PSL 1 vs PSL 2 — Full Comparison
Basic limits on C, Mn, P, S. No carbon equivalent (CE) requirement.
Tighter limits on C, Mn, P, S. Mandatory CE maximum by grade and wall thickness.
−12.5% undertolerance. A 0.500" wall may be as thin as 0.4375".
−8% undertolerance. A 0.500" wall may be as thin as 0.460".
No Y/T ratio requirement.
Y/T ratio ≤ 0.93 for X grades. Ensures adequate work hardening before tensile failure.
No Charpy testing required in base specification.
Mandatory CVN testing. Temperature and minimum energy values are grade and wall dependent.
Basic seam inspection. Hydrostatic test or electromagnetic inspection.
Full-length UT or RT on weld seam. More stringent acceptance criteria.
Not required on pipe body in base spec.
Full-body UT inspection required for grades X60 and above.
±1.0% of specified OD.
±0.75% of specified OD. Tighter fit-up for field welding.
Standard hold time and pressure per table.
Higher test pressure requirements. Longer hold time in some cases.
Marked with grade only (e.g., "X52").
Marked with grade and "PSL2" (e.g., "X52 PSL2"). Traceable to PSL 2 requirements.
SR15 (HIC) and SR16 (SSC) cannot be invoked on PSL 1 pipe.
SR15 and SR16 require PSL 2 as a base. PSL 2 is the gateway to sour service qualification.
Bottom line: PSL 2 is not a premium upsell — it is the baseline expectation for any serious transmission project. The wall thickness tolerance difference alone (−0.875" vs −8%) changes pressure design calculations. Most major operators and engineering contractors specify PSL 2 as the default for all line pipe procurement.