API 5L X42 Pipe

What does X42 mean?

API 5L X42 pipe is a medium-strength carbon steel line pipe grade specified by the American Petroleum Institute (API) Specification 5L for oil and gas pipeline transportation.

The grade X42 indicates a minimum yield strength of 42,100 psi (290 MPa), while its ISO 3183 equivalent designation is L290. Compared with API 5L Grade B pipe, API 5L X42 provides higher yield strength and improved mechanical performance, making it suitable for pipelines that require better pressure resistance and durability.

API 5L X42 pipes are widely used for transporting oil, natural gas, water, and other fluids in onshore and offshore pipeline systems. They are available in different manufacturing types, including seamless pipe, ERW pipe, HFW pipe, LSAW pipe, and SSAW pipe, depending on diameter, pressure requirements, and project specifications.

As one of the commonly used API 5L line pipe grades, X42 provides a balance between strength, weldability, and cost efficiency, making it a popular choice for medium-pressure transmission pipelines.

API 5L X42 Pipe Specification

API 5L X42 pipe is manufactured according to:
Standard: API Specification 5L – Line Pipe
Equivalent Grade: ISO 3183 L290
Steel Type: Carbon Steel Line Pipe
Product Specification Level: PSL1 / PSL2
Applications: Onshore pipelines, offshore pipelines, oil and gas transmission systems
The basic specifications are shown below:

Item	API 5L X42 Pipe Specification
API Grade	X42
ISO Equivalent	L290
Minimum Yield Strength	290 MPa (42,100 psi)
Minimum Tensile Strength	414 MPa (60,200 psi)
Product Level	PSL1, PSL2
Pipe Type	Seamless, ERW, HFW, LSAW, SSAW
Size Range	1/2" to 60" OD
Standard Length	Single Random, Double Random, 12 m or customized
End Type	Plain End, Beveled End, Threaded End
Coating Options	FBE, 3LPE, 3LPP, Epoxy Coating

API 5L X42 is positioned between Grade B and higher-strength grades such as X52 and X60. It provides higher load-bearing capacity than Grade B while maintaining good weldability and fabrication performance.
For pipeline projects requiring moderate strength improvement without selecting higher-cost high-strength steel grades, API 5L X42 is often an economical solution.

API 5L X42 Pipe PSL1 and PSL2 Specification

API 5L X42 pipes are available in two product specification levels:
PSL1 (Product Specification Level 1)
PSL2 (Product Specification Level 2)
The main difference between PSL1 and PSL2 is the level of chemical control, mechanical testing, and quality requirements.
API 5L X42 PSL1 Pipe
API 5L X42 PSL1 is the standard quality level used for general pipeline applications.

API 5L X42 PSL2 Pipe
API 5L X42 PSL2 has stricter requirements for production control and inspection.
Compared with PSL1, PSL2 requires:
Lower sulfur and phosphorus limits
More strict chemical composition control
Mandatory impact testing for applicable grades
Improved traceability
Additional non-destructive testing requirements
API 5L X42 PSL2 is commonly selected for critical pipeline systems where higher reliability and safety are required.
Typical delivery conditions include:

Designation	Delivery Condition
X42N	Normalized / Normalizing Rolled
X42M	Thermomechanical Rolled
X42Q	Quenched and Tempered

API 5L X42 Sour Service Pipe

For pipelines transporting sour gas containing hydrogen sulfide (H₂S), API 5L X42 can also be supplied in sour service grades:
X42NS
X42MS
X42QS
These grades require additional control of:
Hydrogen induced cracking (HIC)
Sulfide stress cracking (SSC)
Chemical composition
Impact toughness

Sour service API 5L X42 pipes are commonly used in oil and gas fields with corrosive operating environments.

API 5L X42 Chemical Composition

The chemical composition of API 5L X42 pipe is carefully controlled to achieve an optimal balance between strength, weldability, and corrosion resistance. Compared with higher-strength grades, X42 maintains a relatively low carbon content, making it easier to weld while still providing sufficient mechanical performance for most pipeline systems.
PSL2 pipes have stricter limits on phosphorus and sulfur than PSL1, resulting in improved toughness and higher quality consistency for critical pipeline applications.

API 5L X42 Chemical Composition (Maximum %)

PSL	Grade	C	Mn	P	S	Ti
PSL1	X42	0.28	1.3	0.03	0.03	0.04
PSL2	X42	0.24	1.3	0.025	0.015	0.04

API 5L X42 Mechanical Properties

API 5L X42 pipe offers higher yield strength than API 5L Grade B while maintaining similar tensile strength. This makes it an economical choice for medium-pressure transmission pipelines where additional strength is required without significantly increasing material costs.
API 5L X42 Mechanical Properties

PSL	Grade	Yield Strength (Min)	Tensile Strength (Min)	Elongation*
PSL1	X42	290 MPa (42,100 psi)	414 MPa (60,200 psi)	According to API 5L
PSL2	X42	290 MPa (42,100 psi)	414 MPa (60,200 psi)	According to API 5L

API 5L X42 vs Grade B vs X52

When selecting line pipe materials, engineers often compare API 5L X42 with Grade B and X52. Although all three grades are widely used in pipeline construction, their mechanical properties and recommended applications differ.

Property	Grade B	X42	X52
Minimum Yield Strength	241 MPa	290 MPa	359 MPa
Minimum Tensile Strength	414 MPa	414 MPa	455 MPa
ISO Equivalent	L245	L290	L360
Typical Application	Low-pressure pipelines	Medium-pressure pipelines	High-pressure transmission pipelines
Cost	Lower	Moderate	Higher

Which Grade Should You Choose?
Grade B is suitable for standard water and gas transportation projects with relatively low pressure requirements.
API 5L X42 offers improved strength and durability while remaining cost-effective, making it one of the most widely specified grades for oil and gas transmission.
API 5L X52 is recommended for higher-pressure pipelines or projects requiring greater structural performance.

API 5L X42 Seamless Steel Pipe

API 5L X42 seamless steel pipe is manufactured from solid steel billets without a welded seam, providing excellent pressure resistance, structural integrity, and reliability. It is widely used in oil and gas transmission, petrochemical plants, power generation, and other high-pressure pipeline systems.
Manufactured in accordance with API 5L and ISO 3183 (L290), seamless X42 pipe is typically supplied in normalized, normalized rolled, or thermomechanically processed conditions, depending on project requirements.

Item	Specification
Standard	API 5L / ISO 3183
Grade	X42 (L290)
Yield Strength	≥290 MPa
Tensile Strength	≥414 MPa
Manufacturing Process	Hot Rolled or Cold Drawn Seamless
Typical Size	Up to 24 in. OD

API 5L X42 Pipe Coating Options

Pipeline coating plays an important role in protecting API 5L X42 pipes from:
External corrosion
Soil erosion
Chemical attack
Marine environment
The suitable coating system depends on pipeline location, operating temperature, transportation medium, and service life requirements.

Coating Type	Full Name	Main Advantages	Typical Applications
FBE	Fusion Bonded Epoxy	Excellent corrosion resistance	Underground pipelines
3LPE	Three Layer Polyethylene	High mechanical protection	Oil & gas transmission
3LPP	Three Layer Polypropylene	High temperature resistance	Offshore pipelines
Coal Tar	Coal Tar Epoxy Coating	Good chemical resistance	Industrial pipelines
Black Painting	Black Epoxy / Paint Coating	Basic protection	General applications
Varnish	Anti-corrosion varnish coating	Temporary protection	Storage and transportation

API 5L X42 Pipe Weight Chart

Pipe weight is calculated based on:
Outside diameter
Wall thickness
Steel density
Approximate formula:

Weight(kg/m)=0.02466×(OD−WT)×WT

Where:
OD = Outside Diameter (mm)
WT = Wall Thickness (mm)

Size	OD	WT	Weight
6"	168.3 mm	8 mm	32.0 kg/m
8"	219.1 mm	10 mm	51.7 kg/m
10"	273.1 mm	12 mm	77.0 kg/m
12"	323.9 mm	12 mm	92.0 kg/m
16"	406.4 mm	14 mm	135 kg/m

API 5L X42 Pipe Typical Manufacturing Route

Process	OD Range	WT Range	Note
Seamless (mandrel mill / plug)	½″ – 24″	2 – 40 mm	Preferred for small OD, high pressure
ERW / HFW	½″ – 24″	2 – 16 mm	High-speed, economical
JCOE LSAW	16″ – 56″	6 – 50 mm	Most common for X42 PSL 2
UOE LSAW	20″ – 48″	6 – 40 mm	Mechanical expansion for roundness
Rolled plate (double seam)	40″ – 80″	25 – 80 mm	Heavy-wall, custom

All welded pipes require hydrostatic test (per API 5L holding pressure), plus UT/RT on the seam. PSL 2 adds full-body UT, hardness survey, and CVN impact.

FAQ

1. What is API 5L X42 pipe?
API 5L X42 pipe is a carbon steel line pipe grade with a minimum yield strength of 42 ksi (290 MPa), mainly used for oil and gas transportation pipelines.
2. What is the difference between API 5L X42 PSL1 and PSL2?
PSL2 has stricter requirements for chemical composition, mechanical testing, impact toughness, and quality control compared with PSL1.
3. Is API 5L X42 available as seamless pipe?
Yes. API 5L X42 can be manufactured as seamless pipe as well as ERW, SSAW, and LSAW welded pipe.
4. What is the difference between API 5L X42 and Grade B?
X42 has higher yield strength than Grade B, providing better pressure resistance for pipeline applications.
5. Is API 5L X42 suitable for offshore pipelines?
Yes, especially API 5L X42 PSL2 with appropriate coating and impact testing requirements.