NORSOK N-004 vs DNV-OS-C101: Structural Design Standards for Offshore Engineers

1. The regulatory hierarchy

The most common question offshore structural engineers face on NCS projects is not which standard is technically superior — it is which standard is legally mandatory. The answer flows from the regulatory authority that has jurisdiction over the asset.

PSA Norway (Petroleum Safety Authority) is the Norwegian regulator for petroleum activities on the NCS. PSA regulations — in particular the Management Regulations and the Facility Regulations — require compliance with relevant NORSOK standards as part of their framework regulations. For structural design of NCS fixed installations, that means NORSOK N-004 is the governing standard by regulatory mandate.

DNV (Det Norske Veritas) is a classification society. When an asset is built to DNV class — meaning DNV issues the class certificate — the owner and designer must comply with DNV's class rules and offshore standards, including DNV-OS-C101 for structural steel design. DNV class is mandatory for mobile offshore units (MOUs) operating under flag-state requirements, and is commonly used for FPSOs, semi-submersibles, jackups, and drillships.

The key distinction NORSOK N-004 is a PSA regulatory requirement — it applies because Norwegian law says so. DNV-OS-C101 is a class requirement — it applies because the asset seeks or holds DNV class. On a typical NCS project you will encounter both: the host facility governed by N-004, and an attached or temporally-operated DNV-classed unit governed by DNV-OS-C101.

Understanding this hierarchy matters for every project. When a conflict exists between the two standards, the regulator (PSA) takes precedence for NCS assets. Where DNV class is also required, both sets of requirements must be met — the more conservative provision governs at each design check.

When you have both on one project

A typical scenario: an NCS fixed platform (N-004 governs) receives a DNV-classed crane barge or a DNV-classed floating accommodation unit alongside. The fixed installation structure is designed to N-004. The mooring and hull of the floating unit are designed to DNV-OS-C101. The crane pedestal and interface steelwork may be subject to both. This split must be resolved explicitly in the project's Basis of Design (BoD) before detailed engineering begins.

2. NORSOK N-004 scope and applicability

NORSOK N-004 (Design of Steel Structures) is the primary structural design standard for offshore steel structures on the Norwegian Continental Shelf. The current revision is Rev 3, October 2013. It is published by Standards Norway and freely available from their website.

N-004 covers:

All limit states: Ultimate (ULS), Accidental (ALS), Fatigue (FLS), and Serviceability (SLS)
Structural members in tension, compression, bending, shear, and combined loading
Tubular members and tubular joints (K, T, Y, X joint types)
Grouted connections (Annex A) — critical for jacket refurbishments and pile-to-sleeve connections
Connections: bolted and welded joints, including fillet and full-penetration welds
Plated structures: plates, stiffened panels, girders
Aluminium structures (Section 12)

Eurocode 3 baseline N-004 is based on Eurocode 3 (EN 1993) but with NCS-specific modifications. Where N-004 is silent on a topic, Eurocode 3 applies as the background document. This is important: N-004 does not reinvent structural mechanics — it adapts the Eurocode framework to the NCS environment, load conditions, and regulatory context.

N-004 is referenced by several other NORSOK standards:

NORSOK N-001 (Integrity of offshore structures) — the overarching structural integrity standard that mandates use of N-004
NORSOK N-003 (Actions and action effects) — the load standard used with N-004
NORSOK Z-013 (Risk and emergency preparedness analysis) — requires ALS checks in accordance with N-004
NORSOK M-001 (Material selection) — referenced for material grades used in N-004-governed structures

The standard applies to fixed installations (jackets, jack-up platforms in fixed mode, topsides primary structure) and to temporary structures on NCS facilities. It does not cover subsea pressure-containing equipment (covered by NORSOK U-001/U-009) or pipeline structural design (DNVGL-ST-F101).

3. DNV-OS-C101 scope and applicability

DNV-OS-C101 (Design of Offshore Steel Structures, General — LRFD Method) is DNV's general structural standard for offshore steel structures. It is part of DNV's Offshore Standards series and is maintained as part of DNV's rolling rule revision cycle — check the DNV Rules portal for the current edition.

DNV-OS-C101 is a general standard that applies across many asset types:

Floating offshore units — semi-submersibles, FPSOs, jackups under DNV class
Fixed offshore platforms under DNV class
Ship-shaped offshore units
Topside modules and equipment skids on DNV-classed vessels
Offshore wind support structures (when referenced by the relevant DNV wind standard)

LRFD method DNV-OS-C101 uses the Load and Resistance Factor Design (LRFD) method throughout. This is consistent with NORSOK N-004's approach — both use partial safety factors applied to characteristic loads and characteristic resistances. Engineers transitioning between the two standards will recognise the same philosophical framework, even though the specific factors differ.

DNV-OS-C101 works in conjunction with other DNV standards:

DNV-OS-C102 — structural design of floating production, storage and offloading (FPSO) units
DNV-OS-E301 — position mooring and related environmental loads
DNV-OS-B101 — metallic materials (equivalent role to NORSOK M-001)
DNVGL-RP-C203 — fatigue design of offshore steel structures (shared reference with N-004)
DNVGL-RP-C205 — environmental conditions and environmental loads

Unlike N-004, which is primarily a fixed-structure standard, DNV-OS-C101 is written to accommodate the full breadth of offshore asset types. Its load provisions and structural checks are calibrated for a global fleet context rather than specifically for NCS conditions.

4. Key technical differences

Despite covering the same engineering problem — structural design of offshore steel — N-004 and DNV-OS-C101 differ in several technically important ways. Engineers working across both must understand these differences to avoid under-design or unnecessary conservatism.

Topic	NORSOK N-004	DNV-OS-C101
Basis	Eurocode 3 with NCS modifications	DNV class rule framework, LRFD
Regulatory status	PSA mandatory for NCS fixed installations	Class mandatory for DNV-classed assets
Load standard	NORSOK N-003	DNV-OS-E301, DNVGL-RP-C205
ULS load factors	γ_G = 1.3 (permanent), γ_Q = 1.5 (variable) — per N-003	γ_f = 1.3 / 1.5 — similar LRFD factors, but calibrated to DNV rule set
ALS design	N-004 Section 7 — NCS-specific collision/blast energies per NORSOK Z-013	DNV-OS-C101 Section 7 — calibrated to class rules and vessel-specific scenarios
Fatigue reference	DNVGL-RP-C203 (referenced in N-004 Annex C)	DNVGL-RP-C203 (referenced in DNV-OS-C101 Section 5)
Tubular joints	N-004 Section 6 — Efthymiou SCFs, gap/overlap	DNV-OS-C101 Chapter 6 — same Efthymiou equations
Grouted connections	N-004 Annex A — detailed grout design rules	Referenced to DNV-OS-C106 or specific class notes
Material standard	NORSOK M-001 + NORSOK M-120	DNV-OS-B101
Maintenance cycle	Periodic revision by Standards Norway (Rev 3 since 2013)	Rolling revision by DNV — check current edition before use

Load factor alignment

For most routine structural members, the ULS load factors in N-004/N-003 and DNV-OS-C101 produce similar design loads. The more significant differences emerge in:

Environmental load factors: N-003 and DNV-RP-C205 use different return period conventions and partial factors for wave, wind, and current — verify alignment when combining loads from different sources
ALS energy levels: N-004 ALS collision energy is specified by PSA/NORSOK Z-013 for NCS conditions; DNV-OS-C101 ALS energy depends on the vessel classification and route
Temporary phases: N-004 Annex B addresses temporary conditions (installation, float-over, hook-up) with specific γ factors for short-duration loadings

5. Tubular joint design

Tubular joints are a critical detail in offshore jacket design, and both N-004 and DNV-OS-C101 dedicate substantial sections to them. In practice, the methodologies are closely aligned — both trace their lineage to the same research base — but there are clause-level differences that matter during detailed design.

Joint types and geometry

Both standards classify tubular joints by their geometric configuration:

K-joints: braces on opposite sides of the chord, loads predominantly balanced in the chord — most common in jacket brace-chord intersections
T- and Y-joints: single brace connecting to chord, unbalanced load — common at chord ends and joint cans
X-joints: two braces on opposite sides with load passing through chord — requires chord utilization check
KT-joints: three braces in a plane — requires classification into K and T components

The governing equations for chord face plasticity (ULS) are essentially the same in both standards, derived from the research by Yura, Zettlemoyer, and the CIDECT database. Engineers familiar with one standard will not find surprises in the joint strength equations of the other.

Stress concentration factors (SCFs)

Both N-004 and DNV-OS-C101 reference the Efthymiou equations for computing stress concentration factors at tubular joints. These SCFs are applied in fatigue design per DNVGL-RP-C203. The Efthymiou equations cover:

Brace and chord SCFs at the saddle and crown positions
Validity ranges for the geometric parameters (β, γ, τ, θ, ζ)
Out-of-plane bending corrections


SCF = f(β, γ, τ, θ, ζ)
β = d_brace / D_chord  (diameter ratio)
γ = D_chord / (2T_chord)  (chord slenderness)
τ = t_brace / T_chord  (wall thickness ratio)
θ = brace-to-chord angle
ζ = gap parameter (K-joints)

Validity range compliance The Efthymiou equations have stated geometric validity ranges. When joint geometry falls outside these ranges — common in very large-diameter chord cans or very small brace angles — SCFs must be determined by finite element analysis or physical testing. Both N-004 and DNV-OS-C101 permit FE-derived SCFs with appropriate justification. Do not extrapolate Efthymiou equations outside their validity domain.

Chord utilization ratio

The chord utilization ratio (Qu × Qf check) appears in both standards. The Qf term reduces joint capacity when the chord cross-section is highly stressed by axial or bending loads. A heavily utilized chord can significantly reduce brace capacity — this interaction must be checked at every joint. N-004 §6.4 and DNV-OS-C101 Chapter 6 handle this consistently.

Grouted joints — N-004 Annex A

One area where N-004 goes significantly further than DNV-OS-C101 is grouted connections. N-004 Annex A provides a comprehensive design method for grouted pile-to-sleeve connections, including:

Axial capacity calculation based on bond stress and shear keys
Requirements for grout mix and compressive strength (typically 60–80 MPa cube strength)
Shear key geometry requirements (height, spacing, width-to-height ratio)
Bending and torsion capacity of grouted connections
Fatigue of grouted connections under cyclic loading

This is particularly relevant for jacket refurbishments where grouted reinforcements are added to existing pile sleeves. DNV-OS-C101 points to DNV-OS-C106 and specific class notes for equivalent guidance. On NCS jacket work, N-004 Annex A governs.

6. Accidental limit state (ALS)

The Accidental Limit State (ALS) is where regulatory philosophy most clearly separates N-004 from DNV-OS-C101. The purpose of ALS design is to ensure the structure does not suffer disproportionate collapse under defined accidental events — the structure may sustain local damage but must maintain global integrity.

N-004 ALS — NCS regulatory context

On NCS installations, the ALS design is driven by PSA requirements and the output of NORSOK Z-013 risk analyses. The key accidental events defined in N-004 §7 are:

Ship collision: Supply vessel or shuttle tanker collision energy specified per NORSOK Z-013 — typically 14 MJ (broadside) to 11 MJ (bow/stern) for supply vessel collision on NCS facilities, depending on traffic analysis
Dropped objects: Defined by crane operations risk analysis — typical design loads 2–10 tonnes at height of 20–30 m, giving impact energies of 0.4–3 MJ depending on dropped mass and height
Explosion and fire: Blast overpressure from NORSOK Z-013 risk analysis — structural blast walls designed for defined overpressure vs. duration impulse
Extreme wave / abnormal wave event

PSA ALS governs on NCS Even if a structure on the NCS also holds DNV class, the PSA's ALS energy levels from NORSOK Z-013 govern. DNV class requirements are not a substitute for PSA regulatory ALS compliance. The PSA ALS loads must be documented and demonstrated — this cannot be waived by reference to class approval.

DNV-OS-C101 ALS — class context

DNV-OS-C101 ALS is calibrated to vessel and MOU context. Key events covered include:

Vessel collision between the floating unit and attendant vessels — energy levels per vessel mass and speed defined in DNV class rules
Flooding of compartments — progressive flooding ALS analysis for floating stability
Fire and explosion — per DNV fire safety class
Mooring line failure — residual capacity with one or more lines failed

For a DNV-classed FPSO operating on the NCS, the ALS design must satisfy both the PSA/NORSOK Z-013 scenario (for the topsides and mooring interface) and the DNV ALS rules for the hull. The project's risk analysis must reconcile these requirements and document the governing design case at each location.

ALS analysis method

Both standards permit the same range of ALS analysis methods:

Elastic perfectly plastic (EPP) analysis — simplified, conservative
Nonlinear static pushover analysis — commonly used for ship collision and dropped object
Nonlinear dynamic analysis — required for blast/explosion and extreme wave events
Ductility analysis with energy methods — energy absorption via plastic deformation, per N-004 Annex A or DNV-OS-C101 Appendix C

7. Fatigue design

Fatigue is the life-limiting failure mode for most offshore structural connections. Both NORSOK N-004 and DNV-OS-C101 align on the same fatigue methodology, which simplifies practice considerably.

Shared reference: DNVGL-RP-C203

DNVGL-RP-C203 (Fatigue Design of Offshore Steel Structures) is referenced by both N-004 Annex C and DNV-OS-C101 Section 5. This means the S-N curves, the hot spot stress method, the notch stress method, and the fracture mechanics approach are effectively the same regardless of which primary structural standard governs.

RP-C203 provides:

S-N curves for seawater with and without cathodic protection (curves B through W, and tubular joint curves T and TJ)
Hot spot stress extrapolation methodology for plate and tubular connections
Notch stress methodology for detailed weld toe assessment
SCF tables and equations for standard weld geometries
Fracture mechanics approach for inspection planning (crack growth calculations)

In practice: use RP-C203, let the load standard differ The fatigue calculation procedure — cycle counting, damage accumulation via Palmgren-Miner, S-N curve selection — is identical whether you are working to N-004 or DNV-OS-C101. The difference lies in the environmental load input: use NORSOK N-003 scatter diagrams for NCS sites, or DNV-RP-C205 for non-NCS global locations. The structural fatigue capacity calculation is the same.

Fatigue design life and DFF

Both standards require a design fatigue factor (DFF) applied to the target design life to account for inspection accessibility and consequence of failure:

Location / accessibility	N-004 DFF	DNV-OS-C101 DFF
Above water, accessible for inspection and repair	1.0	1.0
In the splash zone, limited inspection access	2.0	2.0
Below water, inspectable by diver or ROV	2.0	2.0
Below water, not accessible for inspection	10.0	10.0

The DFF values shown above are consistent across both standards. For an NCS fixed installation with a 25-year design life, an inaccessible joint below the mudline must demonstrate fatigue life ≥ 250 years. On DNV-classed floating units, the same logic applies to hull structural details below the waterline that cannot be inspected in service.

Weld improvement techniques

Where fatigue life is insufficient, both standards permit weld improvement techniques documented in RP-C203: hammer peening, ultrasonic impact treatment (UIT), and profile grinding. The improvement factors are the same regardless of whether N-004 or DNV-OS-C101 governs. Any improvement must be verified by the manufacturer and agreed with the certifying authority (PSA verifier or DNV surveyor).

8. Dual-standard projects

Dual-standard projects — where both N-004 and DNV-OS-C101 apply to different systems on the same installation — are routine on the NCS. The most common scenarios:

NCS FPSO: The hull structure is designed to DNV-OS-C101 (DNV class requirement). The topsides process structure, primary deck beams, and equipment supports are designed to NORSOK N-004 (PSA requirement). The interface — typically the hull-topsides integration (HTI) connection — must be checked against both standards. The more conservative provision governs.

Jacket with DNV-classed crane: The jacket structure is governed by N-004. The crane itself is DNV-classed and its pedestal, slew ring foundation, and local reinforcements are subject to DNV-OS-C101 and the relevant DNV crane standard. The crane pedestal connection to the jacket deck must satisfy the jacket's N-004 load path and the crane's DNV-OS-C101 local requirements simultaneously.

Temporary modular structure on NCS: A temporary bridge or module support frame installed on an NCS asset. Per NORSOK Z-015 (temporary equipment), N-004 can apply if the temporary structure is classified as a structural system of the host facility. If the temporary structure has its own DNV class, DNV-OS-C101 also applies. Clarify scope at project kickoff.

Semi-submersible on NCS: The pontoons, columns, and bracing — all part of the hull class — are governed by DNV-OS-C101. Any permanently installed topsides structure above deck is subject to PSA requirements and N-004. The approval authority split is PSA for the topsides, and the DNV surveyor for the hull class items.

Documenting the split in the Basis of Design

Every dual-standard project must have a clear Basis of Design (BoD) document that specifies:

Which standard governs which structural system (with a system boundary drawing)
How interface/boundary structures are handled (typically: both standards checked, more conservative governs)
Which load standard applies for each system (N-003 vs DNV-RP-C205)
The approval authority for each system (PSA verifier vs DNV surveyor)
How design changes at the interface are managed (change control that triggers review under both standards)

Approval authority split Getting this wrong has consequences. If you submit a DNV-OS-C101-based design for PSA regulatory approval on an item that falls under N-004, PSA can reject it. Conversely, if you submit an N-004 calculation for DNV class approval on a hull structural item, DNV may reject it. Clarify the boundary and the certifying authority early — not during the IFC review.

9. Material requirements

Both N-004 and DNV-OS-C101 have companion material standards that specify approved structural steel grades. These are complementary — not contradictory — for the grades most commonly used offshore.

N-004 material references

N-004 references NORSOK M-001 (material selection) and NORSOK M-120 (material requirements for structural steel) as the governing documents for material specification. Key points:

Structural steels must comply with EN 10025 (hot-rolled) or EN 10210 (hollow sections) as the base product standard
NORSOK M-120 MDS sheets add NCS-specific requirements: tighter chemistry limits, mandatory Charpy impact testing (often at -40°C), supplementary ultrasonic testing for thick plates
Grade S355 (minimum yield 355 MPa) and S420 are the most common structural grades on NCS jackets and topsides
High-strength steel (S460 and above) requires additional requirements per M-120 and M-001 regarding HAZ toughness and welding

DNV-OS-C101 material references

DNV-OS-C101 references DNV-OS-B101 (metallic materials) as its companion material standard. DNV-OS-B101 similarly:

Approves grades from EN 10025, EN 10210, and equivalent recognized national standards
Specifies impact testing requirements by NV grade designation (NV Grade A, B, D, E, F for mild steel; NV Grade AH32 through FH40 for high-strength)
Sets through-thickness (Z-grade) requirements for plates subject to lamellar tearing risk

Grade compatibility between standards

For the most commonly used grades — EN 10025 S355 J2+N/M and S355 NL — both M-001/M-120 and DNV-OS-B101 accept the grade, typically with the same impact test requirements. This means material purchased to NORSOK M-120 MDS standards will generally also satisfy DNV-OS-B101 requirements at the same grade.

Common grade	N-004 / M-120 acceptance	DNV-OS-C101 / B101 acceptance	Note
S355 J2+N	Accepted	Accepted (NV D36 equivalent)	Standard topside structural grade
S355 NL	Accepted	Accepted (NV EH36 equivalent)	Low-temperature toughness for splash zone/Arctic
S420 ML	Accepted per M-120	Check B101 edition	Verify specific grade on DNV approved list
S460 ML	With M-120 MDS	With B101 Sec 4	High-strength: both standards require additional verification

For NCS projects where both N-004 and DNV-OS-C101 apply, verify that the chosen grade appears on both approved lists. For standard S355 and S420 this is almost always the case. For higher-strength grades or specialty products (TMCP plates, large-diameter hollow sections), verify explicitly and record the cross-standard compliance in the material traceability register.

Certificate requirements Both standards require EN 10204 Type 3.1 inspection certificates for primary load-bearing structural steel. Where both PSA regulatory and DNV class requirements apply to the same steel, the certificate must satisfy both. In practice, a 3.1 certificate from the steel mill — meeting both M-120 MDS and DNV-OS-B101 test requirements — covers both simultaneously. Agree this with the DNV surveyor and the operator's material engineer at the procurement stage.

10. Practical checklist — which standard governs?

Work through this checklist at the start of every offshore structural design project. Document the answers in the Basis of Design before detailed engineering begins.

Standard selection decision flow

Is the asset located on the Norwegian Continental Shelf (NCS)? If yes → NORSOK N-004 applies by PSA regulation for all fixed structural systems. Confirm by checking the production licence block number — if it falls within NCS boundaries, PSA jurisdiction applies.

Does the asset require DNV class? If yes → DNV-OS-C101 applies for all structures within the DNV class boundary. Check the class certificate scope of survey — it defines which systems are class items.

Is both A and B true? If yes → split by system boundary (hull → DNV-OS-C101, topsides/fixed installation → N-004). Document the boundary in the BoD. Interface structures are checked against both; the more conservative provision governs.

Is it a temporary or modular structure on an NCS asset? Check NORSOK Z-015 classification. If it is integral to the host facility's structural system → N-004 applies. If it is standalone temporary equipment with its own class → DNV-OS-C101 may govern the equipment frame, but host interface must comply with N-004.

Not NCS, not requiring DNV class? DNV-OS-C101 is the most common design basis by contract on non-NCS projects, or ISO 19902 for fixed steel offshore platforms in international waters. Confirm with the operator's contractual requirements and the flag state regulations.

Project setup checklist

Standard selection documented in Basis of Design — N-004, DNV-OS-C101, or both — with system boundary drawing
Load standard confirmed — NORSOK N-003 for NCS projects, DNVGL-RP-C205 for non-NCS or floating units outside NCS
ALS energy levels defined from NORSOK Z-013 risk analysis (NCS) or DNV class rules (class items)
Fatigue methodology confirmed — DNVGL-RP-C203 in both cases; DFF applied per inspection accessibility table
Tubular joint classification completed for all primary brace-chord connections; Efthymiou SCF validity ranges checked
Grouted connections (if any) designed per N-004 Annex A (NCS jackets) or DNV-OS-C106 (class)
Material grades verified on approved list for governing standard (M-120 for N-004, DNV-OS-B101 for DNV-OS-C101)
On dual-standard projects: material grades verified on both approved lists; 3.1 cert scope agreed with mill, operator, and DNV surveyor
Approval authority identified for each system — PSA verifier for N-004-governed items, DNV surveyor for class items
Change control process defined for interface structures — changes reviewed against both standards

Quick reference: standard by scenario

Scenario	Primary standard	Approval authority
NCS fixed jacket platform — jacket structure	N-004	PSA / PSA-approved verifier
NCS fixed platform — topsides primary structure	N-004	PSA / PSA-approved verifier
DNV-classed FPSO hull and mooring	DNV-OS-C101	DNV surveyor
NCS FPSO topsides process structure	N-004	PSA / PSA-approved verifier
DNV-classed semi-submersible — hull pontoons and columns	DNV-OS-C101	DNV surveyor
NCS semi-sub — permanently installed topsides above main deck	N-004	PSA / PSA-approved verifier
DNV-classed crane on NCS fixed platform — crane pedestal	Both N-004 + DNV-OS-C101	PSA verifier + DNV surveyor
Non-NCS fixed jacket — international waters	DNV-OS-C101 or ISO 19902	Per flag state / contract
Jacket refurbishment with grouted pile reinforcement	N-004 Annex A	PSA / PSA-approved verifier
Temporary structure on NCS asset (NORSOK Z-015 scope)	N-004 (if integral) or contract	PSA verifier or operator approval

DNV-RP-C205

Wave Load Calculations Primer

Morison's equation, JONSWAP spectrum, CD/CM selection, and design wave workflow.

ISO 2553 · AWS A2.4

Weld Symbols: ISO vs AWS

The notation differences that generate expensive NCRs on offshore fabrication projects.

NORSOK M-001

Material Selection for Offshore

Corrosion classes, duplex grades, PREN calculations, and HISC risk on the NCS.

Navigate N-004 and DNV-OS-C101 with AI

Leide's AI Navigator gives clause-cited answers from offshore engineering standards — query lifting appliance requirements, structural steel specs, and NCS regulatory requirements without hunting through PDFs. DNV-ST-0378, EN-10025-2, and more are already indexed.

Try the AI Navigator →

NORSOK N-004 vs DNV-OS-C101: When Each Applies

1. The regulatory hierarchy

When you have both on one project

2. NORSOK N-004 scope and applicability

3. DNV-OS-C101 scope and applicability

4. Key technical differences

Load factor alignment

5. Tubular joint design

Joint types and geometry

Stress concentration factors (SCFs)

Chord utilization ratio

Grouted joints — N-004 Annex A

6. Accidental limit state (ALS)

N-004 ALS — NCS regulatory context

DNV-OS-C101 ALS — class context

ALS analysis method

7. Fatigue design

Shared reference: DNVGL-RP-C203

Fatigue design life and DFF

Weld improvement techniques

8. Dual-standard projects

Documenting the split in the Basis of Design

9. Material requirements

N-004 material references

DNV-OS-C101 material references

Grade compatibility between standards

10. Practical checklist — which standard governs?

Project setup checklist

Quick reference: standard by scenario

Navigate N-004 and DNV-OS-C101 with AI