DNV DNVGL-RU-SHIPS PART 6 CHAPTER 1 PDF

• The scope of additional class notation Grab is to add an additional level of safety in relation to the strengthening of those parts of the hull structure that are exposed to impact loads from grabs. The rules in this section are considered to satisfy the requirements for determining the net thickness [strengthening] of structural elements, such as inner bottom and lower parts of transverse and longitudinal bulkheads; aligned with, and dependent upon, selected qualifiers as shown in Table 1.

• The scope of the rules in this section is considered to satisfy the requirements for strengthening of structural elements, such as weather deck hatch covers, weather decks and inner bottoms, within specified design load criteria, for ships loaded with heavy cargo. Design requirements related to external pressure, due to heavy distributed loads, are applied through ensuring compliance with DNV GL rules.

• The scope of the additional class notation HL is to satisfy the requirements for the strengthening of structural members of cargo tanks or holds that are exposed to heavy liquid loads. The design criteria includes strength assessment, related to static and dynamic liquid pressure, the application of design pressure loads for hull scantlings, and fatigue strength assessment related to given maximum design densities, primarily for ships intended for the carriage of heavy liquids.

• The scope of additional class notation HC is to add a further level of safety in relation to the strengthening of the hull structure, due to the carriage of dry bulk cargo. The rules in this section are considered to satisfy the design requirements based on the given rule defined maximum dry bulk cargo density and the rule defined loading flexibility, depending upon selected qualifiers, which are shown in Table 1.

This section includes requirements for hull strength, including:

— [3]: Pressures and forces due to dry bulk cargo

— [4]: Loading conditions

— [3]: Hold mass curves

— [6]: Hull local scantling

— [7]: Finite element analysis

— [8]: Buckling

— [9]: Fatigue

— [10]: Loading manual and loading instrument.

• Within the midship region, the connection between the inner bottom and the longitudinal bulkhead or hopper plating in way of floors, being a web-stiffened cruciform joint, shall be assessed in accordance with DNVGLCG-0129 Fatigue assessment of ship structure, [6.5.2].

Standard fatigue loading conditions as given in [4.3.1] shall be applied to the stress concentration model.

• The scope of class notation OC is to add an additional level of safety in relation to the strengthening of the hull structure due to the carriage of ore cargo. The rules in this section are considered to satisfy the design requirements based on the given rule defined loading flexibility, depending upon selected qualifiers, see Table 1.

This section includes requirements for hull strength, including:

— [3]: Pressures and forces due to dry bulk cargo

— [4]: Loading conditions

— [5]: Hold mass curves

— [6]: Hull local scantling

— [7]: Finite element analysis

— [8]: Buckling

— [9]: Fatigue

— [10]: Loading manual and loading instrument.

• The scope of additional class notation Plus is to add an increased level of safety related to additional fatigue strength assessment of hull structural details. The additional fatigue strength assessment includes fatigue strength calculations based on finite element analysis of selected fatigue critical details. The rules in this section are considered to satisfy the requirements for fatigue strength assessment in addition to those specified in main class requirements in combination with ship type requirements given in Pt.5, or CSR.

• The scope of additional class notation CSA (computational ship analysis) is to add a supplementary level of safety related to strength verification of longitudinal structural members, global transfer members and primary supporting members. Such verification design requirements include: loading conditions for fatigue and ultimate strength, wave load and finite element analysis, fatigue and ultimate strength analysis related to yield and buckling capacity and hull girder strength, respectively. The rules in this section are considered to satisfy the requirements for additional ultimate strength and fatigue assessment, in addition to those specified in main class requirements in combination with ship type requirements given in Pt.5, or CSR. An overall description is given in Table 1.

The additional class notation CSA has four different alternatives represented by specific qualifiers. Qualifier FLS1 represents the first level of the range of CSA notations, focusing on fatigue only. Qualifier FLS2 addresses fatigue limit state evaluations, but with a more comprehensive analysis scope. The CSA(1) and CSA(2) notations cover ultimate limit state assessment in addition to the fatigue strength assessments.

• The scope of additional class notation is to add a supplementary level of safety related to strength verification of longitudinal members, global transverse members and primary supporting members. Such verification design requirements include: loading conditions for fatigue and strength analysis, wave load and finite element analysis, fatigue assessment, strength assessment related to yield and buckling capacity and analysis of hatch cover movement. The rules in this section are considered to satisfy the requirements for global finite element analysis of the entire ship in verifying the structural adequacy of the longitudinal and transverse primary structure. In particular, the scantlings of members that are influenced by the torsional moment e.g. radii of the hatch corners, shall be checked based on the global finite element analysis. In case of optional RSD notation for container ships with rule length, L, less than or equal to 230 m, a reduced analysis scope is applicable, tailored for small and medium sized container ships.

• The scope of additional class notation COAT-PSPC is to add an increased level of safety related to corrosion prevention in tanks, areas and spaces, in accordance with specified coating system standards, aligned to statutory [SOLAS and MODU Code] requirements, and IMO/IACS interpretations. The rules in this section are considered to satisfy the requirements for corrosion prevention (coating) of tanks, spaces and areas, applicable for SOLAS and MODU Code compliant vessels, and when compliance with the IMO-PSPC standard has been requested by the owner. The design criteria includes a qualifier X, where X denotes additional requirements for; seawater ballast tanks, cargo oil tanks, double skin spaces and void spaces; for all types of vessel. A coating technical file [CTF] is required to be compiled by the shipyard and shall be reviewed by DNV GL, as shall the inspection agreement. Qualifications for coating inspectors, type approval and inspection requirements have also been included.

• Additional class notation COLL, with relevant qualifier, will be assigned under the provision that the ship has sufficient residual longitudinal strength in the damaged condition. Qualifiers 1 to 6 will be assigned based on the defined characteristic ratio of the critical deformation energies, see Table 3.

For general cargo ships and tankers, the notation COLL with a corresponding restrictive note in the appendix to the classification certificate may also be granted for individual compartments only.

• The class notation WIV (Wave Induced Vibrations) requires additional ultimate strength assessment and fatigue strength assessment to those specified in main class requirements in combination with ship type requirements given in Pt.5.

• High temperature liquid cargo are usually transported in independent cargo tanks. However integral cargo tanks may be used for moderate temperatures dependent of structural arrangement and strength. A list of cargoes which may be covered by these rules is given in [4].

Cargoes of different temperatures and natures shall not be carried simultaneously in adjacent integral tanks or in the cargo area unless especially investigated and accepted.

Temperature (heat balance) calculations for full-cargo conditions shall be carried in accordance with [3.2].

Thermal stresses in the cargo containment area with surroundings shall be determined and documented for integral tank systems, valid both for part-cargo and full-cargo conditions, see [3.2.4].

The definitions of integral tank or independent tank are given in Pt.5 Ch.6 Sec.1.

The design temperatures, design cargo density and design assumptions will be noted in the Appendix to Classification Certificate. This information shall be given in the loading manual.

• The scope of the rules in this section is considered to satisfy the requirements for strengthening of structural elements, such as bottom shell, bottom longitudinal stiffeners, girders and transverse floors, within specified design load criteria, for ships during NAABSA operations.