- Keywords: Rules and standards, Maritime
The 2015 July edition of GL rules and guidelines is now available at www.DNVGL.com
New and amended rules were formally approved on 18th June and are included in the 2015 July edition of the rules.
Below is given a general overview of the changes. For more detailed information, please view the links and/or contact your local DNV GL office for further information.
Rules for Seagoing Ships
- New Class Notation RSD (WiV) related to whipping and springing (I-0, Sec.2)
- Safe working load for shipboard fittings and supporting structures (I-1-1 & I-1-5, Sec.18)
- New requirements for spaces intended for the carriage of motor vehicles with compressed natural gas or compressed hydrogen in their tanks for their own propulsion as cargo (I-1-3, Sec.16)
- Fire suppression arrangements for on-deck cargo areas (Res. MSC.365(93) refers) (I-1-2, Sec.12)
- Survey requirements regarding spare parts removed from classification rules (I-0, Sec.2 to 5)
- Reduction factor introduced for ultimate strength check of bulk carriers in flooded condition (I-1-1, Sec.23)
- Applied draught in load case 2 for cargo hold analysis adjusted (I-1-5, Sec.36)
- Deck foam systems on tankers to be designed in accordance with the revised chapter 14 of the FSS Code (Res. MSC.339(91)) (I-1-2, Sec.12).
- Implementation of IACS UI SC270 relating to the capacity of main and emergency fire pumps (I-1-2, Sec.12)
Rules for Loading Gear on Seagoing Ships and Offshore Installations
- Editorial revision of these rules regarding content structure, readability and references (VI-2-2)
A few comments:
- The Class Notation RSD (WiV) (I-0, Sec.2, Table 2.10) has been established to enable explicit indication that a container ship has been assessed regarding wave-induced hull girder vibrations (whipping and springing).
The assessment will be based on the new DNV GL Class Guideline "Fatigue and Ultimate Strength Assessment of Container Ships including Whipping and Springing".
By meeting the requirements for the Class Notation RSD (WiV) owners/charterers can show that their ships have been subjected to additional assessments reducing risk of damages or loss due to wave-induced vibrations.
- Regarding shipboard fittings and supporting structures associated with towing and mooring (I-1-1 & I-1-5, Sec.18) the safe working load has been aligned with the applied SWL in the respective IACS Unified Requirement A2.
- All electrical equipment and wiring shall be of a certified safe type for use in an explosive hydrogen and / or methane and air mixture, fans shall be such as to avoid the possibility of ignition of such mixtures, other equipment which may constitute a source of ignition of such mixtures shall not be permitted.
For hydrogen the outlet of any exhaust duct shall be sited in a safe position, having no regard to other possible sources of ignition (I-1-3, Sec.16).
- Ships designed to carry containers on or above the weather deck are to be fitted with either a water mist lance or mobile water monitors, depending on container stowage capacity, in order to contain a fire in the space or area of origin and cool adjacent areas to prevent fire spread and structural damage (I-1-2, Sec.12).
- Survey requirements concerning spare parts will no longer be continued as rule requirements (I-0, Sec.2 to 5) because they are covered by statutory codes.
- According to IACS Unified Requirement S17 ultimate strength of bulk carriers in flooded condition needs to be calculated but does not take into account the structural damage which causes flooding.
To enable more realistic ultimate strength analysis the reduction factor κdm (subject to agreement between owner/shipyard and DNV GL) may be applied thereby taking the damage into consideration (I-1-1, Sec.23, C.2.2.1).
- Concerning Load Case 2 (I-1-5, Sec.36, Table 36.2) of the cargo hold analysis the applied draught has been increased to 0.9Tsc in line with the upcoming IACS Unified Requirement S34 "Functional Requirements on Load Cases for Strength Assessment of Container Ships by Finite Element Analysis".
The increase of applied draught in the GL rules corresponds to eased double bottom requirements (water pressure versus cargo load).