What is the difference between PSL1 and PSL2 in API 5L?

PSL1 is the standard product specification level for most onshore applications. PSL2 adds mandatory Charpy impact testing, tighter chemistry limits, maximum yield strength limits, and additional non-destructive inspection requirements.

When is PSL2 mandatory?

PSL2 is required for sour service environments (HIC and SSC per NACE MR0175 / ISO 15156), offshore pipelines, low-temperature service below 0°C, and grades X80 (L555) and above. Many operator standards also mandate PSL2 for gas transmission systems.

Are X80 and above available at PSL1?

No. API 5L only defines grades X80 (L555) and above at PSL2. X70 (L485) and lower grades exist at both PSL1 and PSL2.

Does PSL2 significantly increase pipe cost?

Yes, typically 5–15% above PSL1 pricing due to additional testing, inspection, and chemistry control. The selector helps engineers justify the upgrade against specific technical service requirements.

API 5L PSL1 vs PSL2 Selector

PSL1 (Product Specification Level 1) is the standard quality level. PSL2 adds mandatory Charpy impact testing, max yield strength limits, lower carbon equivalent, and tighter NDE. This tool guides you through the key service conditions to determine which PSL level applies to your project.

Based on API Spec 5L 46th edition · for reference only — verify against your project specification.

Step 1 — Select grade

Grades L555/X80 and above exist in PSL2 only — PSL1 versions are not defined in the standard.

Step 2 — Service conditions

Check all that apply to your project.

Sour service (H₂S present)

Pipeline carries gas or liquid containing H₂S. Typically governed by NACE MR0175 / ISO 15156. PSL2 chemistry controls (lower S, P, CE) are required by most project specs for sour-service line pipe.

Offshore or subsea pipeline

Pipeline installed offshore or routed under water. DNV-ST-F101 and most major offshore codes mandate PSL2 as minimum for subsea linepipe.

Low-temperature service (<−20 °C / −4 °F)

Charpy impact testing at low temperature is only mandated under PSL2. PSL1 has no toughness requirement.

High-consequence area (ASME B31.8 Class 3/4 or EN 1594)

Pipelines near populated areas or critical infrastructure. Project specifications for Class 3 and 4 locations commonly require PSL2.

Owner/operator specification requires PSL2

Major operators (Saudi Aramco, Shell, ExxonMobil, BP, etc.) and NOCs typically specify PSL2 as their minimum for mainline and gathering pipe regardless of other conditions.

PSL2 delivery conditions & grade naming

Under PSL2, the delivery condition (heat treatment route) must be specified. The suffix is appended to both the L-designation and the X-designation:

Suffix	Delivery condition	Example (L415 / X60)	Typical product
R	As-rolled (PSL2 only, low grades)	L290R / X42R	Low grades only (≤ L290/X42)
N	Normalized or normalized-formed / normalized-rolled (PSL2)	L415N / X60N	Seamless; lower-strength welded
Q	Quenched and tempered (PSL2)	L415Q / X60Q	Higher-strength seamless; HPHT service
M	Thermomechanically rolled or thermomechanically formed (PSL2, welded pipe)	L415M / X60M	SAW / LSAW / SSAW large-diameter welded

Source: API 5L 46th edition, Annex H and Table 1.

PSL1 vs PSL2 — key differences

Requirement	PSL1	PSL2
Charpy CVN toughness	Not required	Mandatory at specified test temp
Max yield strength	No upper limit	Upper SMYS limit specified
Yield / tensile ratio	No limit	≤ 0.93 (large OD, D > 323.9 mm)
Carbon equivalent (CE IIW)	Not specified	Max 0.43 (most grades)
Sulphur content	≤ 0.030%	≤ 0.015%
Phosphorus content	≤ 0.030%	≤ 0.025%
Delivery condition	Not specified	Must be stated (R/N/Q/M)
NDE (non-destructive testing)	Basic	Enhanced — additional UT/MT/ET
Hydrostatic test	Standard (60% SMYS)	Higher options available (up to 90%)

Related tools & articles

API 5L Spec Tables → Pipeline Design Calculator → AI Pipe Grade Selector →

Disclaimer: This tool provides guidance only. PSL level selection must be confirmed against your project specification, applicable design code (ASME B31.8, DNV-ST-F101, EN 1594, etc.), and the current edition of API 5L. Always consult a qualified pipeline engineer before finalising material specifications.