Introduction to L245 Steel Pipe

L245 steel pipe is a common grade of pipeline steel specified in the ISO 3183 standard (and equivalent standards like API 5L and GB/T 9711). The "L" stands for "Line Pipe," and the "245" indicates its minimum specified yield strength of 245 Megapascals (MPa).

It is a carbon-manganese steel widely used for conveying fluids, such as oil, natural gas, and water, in pipeline transmission systems. It is considered a general-purpose, low-to-medium strength grade.

Key Equivalent Grades

L245 is equivalent to several common grades from other standards, which is crucial for international projects:

API 5L Grade B: This is the most common equivalent, especially for PSL 1 (Product Specification Level 1).

GB/T 9711 PSL1: L245 (Identical)

ASTM A53 Grade B: While similar in strength, A53 is for general structural and mechanical use, not specifically for pipelines. Chemical composition may differ slightly.

DIN 17100 St 37.2: A German structural steel grade.

Product Parameters and Technical Data

The parameters are primarily defined by two product specification levels: PSL 1 and PSL 2. PSL 2 has more stringent requirements for chemical composition, mechanical properties, toughness, and testing.

1. Chemical Composition (Mass Fraction, %)

The table below shows the maximum percentages unless a range is indicated.

Element	API 5L / ISO 3183 PSL 1 Requirement	Typical API 5L / ISO 3183 PSL 2 Requirement
Carbon (C)	≤ 0.22	≤ 0.20 (Max. CE is more critical for PSL 2)
Manganese (Mn)	≤ 1.20	≤ 1.20
Phosphorus (P)	≤ 0.025	≤ 0.025
Sulfur (S)	≤ 0.015	≤ 0.015
Silicon (Si)	-	≤ 0.45
Carbon Equivalent (CE)	-	CE (Pcm) ≤ 0.23 or CE (IIW) ≤ 0.43

Note on PSL 2: For PSL 2, controlling the Carbon Equivalent (CE) is mandatory to ensure good weldability. The specific formula (Pcm or IIW) is agreed upon between the manufacturer and the purchaser.

2. Mechanical Properties

Property	API 5L / ISO 3183 PSL 1 Requirement	API 5L / ISO 3183 PSL 2 Requirement
Yield Strength (Min.), Rₜ₀.₅	245 MPa (35,500 psi)	245 MPa (35,500 psi)
Tensile Strength, Rₘ	415 MPa to 760 MPa (60,200 psi to 110,200 psi)	415 MPa to 760 MPa (60,200 psi to 110,200 psi)
Elongation (Min.)	Refer to standard table based on sample size.	Refer to standard table based on sample size.
Charpy V-Notch Impact Test	Not Required	Required. Test temperature and minimum absorbed energy are specified by the purchaser.

3. Dimensional Tolerances (Common for Seamless and Welded Pipes)

Dimension	Standard Tolerance (Examples)
Outside Diameter (D)	± 0.75% of D for D < 508mm; ± 0.50% of D for D ≥ 508mm
Wall Thickness (t)	+ / - 12.5% of t
Length	+ / - 100 mm for random lengths; + / - 6 mm for exact lengths
Straightness	≤ 0.0015 x length (e.g., 1.5mm per meter of length)

Product Tables Summary

Table 1: Common Sizes and Weights (PSL 1 & PSL 2)

(Note: Weight is theoretical. Wall thicknesses are common examples.)

Nominal Size (NPS)	Outside Diameter (OD)	Wall Thickness (WT)	Schedule / Type	Weight (Approx. kg/m)
2 inch	60.3 mm	3.91 mm	SCH 40	5.44
4 inch	114.3 mm	6.02 mm	SCH 40	16.07
8 inch	219.1 mm	8.18 mm	SCH 40	42.55
12 inch	323.9 mm	9.53 mm	SCH 30	73.86
18 inch	457 mm	9.53 mm	SCH 20	105.1
24 inch	610 mm	12.70 mm	SCH 20	187.2

Table 2: Comparison of PSL 1 vs. PSL 2

Feature	PSL 1	PSL 2
Primary Application	General purpose, low-pressure fluid conveyance.	Critical service, higher-pressure transmission (e.g., main oil/gas lines).
Chemical Control	Basic control of C, Mn, P, S.	Stricter control, including Carbon Equivalent (CE) for weldability.
Impact Testing	Not required.	Mandatory. Ensures toughness at low temperatures.
Testing & Inspection	Standard mechanical tests, hydrostatic test.	More extensive non-destructive testing (NDT) like ultrasonic inspection.

Common Manufacturing Processes

Seamless (SMLS): Designated as L245 N. Made by piercing a solid billet. No seam weld, ideal for high-pressure applications.

Welded (EW / ERW / SAW):

Electric Welded (L245 W): Formed from plate/skelp and welded using electric resistance (ERW) or electric fusion (EFW).

Longitudinally Submerged Arc Welded (L245 S): Designated as L245 M. A plate is formed and welded longitudinally using the SAW process, common for large diameters.