DNV Standards

DNV Standards

SDC Verifier implemented a bunch of DNV rules and regulations for offshore structures stability. It is possible to perform plate buckling check according to DNV CN30 (DNV Classification Notes no. 30.1. Buckling Strength Analysis, July 1995), plate buckling check and stiffener buckling check according to DNV RP-C201 (Recommended Practice DNV–RP-C201, Buckling Strength of Plated Structures, October 2010), weld strength check according to DNV OS-C101-LRFD (Design of Offshore Steel Structures, General (LRFD Method), April 2011) and DNV OS-C201-WSD (Structural Design of Offshore Units (WSD Method), April 2011), fatigue check according to DNV RP-C203 (Fatigue Design of Offshore Steel Structures April 2016), DNV-CG-0128 – Plate Buckling Standard, supporting both the October 2015 and December 2023 editions.

Buckling Strength Analysis (DNV CN30, July 1995)

Structural stability must be provided for the structure as a whole and for each structural member.

There are basically two ways in which a structure may lose its stability:

  • Snap-Through Buckling – it is characterized by a load-deflection curve. The structure collapses when the load is increased beyond the limit point.
  • Classical or Bifurcation Buckling. – for relatively small loads, the equilibrium state of the structure is called the pre-buckling state or the fundamental state. When the load is increased, a bifurcation point is reached, at which another solution to the equilibrium equations exists. Beyond the bifurcation point, the pre-buckling path is unstable. The post-buckling behaviour then depends on the characteristics of the secondary path.

Analysis of buckling strength must be based on the most unfavourable buckling mode’s characteristic buckling strength.

Read the help article on implementation of DNV CN30 Plate Buckling in SDC Verifier.

Buckling Strength of Plated Structures (DNV RP-C201, October 2010)

Two different but equally valid approaches are described in the document for evaluating the ultimate strength and buckling of plated structures.

The first technique uses a standard buckling code for stiffened and unstiffened steel panels. The stiffened flat plate section of the earlier DNV Classification Note No. 30.1 “Buckling Strength Analysis” (DNV CN-30) has been updated and developed. For plates, stiffeners, and girders, recommendations are provided.

The second technique uses the PULS (Panel Ultimate Limit State) computerized semi-analytical model. It is founded on a well-known non-linear plate theory, the discretization of deflections by Rayleigh-Ritz, and a numerical method for resolving the equilibrium equations.

Read the help article on implementation of DNV RP-C201 Plate/Stiffener Buckling in SDC Verifier.

Design of Offshore Steel Structures, General (LRFD Method), (DNV OS-C101, April 2011)

DNV-OS-C101 is the general part of the DNV offshore standards for structures. It provides principles, technical requirements and guidance for the structural design of offshore structures and applicable to all types of offshore structures of steel. The standard is primarily intended to be used in design of a structure where a supporting object standard exists, but may also be used as a stand-alone document for objects where no object standard exist.

This regulation is based on the load and resistance factor design method. Structures and structural elements shall be designed to:

  • Sustain loads liable to occur during all temporary, operating and damaged conditions, if required
  • Maintain acceptable safety for personnel and environment
  • Have adequate durability against deterioration during the design life of the structure.

Read the help article on implementation of DNV OS-C101-LRFD Weld Strength in SDC Verifier.

Structural Design of Offshore Units (WSD Method), (DNV OS-C201, April 2011)

This offshore standard provides principles, technical requirements and guidance for the structural design of offshore structures, based on the Working Stress Design (WSD) method.

This regulation has been written for general world-wide application. Statutory regulations may include requirements in excess of the provisions by this standard depending on size, type, location and intended service of the offshore unit or installation.

This section describes design principles and design techniques including:

  • Working stress design method
  • Design assisted by testing
  • Probability based design

Read the help article on implementation of DNV OS-C201-WSD Weld Strength in SDC Verifier.

Fatigue Design of Offshore Steel Structures, (DNV RP-C203, April 2016)

This recommended practice presents recommendations in relation to fatigue analyses based on fatigue tests (S-N data) and fracture mechanics.

The goal of fatigue design is to ensure that the structure has a sufficient fatigue life. Calculated fatigue lives also form the basis for efficient inspection programmes during production and the operational life of the structure.

DNV RP-C203 is valid for carbon manganese steel materials (C-Mn) in air with yield strength less than 960 MPa.

Read the help article on implementation of DNV RP-C203 Fatigue in SDC Verifier.

Fatigue Design of Offshore Steel Structures, (DNV RP-C203, October 2024 edition)

SDC Verifier now supports fatigue analysis according to DNV RP-C203 Fatigue (2024), an industry-recognized standard for assessing the fatigue life of offshore steel structures. This standard provides methodologies for evaluating fatigue damage, ensuring structural integrity under cyclic loading conditions. 

Objective 

The primary goal of DNV RP-C203 is to prevent fatigue failures by providing calculation methods based on S-N curves (fatigue test data) and fracture mechanics. The standard helps engineers design structures that can withstand cyclic stresses over their intended lifespan, reducing risks associated with fatigue-induced failures. 

Scope 

DNV RP-C203 applies to carbon-manganese (C-Mn) steel materials with a yield strength of less than 960 MPa and is specifically designed for: 

  • Offshore platforms 
  • Marine structures 
  • Steel bridges 
  • Wind turbine foundations 
  • Any structure subject to repetitive loading 

The standard outlines procedures for stress-life (S-N curves), which are widely used for evaluating the fatigue life of welded and non-welded joints. 

Implementation in SDC Verifier 

With the 2024 R2 release, SDC Verifier integrates fatigue checks based on DNV RP-C203, allowing engineers to: 

✅ Perform automated fatigue calculations using S-N curve methodology. 
✅ Evaluate fatigue life under different stress ranges and load conditions. 
✅ Apply weld classification for accurate fatigue assessments. 
✅ Improve structural reliability by identifying critical fatigue-prone areas. 

The implementation enhances accuracy and efficiency, reducing manual workload while ensuring compliance with offshore engineering standards. 

Application 

Engineers and designers working on offshore and maritime structures benefit from this standard as it helps in: 

  • Early detection of fatigue issues, allowing preventive maintenance. 
  • Design optimization to extend the operational life of structures. 
  • Meeting certification requirements for offshore construction and safety. 

Helpful Links 

DNV OS-C101-LRFD Weld Strength (2024)

SDC Verifier now supports DNV OS-C101-LRFD Weld Strength (2024), based on Chapter 2, Section 5 of DNV’s July 2024 Offshore Structural Design Standard. This standard covers direct weld strength checks for offshore structures using the LRFD (Load and Resistance Factor Design) method.

Objective

The goal of this standard is to assess the structural strength of welded connections in offshore units under factored load combinations. It ensures weld capacity checks are based on actual stress conditions, geometry, and material strength, as required by DNV regulations.

Scope

This standard applies to:

  • Welded joints in offshore structures, such as topsides, decks, and support frames
  • Welds in load-bearing components, including connections in liquid cargo tanks and ballast tanks
  • Design checks for tension, bending, and shear in welds under factored load combinations

Checks are based on throat stresses and material properties. Eccentricity effects in single fillet welds are also accounted for where relevant.

Implementation in SDC Verifier

With the 2025 R1.1 update, SDC Verifier enables full automation of DNV OS-C101-LRFD Weld Strength checks, including:

✅ Geometry-based weld dimension extraction and section property calculation
✅ Direct throat stress evaluation at multiple locations along the weld length
✅ Optional inclusion of eccentricity moment for single fillet welds
✅ Support for material-specific factors like:  
• Beta_w – correlation factor (Table 4)  
• Gamma_Mw – partial safety factor for welds (Table 5)  
• Gamma_M – material resistance factor (= 1.15)

The software also flags welds that do not meet minimum leg length requirements and checks for correct material property definitions (yield/tensile) during setup.

Application

This standard is relevant to structural engineers working on:

  • Offshore oil & gas structures following DNV classification
  • Welded joint validation in LRFD-based design workflows
  • Projects requiring automated weld verification for certification

It simplifies weld compliance in demanding design environments where LRFD methodology is required and helps eliminate manual calculation errors during connection design.

Read the help article on the implementation of DNV OS-C101-LRFD Weld Strength in SDC Verifier

DNV OS-C101-WSD Weld Strength (2024)

SDC Verifier now includes support for DNV OS-C101-WSD Weld Strength (2024), based on Chapter 2, Section 5 of the July 2024 edition of DNV’s Offshore Structural Design Standard. This implementation covers weld checks using the WSD (Working Stress Design) method.

Objective

This standard provides a method for verifying weld strength in offshore structures under unfactored load conditions. It defines stress limits and safety factors for various types of welds and structural connections, ensuring they remain within allowable working stress levels.

Scope

This standard applies to:

  • Welded joints in topside structures, frames, and decks
  • Structural connections in liquid cargo tanks and ballast tanks
  • Direct weld checks using working stress design methodology

Welds are assessed based on stress at the weld throat, material properties, and defined safety factors from the DNV code.

Implementation in SDC Verifier

As of the 2025 R1.1 release, SDC Verifier automates all major components of the DNV OS-C101-WSD weld strength assessment:

✅ Calculates geometry-dependent properties (weld area, elastic section modulus)
✅ Evaluates weld throat stresses at both ends of the connection
✅ Includes optional eccentricity moment in single fillet welds
✅ Applies DNV-defined safety factors, including:  
• Beta_w – correlation factor for material type (Table 4)  
• Eta₀wₐ / Eta₀w_b – basic safety factors for direct weld equations (Table 5)  
• Gamma_M – material resistance factor (= 1.15)

Warnings are issued if weld leg lengths are below minimum values. The software also verifies that material yield and tensile strength are correctly defined.

Application

This standard is intended for engineering teams working on:

  • Offshore projects using WSD methodology under DNV classification
  • Weld verification where factored design (LRFD) is not applicable
  • Detailed design validation of structural welds in compliance with DNV 2024 updates

It enables direct application of code-based checks with full traceability and no need for manual stress transformations or correction factors.

Read the help article on the implementation of DNV OS-C101-WSD Weld Strength in SDC Verifier

DNVGL-ST-0126 (2016)

SDC Verifier supports DNVGL-ST-0126 (2016), a structural design guideline for offshore structures issued by DNV. This standard acts as a referencing framework that connects specific structural components to their respective calculation methods from established design codes.

Objective

The purpose of DNVGL-ST-0126 is to provide a unified design framework for offshore units by referencing validated design standards for each structural element. It defines the applicable checks for different connection types, members, and components based on function and geometry.

Scope

This standard is applicable to all types of onshore and fixed offshore support structures for wind turbines.

The standard is applicable to the design of complete structures, including towers, substructures and foundations, but excluding wind turbine components such as nacelles and rotors.

Referenced Standards Implemented in SDC Verifier

DNVGL-ST-0126 relies on the following calculation procedures, all of which are available in SDC Verifier:

Buckling:

  • Eurocode 3 Members (EN 1993-1-1)
  • Eurocode 3 Plate Buckling (EN 1993-1-5)

Tubular Members:

  • Eurocode 3 Members (EN 1993-1-1)
  • ISO 19902 (1st, 2007)
  • NORSOK N004 (rev.3, 2013)

Bolted Connections:

  • Eurocode 3 Bolts (EN 1993-1-8)

Welded Connections:

  • DNV OS-C101-LRFD Weld Strength (2011)
  • DNV OS-C201-WSD Weld Strength (2011)

Tubular Joints:

  • ISO 19902
  • NORSOK N004

Non-Tubular Frames and Beams:

  • DNV RP-C201 Plate/Stiffener Buckling (2010)
  • Eurocode 3 Members (EN 1993-1-1)

Plates:

  • Eurocode 3 Plate Buckling (EN 1993-1-5)

Fatigue:

  • DNV-RP-C203 Fatigue (2016)
  • Eurocode 3 Fatigue (EN 1993-1-9)

Application

DNVGL-ST-0126 is intended for structural engineers working on offshore units that require traceable and documented compliance with DNV’s offshore design rules. Rather than introduce new formulas, it ensures that existing standards are correctly applied to the relevant parts of a structure.

Using this standard within SDC Verifier allows you to organize your verification workflow according to DNV’s structural categorization logic, ensuring every element is checked against the appropriate design rules.

Read the help article on the implementation of DNVGL-ST-0126 in SDC Verifier.

DNV-CG-0128 – Plate Buckling Standard (October 2015 and December 2023 editions)

SDC Verifier has extended its capabilities to include the DNV-CG-0128 standard, supporting both the October 2015 and December 2023 editions. This standard outlines the criteria for assessing the buckling and ultimate strength limits (ULS) of load-carrying members, with a focus on unstiffened plate buckling. 

Objective
DNV-CG-0128 provides methodologies and principles for the assessment of buckling and ultimate strength limits of structural components, particularly those used in ship hulls and similar plated constructions. The primary objective of these criteria is to ensure robust design and controlled behavior of structures under loading conditions defined by the classification rules for ships and offshore units. 

Scope 
This guideline defines several methodologies for evaluating buckling and ULS, including but not limited to: 

  • Closed Form Method (CFM): Section 3 outlines the CFM for assessing the buckling capacity of unstiffened plates, which is the primary method implemented in SDC Verifier. 
  • CFM for Struts, Pillars, and Beam-Columns: Guidance for these structural elements is also provided in the standard but is not currently implemented in SDC Verifier. 
  • Semi-Analytical Buckling Models (PULS): These models cover both stiffened and unstiffened plates and are discussed in Section 4. 
  • Ultimate Hull Girder Capacity: Section 5 addresses the overall buckling capacity of ship hull girders. 
  • Non-Linear Finite Element Analysis (FEA): Section 6 includes guidelines for using non-linear FEA to assess structural capacity. 

Application
This guideline applies to the buckling strength assessment of metallic structures in vessels designed in compliance with DNV-RU-SHIP and DNV-RU-OU standards for various offshore unit types. The implemented section focuses on the CFM for unstiffened plates, offering a reliable and efficient means to evaluate the buckling capacity of these structural elements. 

Read the helpful articles on the implementation of DNV CG-0128 Plate Buckling (2015) and DNV CG-0128 Plate Buckling (2023) in the SDC Verifier.

Info on DNV Standards

Det Norske Veritas (DNV) Offshore Codes include Offshore Standards providing technical provisions and acceptance criteria for general use by the offshore industry as well as the technological basis for DNV offshore services.

DNV is an autonomous and independent foundation that undertakes classification, certification, and other verification and consultancy services relating to the quality of ships, offshore units, and installations, and onshore industries worldwide and carries out research about these functions.