API 5L PSL1 vs PSL2: what changes and when to specify PSL2
Both are line pipe to the same standard, but PSL2 adds tighter chemistry, upper strength limits, mandatory impact testing and full traceability. Here is what that means for your order.
What PSL means
API 5L, the specification for steel line pipe, defines two product specification levels. PSL1 is the standard level. PSL2 is a higher level with extra mandatory requirements on chemistry, mechanical properties, testing and traceability. Both share the same basic grades and dimensions, so the difference is not size or strength class but how tightly the pipe is controlled and checked.
The main differences
| Requirement | PSL1 | PSL2 |
|---|---|---|
| Grades | A, B and X42 to X70 | B and X42 to X80, plus X90 to X120 in some delivery conditions |
| Delivery condition in the grade name | Not required | Required: suffix R, N, Q or M, for example X52N |
| Chemistry | Maximum carbon, manganese, phosphorus and sulphur | Lower maximums, plus carbon equivalent limits for weldability |
| Yield and tensile strength | Minimums only | Minimums and maximums, with a maximum yield-to-tensile ratio (typically 0.93) |
| Charpy impact testing | Not mandatory | Mandatory, with minimum absorbed energy |
| Traceability | Limited | Full traceability by heat and test unit |
| Sour and offshore service | Not covered | Annex H (sour) and Annex J (offshore) apply to PSL2 pipe only |
Reading a PSL2 grade name
PSL2 grades carry a letter showing how the pipe was made: R for as-rolled, N for normalized, Q for quenched and tempered, and M for thermomechanically rolled. X65Q, for example, is a PSL2 grade with a specified minimum yield strength of 65,000 psi (448 MPa), quenched and tempered. Not every combination exists, and the higher grades are only made in Q or M condition, so check availability before fixing the suffix in a specification.
When to specify PSL2
- Gas pipelines and high-pressure hydrocarbon lines
- Sour service with hydrogen sulphide, which requires Annex H and therefore PSL2
- Offshore pipelines, under Annex J, which is also PSL2 only
- Low design temperatures, where impact toughness matters
- Any project whose client specification calls for it, which is common for oil and gas work in the GCC
PSL1 remains a sensible choice for water, utility and low-pressure lines, where the extra testing adds cost without adding much value.
Cost and lead time
PSL2 pipe costs more and can take longer to source, because of the extra testing, tighter chemistry and documentation. The difference is small next to the cost of a pipeline failure, but agree the PSL early so suppliers can check mill and stock availability for the right material.
Dual-certified pipe
Seamless pipe is often certified to several standards at once, for example API 5L Grade B PSL1 together with ASTM A106 Grade B and A53 Grade B. Dual certification is common and useful, but it does not turn PSL1 pipe into PSL2. If your specification requires PSL2, check that the certificate states it.
Checking PSL2 pipe on delivery
Each length of API 5L pipe is marked with the manufacturer, the specification, the size and wall thickness, the grade and the PSL. For PSL2 pipe, check that the marking and the certificate both show PSL 2 and the full grade with its suffix, and that the heat numbers on the pipe match the certificate.
- Marking shows "PSL 2" and the full grade, such as X52N
- Certificate gives the carbon equivalent and the Charpy impact results
- Yield and tensile results fall between the minimum and maximum values
- Annex H or Annex J testing is shown where your order calls for it
- Heat numbers on the pipe match the certificate
Common specification mistakes
- Asking for "X52 PSL2" without a delivery condition, which leaves the supplier to choose R, N, Q or M
- Specifying sour service without referring to Annex H, or without the client’s own sour service requirements
- Leaving out the Charpy test temperature when the project needs a lower one than the standard default
- Mixing seamless (SMLS) and welded pipe in the same line item
Need line pipe? See our line pipe and OCTG range, or send your MR for a quote.
Frequently asked questions
Can PSL2 pipe be used where PSL1 is specified?
Yes. PSL2 meets and exceeds the PSL1 requirements for the same grade, so it can be supplied in place of PSL1, usually at a higher cost.
Is X52 PSL2 the same as X52N?
X52N is one PSL2 version of X52; the N means normalized. A PSL2 order should state the full grade with its suffix, such as X52N, X52Q or X52M.
Does PSL2 mean the pipe is suitable for sour service?
Not by itself. Sour service pipe must be ordered to API 5L Annex H, which adds further chemistry, hardness and testing requirements on top of PSL2.
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