Same grade, different designation systems: X42 (API, yield in ksi × 1000) equals L290 (ISO/GB, yield in MPa). Certificates can normally be dual-stamped.

Grades · Pipe & Tube Steel · API 5L X42

API 5L X42

Data verified

API 5L X42 is the first of the X grades — 42 ksi minimum yield — used for moderate-pressure oil and gas pipelines. In the Chinese GB/T 9711 system the identical strength level is designated L290.

DINL290 (near)

AISIAPI 5L X42 (PSL2)

GBL290 (GB/T 9711)

CategoryPipe & Tube Steel

Chemical composition

Element	Content (%)
C	≤0.24 (PSL2)
Si	≤0.45
Mn	≤1.30 (PSL2)
P	≤0.025
S	≤0.015

Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.

Properties

Yield strength	≥290 MPa (42,000 psi)
Tensile strength	415–655 MPa (PSL2)
Density	7.85 g/cm³

Heat treatment

As-rolled, normalized or TMCP; PSL2 adds mandatory fracture-toughness testing.

Equivalent grades

Standard	Designation
din	L290 (near)
aisi	API 5L X42 (PSL2)
gb	L290 (GB/T 9711)

Compare side by side: API 5L X42 vs API 5L Grade B · API 5L X42 vs API 5L X52

Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.

Applications & Processing

Applications: Oil and gas trunk lines, water transmission, piling pipe.

Processing: Good weldability; PSL2 chemistry caps keep CE(IIW) ≤0.43 for field girth welding.

FAQ

X42 vs L290?: Same grade, different designation systems: X42 (API, yield in ksi × 1000) equals L290 (ISO/GB, yield in MPa). Certificates can normally be dual-stamped.

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Source: API 5L published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.