Grades & Standards
API Steel Grades
API steel grades are product-specific and cannot be selected by grade label alone. API 5L covers line pipe, API 5CT covers casing and tubing, API 5DP covers drill pipe, while API 2H, 2W and 2Y address distinct offshore structural steel plate categories.
This page helps pipeline engineers, drilling and completions teams and technical buyers identify the right API specification and grade group for a product and service, then hand a structured requirement to Noor Deira Steel for sourcing support.
Information date:
API scope & terminology
One standard per product family
Each API specification governs a specific product family. Grade numbers do not transfer between them — the specification, edition, PSL or group level and service condition must be named together.
API 5L
Line pipe
Gas and liquid transmission, PSL 1 or PSL 2.
API 5CT
Casing & tubing
Wellbore tubulars, by group and heat treatment.
API 5DP
Drill pipe
Rotary-drilling tubular, tied to tool joint.
API 2H / 2W / 2Y
Offshore plate
Distinct structural plate categories, separate Z-quality.
API Steel Grades Product Mapper
Identify the API specification for your requirement
Seven inputs narrow the decision to a specification family and grade group. The mapper never infers compliance or equivalence — where the signal is insufficient or conflicting, it returns 'Technical review required' instead of a guess.
What the mapper does and does not do
- Narrows to an API specification family and grade group from product and service.
- Flags which inputs are still unconfirmed before they become a quoting error.
- Does not assert API compliance, Monogram status or equivalence — those are confirmed in technical review.
Guides are indicators only. Final material selection follows the applicable project specification and current standard edition.
Mapping matrix
API specifications, by product and service
No two API grades are automatically interchangeable. Confirm product form, specification edition, dimensions, manufacturing route, service environment, inspection and documentation before ordering.
| Product category | API specification | Example grade family | Manufacturing / delivery condition | Service consideration | Required buyer inputs | Selection limitation | Next route |
|---|---|---|---|---|---|---|---|
| Line pipe | API 5L | A25, A, B, X42–X80 | PSL 1 or PSL 2; seamless or welded (ERW / LSAW); specified yield. | Gas or liquid transmission; sour service drives additional requirements. | Grade, PSL level, diameter, wall, coating, end finish and edition. | PSL 2 adds tighter chemistry, toughness and NDE — not interchangeable with PSL 1. | Steel Pipes |
| Casing & tubing | API 5CT | H40, J55, K55, N80, L80, C90, T95, P110 | Seamless or ERW; specified strength and heat treatment. | Wellbore service; corrosion and hydrogen-sulphide (sour) conditions vary by grade. | Group and grade, connection type, drift, heat treatment and edition. | Grade alone is insufficient — group (1, 2, 3, 4) and H2S service class must be stated. | Steel Pipes |
| Line pipe (coated/offshore) | API 5L | X52–X70 | Welded or seamless with marine coating and field-joint treatment. | Subsea or coastal transmission requiring corrosion and impact toughness. | Coating system, impact temperature, sour service and edition. | Offshore service frequently adds project-specific requirements above API 5L itself. | Steel Pipes |
| Drill pipe | API 5DP | E75, X95, G105, S135 | Seamless; specified yield and upset end connection. | Rotary drilling; higher strength grades trade toughness for load capacity. | Grade, tool joint, internal coating and edition. | Selection is inseparable from the tool joint and connection — not a bare pipe grade. | Steel Pipes |
| Offshore structural plate | API 2H / 2W | Grade 42, 50, 60 (2H); prescribed yield (2W) | Normalised or TMCP structural plate, Z-direction governed separately. | Fixed-platform structures; 2W covers through-thickness (Z-quality) performance. | Grade, thickness, Z-direction requirement, charpy temperature and edition. | 2W addresses lamellar tearing (Z-quality) — 2H alone does not guarantee it. | Steel Plate |
| Offshore structural plate (high strength) | API 2Y | Quenched & tempered strength grades | Quenched-and-tempered high-strength plate, fabrication-critical. | Jacket nodes, topside and high-load members where weight is a driver. | Grade, thickness, toughness, weldability and edition. | Strengthening via Q&T changes weldability — welding procedure must be confirmed. | Steel Plate |
Scope summaries are drawn from official API documentation and are for classification only — not a reproduction of the standards. See the API standards and Monogram references in the technical insight section below. Confirm the current applicable edition before ordering.
Selection checklist
The inputs that prevent a wrong API order
A complete API enquiry names the specification, edition, PSL or group, dimensions and service — not just a grade label.
- 01
Product type
Line pipe, casing, tubing, drill pipe or offshore plate — fixes the API specification.
- 02
API specification and edition
5L, 5CT, 5DP, 2H, 2W or 2Y, plus the governing year.
- 03
PSL or group level
PSL 1 / PSL 2 for line pipe; the group (1–4) for casing and tubing.
- 04
Grade and strength
The yield class (X52, N80, S135) or plate grade (Gr 50).
- 05
Manufacturing route
Seamless, ERW / LSAW, normalised / TMCP, or quenched-and-tempered.
- 06
Service environment
Sour (H2S), subsea / coated, or high-temperature service.
- 07
Dimensions and end condition
Diameter, wall / thickness, drift, connection and end finish.
- 08
Testing and inspection
Charpy, HIC / SSC, coating and NDE requirements where applicable.
- 09
Documentation
Material test certificates and the inspection paper trail required.
- 10
Quantity and destination
Volume, unit of measure and the GCC delivery destination.
Technical insight
API Grade Labels Are Not Interchangeable
Four specification families govern four different products. A grade number carries meaning only inside the specification that defines it.
| Specification | What it governs |
|---|---|
| API 5L | Line-pipe requirements, including manufacture, inspection, testing, marking and traceability. |
| API 5CT | Casing and tubing for wells, governed by group, grade and heat treatment. |
| API 5DP | Drill pipe for rotary drilling, tied to the tool joint and connection. |
| API 2H, 2W and 2Y | Distinct offshore structural plate categories — 2H intermediate strength, 2W through-thickness (Z-quality), 2Y quenched-and-tempered high strength. |
Information date: . This page is a working aid, not a reproduction of the standards, and does not assert a review or update date unless a real technical review occurred.
How Noor Deira Steel works
Concern, evidence and outcome
Capabilities tied to a verifiable step in the process, not a generic claim. API compliance, Monogram status, stock, price, certification and lead time are never stated without approved evidence.
Which API specification governs this requirement?
Every pipeline or OCTG enquiry is reconciled against the API spec and product form it names — 5L, 5CT, 5DP or the offshore plate categories — never a family-level assumption.
A brief that names the correct API specification before quotation.
Is the specification edition and PSL level confirmed?
Edition and PSL or group level are confirmed at technical review, not carried over from a past order.
No mismatch between the order and the governing edition.
Will testing and documentation match the service?
Sour-service, toughness, coating and inspection requirements are identified from the specification before release.
Material released against the tests the standard actually calls for.
Where does traceability and documentation sit?
Material certificates and inspection documentation are supplied as part of the order, without inventing API or Monogram status.
A closed-out delivery with the paper trail a QA/QC team needs.
Procurement process
From enquiry to delivery
A route-aware journey — each step maps to a real deliverable, from requirement intake through to after-sales support.
Requirement intake
Product & API scope
Technical review
Quotation
Order
Docs & quality checks
Packing
Shipping
Delivery
After-sales
FAQ
API steel grades, answered directly
What is the difference between API 5L and API 5CT?
API 5L governs line pipe used to transmit oil and gas, while API 5CT covers casing and tubing used downhole in wells. They are different product families with different grade systems, so a grade number in one does not transfer to the other.
Are API 5L grades interchangeable with each other?
No. Grades are selected by yield strength and application, and PSL 1 versus PSL 2 changes chemistry, toughness and inspection requirements. Substitution must be confirmed against the governing specification and service condition.
What do PSL 1 and PSL 2 mean for line pipe?
Product specification levels. PSL 2 imposes tighter chemical composition, toughness, non-destructive examination and traceability requirements than PSL 1. The required PSL is a buyer input, not an automatic default.
Which API specification covers offshore structural plate?
API 2H covers intermediate-strength structural plate, API 2W covers through-thickness (Z-quality) performance against lamellar tearing, and API 2Y covers quenched-and-tempered high-strength plate. They are distinct categories serving different structural duties.
Does API 5DP apply to surface line pipe?
No. API 5DP applies specifically to drill pipe used in rotary drilling. Surface transmission line is governed by API 5L, and casing or tubing by API 5CT.
How do I confirm the correct edition and documentation?
Quote the full designation including the specification year, and state the PSL or group level, connection, dimensions and any sour-service or coating requirement. Edition and documentation are confirmed at technical review before release.
Related standards
Continue across the standards directory
Move from API grades toward the equivalent material system and the other reference directories.
ASTM Steel Grades
The American standard system read against API product scope.
ViewEN Steel Grades
The European designation system and its equivalents.
ViewCarbon Steel Grades
Carbon grades organised by chemistry and strength.
ViewStainless Steel Grades
Corrosion and temperature grades.
ViewSteel Specifications
How grades map to a full specification.
ViewRequest a Quote for an API Grade
Name the API specification and grade, product form, PSL or group level, dimensions, service environment and destination. Our commercial and technical teams reconcile the requirement against the current edition.
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