Bevelled end, special coupling pipes whereas PSL2 pipes are available in only Plain End.
All kinds of welding method are acceptable to manufacture PSL1; however, continuous welding is limited to Garde A25. For PSL2 welded pipes, except continuous welding and laser welding, all other welding methods are acceptable.
For electric weld welder frequency for PSL2 pipe is minimum 100kHz whereas there is no such limitation on the PLS1 pipe. Heat treatment of electric welds is required for all Grades of PSL2 pipes whereas for PSL1 pipe, it is required for grades higher than X42.
Non-destructive inspection of a seamless pipe is mandatory for PSL2 pipe whereas for PLS1 pipe it is supplementary requirements.
Repair of pipe body plate and skelp by welding is not allowed in PSL2 pipes whereas it is allowed in PSL1 pipes. Similarly, weld repair without filler metal is not allowed in PSL2 pipes whereas it is allowed with purchaser's permission in PSL1 pipes.
For PSL1 pipes, Traceability & Certification is not required beyond the point it passes all the required test whereas, for PSL2 pipes, Traceability & Certification is mandatory.
This is all about the difference between PSL1 and PSL2 pipes.
In short PSL1 pipes are standard quality pipe for normal services and PSL2 pipes are higher quality pipe than PSL1.