Grades · Structural & HSLA Steel · API 2H Gr.50

API 2H Gr.50

Data under review

API 2H Grade 50 is the offshore-structure plate specification: a normalized, fine-grain C-Mn steel with 345 MPa yield, −40 °C Charpy toughness and a capped carbon equivalent, written for welded jackets, decks and nodes that must survive North-Sea-class fatigue and low temperatures. Supplementary through-thickness (Z) and CTOD requirements are commonly invoked on top of the base spec.

DIN— (cf. EN 10225 S355G offshore grades)

AISIAPI 2H Gr.50

CategoryStructural & HSLA Steel

Chemical composition

Element	Content (%)
C	≤0.18
Si	0.05–0.50
Mn	1.15–1.60
P	≤0.030
S	≤0.010

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

Properties

Yield strength	≥345 MPa
Tensile strength	483–620 MPa
Impact	≥41 J at −40 °C (transverse)
Carbon equivalent	CE(IIW) ≤0.43 typical spec cap
Density	7.85 g/cm³

Heat treatment

Supplied normalized (or Q&T in thicker plate by spec edition); offshore fabrication follows AWS D1.1 / API RP 2X practice.

Equivalent grades

Standard	Designation
din	— (cf. EN 10225 S355G offshore grades)
aisi	API 2H Gr.50

Compare side by side: API 2H Gr.50 vs S355J0 · API 2H Gr.50 vs S355J2

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

Applications & Processing

Applications: Offshore jackets and topsides, jack-up rigs, marine terminals, low-temperature welded structures.

Processing: Excellent weldability by offshore standards (CE-controlled); fabrication and NDT per API RP 2X / project spec; not a general structural substitute — it is priced and certified for offshore duty.

FAQ

API 2H Gr.50 vs S355J2?: Similar strength class, different intent: 2H Gr.50 adds offshore-specific controls — CE cap, transverse −40 °C toughness and optional through-thickness quality — that commercial S355J2 does not guarantee.

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Source: API Spec 2H published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.