What are the Types Of API 5L Pipes

An API 5L pipe is manufactured by adhering to the specifications laid down by the International Organization for Standardization (ISO) 3183. It standardizes the criteria for the materials, equipment and offshore structures for petrochemical, petroleum and natural gas industries. PSL 1 and PSL 2 are the two Product Specification Levels that have been recognized by the technical committee which is mostly used in Oil and Gas Industries.

When we distinguish API 5L PSL 1 and PSL 2, we learn it from this 5 aspects: in Chemical Properties; in Mechanical Properties; in Manufacturing; in Inspections and defect repair; in certification & tractability.

Grade Range A25 through X70 B through X80
Size range 0.405″ through 80″ 4.5″ through 80″
Type of ends Plain end, Threaded end, Plain end
Bevelled end special coupling pipes
Seam welding All methods: All methods:
continuous welding except continuous welding
limited to A25 and laser welding
Electric welds: welder frequency No minimum kHz minimum 100
Heat treatment of electric welds Required for grades >X42 Required for all grades
(B through X80)
Chemistry: Max C for Seamless pipe 0.28% for grades ≥ B 0.24%
Chemistry: Max C for Welded pipe 0.26% for grades ≥ B 0.22%
Chemistry: Max P 0.030% for grades ≥ A 0.03%
Chemistry: Max S 0.03% 0.02%
Carbon equivalent: Only when purchaser Maximum required
specifies SR18 for each grade
Yield strength, maximum None Maximum for each grade
UTS (Ultimate Tensile Strength) None Maximum for each grade
Fracture toughness None required Required for all grades
Non-destructive inspection Only when purchaser SR4 mandatory
of Seamless specifies SR4
Repair by welding of pipe body Permitted Prohibited
plate,and skelp
Repair by welding of weld seams Permitted by agreement Prohibited
without filler metal
Certification Traceable only until Certificates (SR15.1)
all tests are passed mandatory
Traceability Traceable only until Traceable after completion
all tests are passed of tests
unless SR15 is specified (SR15.2) mandatory

First, what is PSL stands for?
An API 5L line pipes manufactured in two varieties PSL 1 and PSL 2. But what is PSL stands for? PSL is short for Product Specification Levels. Pipes are used in different types of environment such as corrosive and non-corrosive.

If pipes used in the severe corrosive environment required material that can withstand such process condition. If pipe used in a high-pressure condition required weld seam withstand such requires. On other hands for normal services, a standard quality level pipe will meet the purpose. That’s why there are two product levels. We can choose according to the condition which pipe used and be economical.

Second, from which aspects?
In API 5L specification, what are the main differences between API 5L PSL 1 & PSL 2? We compare them in these 5 aspects.

1. The difference between API 5L PSL1 and PSL2 Pipes – Chemical Properties
① Different steel grade.
② Three elements change when requirements change from API 5L PSL1 and PSL2.
The first element is Carbon. 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%.
The second element is Phosphorus. For PSL1 pipe, Maximum Phosphorus is 0.03% for the grade A & higher. For all grades of PSL2 pipes, maximum Phosphorus is 0.025%. So, the only difference is a grade lower than A.
The third element is Sulphur. For PSL1 pipe, Maximum Sulphur is 0.03%. For PSL2 pipes maximum Sulphur is 0.015%.

2. The difference between API 5L PSL1 and PSL2 Pipes – Mechanical Properties
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.

3. The difference between API 5L PSL1 and PSL2 Pipes – Manufacturing
① Grade Range
For PSL 1, steel grade range from A25 to X70; For PSL 2 steel grade range from Grade B to X120.
But for LSAW of our company, PSL 2 range from Grade B to X80.

② Size range
For PSL 1 its size range from 0.405″ to 80″. For PSL 2 its size range from 4.5″ to 80″.
But for LSAW pipe, its ranges from 16″ to 60″.

③ Type of pipe ends
For PSL1 pipes are available in different types of end such as Plain end, Threaded end, Bevelled end, special coupling pipes. For PSL2 pipes are available in only Plain End. (if no other agreements.)
For LSAW pipe end please see the article “LSAW Steel Pipe End”

④ Welding method
All kinds of welding method are acceptable to manufacture PSL1; however, continuous welding is limited to Grade A25. For PSL2 welded pipes, except continuous welding and laser welding, all other welding methods are acceptable.
And 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.

4. Inspection and Defect Repair
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 skim 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.

5. Certification & Traceability
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.

In short, PSL1 pipes are standard quality pipe for normal services and PSL2 pipes are higher quality pipe than PSL1. PSL 1 is a loose standard quality for line pipe, whereas PSL 2 contains additional testing requirement, stricter chemical physicals, along with different ceiling limits of mechanical properties, and require Charpy impact testing conditions.

From these 5 aspects we can distinguish API 5L PSL1 and PSL2. This tells the exact requirements for API 5L standard pipe.

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