The January 2001 edition of the Rules for Classification of High Speed, Light Craft and Naval Surface Craft contains the following existing, new and renumbered rule chapters:
Pt.0 Ch.1 User Information, Amendments and Indexes
Pt.1 Ch.1 General Regulations
Pt.2 Ch.2 Metallic Materials
Pt.4 Ch.1 Machinery and Systems, General (new)
Pt.4 Ch.2 Rotating Machinery, General (new)
Pt.4 Ch.3 Rotating Machinery, Drivers (new)
Pt.4 Ch.4 Rotating Machinery, Power Transmissions (new)
Pt.4 Ch.5 Rotating Machinery, Driven Units (new)
Pt.4 Ch.6 Machinery Piping Systems (new)
Pt.4 Ch.7 Boilers, Pressure Vessels, Thermal-Oil Installations and Incinerators (new)
Pt.4 Ch.8 Electrical Installations (renumbered)
Pt.4 Ch.9 Instrumentation and Automation (renumbered)
Pt.4 Ch.10 Fire Safety (renumbered)
Pt.4 Ch.11 Safety of Navigation (renumbered)
Pt.4 Ch.12 Radio Communications (renumbered)
Pt.4 Ch.13 Control and Monitoring of Propulsion, Directional Control, Stabilisation and Auxiliary Systems (renumbered)
Pt.5 Ch.2 Car Ferry
Pt.6 Ch.5 Integrated Computer Systems (ICS)
Pt.7 Ch.2 Periodical Survey Requirements
From January 2001 the following existing rule chapters from the Rules for Classification of High Speed, Light Craft and Naval Surface Craft are withdrawn:
Pt.4 Ch.1 Machinery and Hull Piping Systems (renamed)
Pt.4 Ch.2 Propulsion, Auxiliary Machinery and Pressure Vessels (renamed)
Pt.4 Ch.3 Control and Monitoring of Propulsion, Directional Control, Stabilisation and Auxiliary Systems (renumbered)
Pt.4 Ch.4 Electrical Installations (renumbered)
Pt.4 Ch.5 Instrumentation and Automation (renumbered)
Pt.4 Ch.6 Fire Safety (renumbered)
Pt.4 Ch.7 Safety of Navigation (renumbered)
Pt.4 Ch.8 Radio Communication (renumbered)
In addition, some of the rule chapters have been subject to amendments, which have been inserted in Sec.3 of Pt.0 Ch.1. The changes come into force 1 July 2001.
Important rule changes
The rule changes covered by the revised chapters or Sec.3 of Pt.0 Ch.1 are as follows:
Pt.4 Ch.1 Machinery and Systems, General
Piping related requirements have been taken out of Pt.4 Ch.1 and have been moved to the new chapter (Pt.4 Ch.6 "Machinery Piping Systems"). The new Ch.6 is "self-contained" and the new general Pt.4 Ch.1 is a superior chapter for Pt.4 Ch.2 to Pt.4 Ch.12.
Pt.4 Ch.1 Sec.1 Machinery and Systems, General - General Requirements
Some of the definitions are deleted and some are moved to other relevant chapters. The explanation of the term Redundancy is expanded.
Pt.4 Ch.1 Sec.2 Machinery and Systems, General - Materials
Piping related material requirements have been moved to the new Ch.6.
Pt.4 Ch.1 Sec.3 Machinery and Systems, General - Design Principles
The requirements for redundancy on different levels are explained with requirements for minimum output power after single failure. The rule text is "tuned" to fit all types of machinery systems (also electrical). Example of the interpretation of the rule is given in a guidance note.
Guidance note on materials with high heat resistance is included.
Pt.4 Ch.1 Sec.4 Machinery and Systems, General - Spare Parts
New rule text on spare parts with guidance note is added.
Pt.4 Ch.2 to Ch.5 Rotating Machinery (new)
The main class rules for rotating machinery have been completely re-written and are now distributed in three chapters. The main reasons for the amendments are as follows:
The rules shall have a life cycle focus in the class involvement:
The ship in operation phase should be as problem-free as possible.
Requirements shall specified as early as possible to detect unacceptable designs or defects.
It shall be a connection in the DNV involvement in the different phases (design, production, installation and operation).
Built-in design safety shall not be reduced during production and installation.
The rules shall be customer or user friendly and transparent:
Acceptance criteria have been used wherever possible to ensure that the customers know what DNV will accept, what DNV will reject and why.
Important requirements that have been hidden in internal instructions should be included.
The 1A1 rules shall be improved based on experience and criticality of each component or system.
Pt.4 Ch.2 Rotating Machinery, General (new)
This is a new chapter. See general motives above. This chapter is a common denominator for the three following chapters. It contains important principles as well as explanations on how to fulfil certification requirements. The purpose is to give support on how to apply basic requirements in Pt.1 Ch.1 for rotating machinery. In every section in the following three chapters there are references to Ch.2. The sections are:
Sec.1 Introduction
Sec.2 Certification Principles
Sec.3 Design and Documentation
Sec.4 Material and Material Testing (Preliminarily. Will be replaced by revised Pt.2.)
Sec.5 Special Materials and Processes (Preliminarily. Will be replaced by revised Pt.2.)
Sec.6 Electric Power Generation
Special attention should be paid to Sec.2 stating that for small auxiliary machinery, the product certification may, upon special evaluation and acceptance, be waived for power ratings less than 200 kW and rated torque less than 5 kNm.
Pt.4 Ch.3 Sec.1 Rotating Machinery, Drivers (new) - Diesel Engines
Turbocharger rules are revised and included in diesel engine section. Vibration requirements and methods for vibration calculation are included in the diesel engine section. Instrumentation requirements are increased to approximately E0 level. More focus is given on acceptance criteria and transparency on what DNV does. Involvement is based on criticality, life cycle focus and problem areas.
Pt.4 Ch.3 Sec.2 Rotating Machinery, Drivers (new) - Gas Turbines
The rules are more detailed than the previous edition, subsection A introduces the concept of system approval (as opposed to component approval) and presents a comprehensive list of documentation to be submitted. Particular attention is given to system integration.
The extensive design section comes as an answer to engine manufacturers as to better explain and present the approval exercise performed in DNV. While the New Machinery Project philosophy and methodology forms the basis for the revision, the main change is that a significantly more detailed and precise description of DNV requirements is provided.
The main improvements relate to the test requirements in general, and type testing in particular. Cycle-based testing represents the improvement in DNV's expertise towards gas turbine in-service operation. As modern ships, and in particular high speed ferries, use gas turbine propulsion with operating cycles including frequent start and stop sequences, it is necessary to introduce this aspect in the testing phase of new engines.
For inspection and testing, production verification process and extent of manufacturing survey arrangement are presented.
Following the same philosophy as type testing, cyclic loading is introduced in the certification test requirements for workshop testing. Less stringent than type testing, certification testing focuses on the operating profile each specific engine is intended for.
The extended list of control and alarms reflects the experience gathered in the past years on ships operating with gas turbine propulsion. Furthermore the concept of availability, in addition to safety, is highlighted and leads to changes in alarm logic. Specific fire safety requirements are introduced and strengthened, based on our acquired experience with fire incidents on gas turbine equipped vessels.
The requirements to arrangement have been clarified and made more precise based on accumulated experience. More precise requirements to gas turbine enclosures are provided.
The vibration subsection lists analysis and measurements to be performed with reference to the relevant rules sections. While the specific requirements are located elsewhere in the document this section functions as a look-up list for the relevant requirements.
Working as a checklist, the installation inspection subsection is intended to verify that the general arrangement of the gas turbine propulsion system onboard the ship is in compliance with rule requirements of other sections.
Shipboard testing cover both quay and sea trials. This subsection is designed to verify system integration and control system behaviour.
Pt.4 Ch.4 Sec.1 Rotating Machinery, Power Transmissions (new) - Shafting
A new basic method for calculation of shaft dimensions covering modern fatigue theory, design and production is described in a new Classification Note No. 41.4. Three new simplified methods replaces today’s method for quick, simple and safe assessment of shaft dimensioning. Involvement is based on criticality, life cycle focus and problem areas. Examples of application of the new basic method is presented in an Appendix to Classification Note 41.4
Pt.4 Ch.4 Sec.2 Rotating Machinery, Power Transmissions (new) - Gear Transmission
For welded gear wheel designs, either stress intensity limitation or specific stress levels combined with different weld qualities are included. Criteria against fretting are included. Criteria for elasto-plastic shrinking included. Inspection and testing updated are more in line with ISO 6336-5. Requirement for contact test in work shop testing of bevel gears (when necessary, under slow turning with full load applied) is included. Alarm and instrumentation requirements are updated to today’s standard. More focus on acceptance criteria and transparency on what DNV does. Involvement is based on criticality, life cycle focus and problem areas.
Pt.4 Ch.4 Sec.3 Rotating Machinery, Power Transmissions (new) - Clutches
The rules are updated to instruction to surveyor level. Monitoring updated to a reasonable minimum (already common practice in the industry).
Pt.4 Ch.4 Sec.4 Rotating Machinery, Power Transmissions (new) - Bending Compliant Couplings
Bending compliant couplings are separated from elastic couplings in a separate section. Type testing requirements are updated to today’s practice. Requirement for emergency claws is replaced by monitoring (twist alarm).
Pt.4 Ch.4 Sec.5 Rotating Machinery, Power Transmissions (new) - Torsionally Elastic Couplings
Type testing requirements are updated to today’s practice. Requirement for emergency claws is replaced by monitoring (twist alarm).
Pt.4 Ch.4 Sec.6 Rotating Machinery, Power Transmissions (new) - Elements of Composite Materials
Elements of composite materials will be considered on a case by case basis.
Pt.4 Ch.4 Sec.7 Rotating Machinery, Power Transmissions (new) - Jacking Machinery
Safety factors for storm holding loads are reduced. Provision for acceptance of approved full scale testing as a substitute and/or supplement to design calculations is included. Evaluation of brakes, connections and flexible mounting are included.
Pt.4 Ch.5 Sec.1 Rotating Machinery, Driven Units (new) - Propellers
The criteria for dimensioning of propeller blades are completely revised and made appropriate for modern propeller designs. The focus has moved from "required thickness" to stresses (relative allowable stresses). This will, for instance, simplify the approval process if approval is to be based on finite element calculations. In average, propeller blade scantlings will be about the same as previously.
Scantling criteria for propeller blades are taken out of the rules and are now given in a separate classification note 41.5 where:
influence of profile thickness on fatigue properties is included
material parameters are revised, reflecting more realistic values
dynamic stress factor (mt) is revised according to existing experience
influence of propellers skew on stresses is included
influence of sectional profile on stresses is included
centrifugal stresses are normally neglected
requirement for tip-thickness is included
additional low-cycle criteria is included for propellers with reversible direction of rotation
more detailed description of how to handle propeller blades for tunnel thrusters is included.
Simple dimensioning criteria for pitch control mechanism are presented. These are mainly based on existing practise. The list of requested documentation is revised and given in a table. Table of required instrumentation and alarms are listed. For propellers with Baltic ice class, existing practice regarding reduction in ice torque for nozzle propellers has been included.
Pt.4 Ch.5 Sec.2 Rotating Machinery, Driven Units (new) - Water Jets
Requirements are included to secure that water jets do not experience loads for which they have n
In the installation phase: Focus on manufacturing of ducting as this greatly defines hydrodynamic operating conditions. In the operation phase: Control system indications and request for slow down when operating outside design assumptions.
Pt.4 Ch.5 Sec.3 Rotating Machinery, Driven Units (new) - Thrusters
Auxiliary thrusters of 300 kW or less no longer subject to design approval. Manufacturer shall submit information about any operational limitations, his design criteria and load assumptions. A guidance note indicating load cases and number of load cycles have been added. Strength and fatigue requirements for steering column have been added. Leakage detection for column seal at hull penetration has been added. Lifetime requirement for rolling bearings has been added. Minimum requirements for the lubrication system have been added. Exemption from certification granted for mass produced reduction gear boxes, which can easily be replaced. Applicable only for thrusters with two or more steering gear actuators and when the vessel is fully manoeuvrable with one thruster out of operation. Certification requirements for shafting have been harmonised in the different rule sections and the requirements are now given in Pt.4 Ch.4 Sec.1. Function testing is required for all hydraulic systems. Alarms and indications required are listed in a table. Azimuth thrusters shall be mounted in a watertight compartment if hull penetration is below deepest loaded waterline. Lower limit for application factor for propulsion plant is given.
Pt.4 Ch.5 Sec.4 Rotating Machinery, Driven Units (new) - Compressors
This section has only been subject to minor changes.
Pt.4 Ch.6 Piping Systems (New)
Piping related requirements have been taken out of the existing Pt.4 Ch.1 and have been moved to this new chapter. The changes introduced in addition to the editorial amendments are as described in the following.
The definition of pipe class has been modified to reflect the latest changes in IACS unified requirements. Requirements for flame spread characteristics in line with IMO Res. A.653(16) have been added for plastic pipes. The requirements regarding drip trays and remote stop of pumps have been moved from fuel oil systems to a higher level, to make it clearer that these rules also are applicable to other flammable liquids. Requirements for lubrication oil separators have been added for vessels burning residual oils. Based on experience feedback, a requirement has been added for bypass arrangements where flow meters are installed in the fuel oil supply system. A further requirement has been added, stating that flexible hoses carrying flammable fluids shall be type approved. Acceptance of pipe couplings has been modified in line with IACS unified requirements. Sec.4 Ship Piping Systems on air pipes has been modified to reflect the latest SOLAS amendment to air pipes, from fuel oil service tanks. Requirements for hydraulic testing of fuel oil tanks have been deleted in Sec.5 Machinery Piping Systems and have been transferred to Pt.3 Ch.1 Sec.1 or Pt.3 Ch.2 Sec.1, as appropriate. Additionally, requirements for pneumatic and hydraulic equipment, currently included in existing Pt.4 Ch.5 Sec.5 D, are moved to the new Pt.4 Ch.6 Sec.5.
Pt.4 Ch.7 Sec.1 Boilers, Pressure Vessels, Thermal-Oil Installations and Incinerators - General Requirements (new)
The requirements for documentation of thermal-oil installations are amended. In addition, an item "overpressure protection for condensers" is added in the section on documentation. Condensers, vacuum and atmospheric is clarified as being Class III pressure vessels.
Pt.4 Ch.7 Sec.3 Boilers, Pressure Vessels, Thermal-Oil Installations and Incinerators - Arrangement (new)
It is now required that oil fired thermal-oil heaters not located in separate rooms are to be surrounded by coamings of height not less than 150 mm and with drainage to a closed tank.
The use of bellows or similar expansion elements in thermal-oil piping is not permitted within machinery spaces.
Clarification regarding the intended use of the exhaust bypass requirement for exhaust heated thermal-oil heaters is added.
A requirement for remote operation of the valve for fast gravity discharge of thermal-oil is introduced.
Pt.4 Ch.7 Sec.6 Boilers, Pressure Vessels, Thermal-Oil Installations and Incinerators - Mountings and Fittings (new)
Specific requirements for acceptable means for protection of overpressure for vacuum condensers and atmospheric condensers are added.
Pt.4 Ch.8 Electrical Systems
This chapter is completely rewritten. The main changes are:
Restructuring
The main change to the rules is a restructuring:
The Rules for Classification of Ships and the Rules for High Speed, Light Craft and Naval Surface Craft are co-ordinated into one unified set of requirements.
Formal requirements related to the Society's work process form Sec.1, and are divided into three different tasks forming the complete verification scheme.
Approval of the electrical system.
Certification of the electrical equipment (Approval and product survey).
Site survey.
Technical requirements for electrical systems are separated from the requirements for equipment and components. This enables a clear set of requirements being imposed on the various stages of design and manufacturing.
Certification requirements
General: Revised limits for when a product certificate is required.
Medium range machines and transformers: A type approval certificate combined with works certificate may replace a NV product certificate.
Electrical systems: Introduction of the possibility for type approval of electrical distribution systems.
Documentation
New requirements for documentation are implemented. Focus is on information, no specific requirements for specific documents (or document names) are given. The tables are meant as a vehicle for information.
Technical requirements
Technical requirements have been updated where found necessary to keep abreast of the development in international standards. A change of technical requirements has not been the main issue of this revision. Some of the implemented changes are:
Requirements for protection of emergency generator are added, as well as a requirement for an alarm when the emergency generator is disabled from starting.
Updated terminology and clarified requirements for breaking capacity of circuit breakers.
Acceptance of reduced distances for clearance and creepage when LV assemblies are type tested of partially type tested.
Transformers with forced cooling are accepted.
Requirements for class 5 conductors are added, in line with IEC.
Today's prohibition against splicing of certain cables in junction boxes is deleted.
Today's requirement about stripped back length of cable outer sheath is deleted.
A new section for installations in hazardous areas in line with IEC, is added.
Pt.4 Ch.9 Sec.1 Instrumentation and Automation - General Requirements
The documentation requirements have been modified. The scope of documentation is about the same, but some document types have been deleted and their items have been combined with other document types.
Pt.4 Ch.9 Sec.5 Instrumentation and Automation - Component Design and Installation
A new location class for electromagnetic compatibility (emission) has been introduced into the rules. This is to take into account the different requirements for electromagnetic emission on the bridge or open deck and other locations.
Pt.4 Ch.10 Fire Safety
A general reference to IMO MSC/Circ.911 Interpretations of fire protection-related provisions of the HSC Code has been added. Items of IMO MSC/Circ. 911, which are regarded to be requirements rather than interpretations, have been included in the rules. Such requirements have mainly replaced existing text. Where the reference "new HSC Code" is used, this shall be understood as "Draft International Code of Safety for High-Speed Craft, 2000". Items from the draft Code are implemented where they reflect today’s interpretations or practices. New requirements of the draft Code are, in general, not implemented, yet.
Pt.5 Ch.1 Sec.4 Passenger Craft - Fire Safety
A reference is added to IMO MSC/Circ.912 Interpretation of standards for fixed sprinkler systems for high-speed craft (Resolution MSC.44(65)).
Pt.5 Ch.2 Sec.4 Car Ferry - Fire Safety
A reference is added to IMO Res. A.123(V) Recommendation on Fixed Fire Extinguishing Systems for Special Category Spaces or IMO MSC/Circ. 914 Guidelines for approval of alternative fixed water-based fire-fighting systems for special category spaces and a general reference to IMO MSC/Circ.911 Interpretations of fire protection-related provisions of the HSC Code has been added.
Pt.5 Ch.4 Sec.4 Crew Boats - Machinery and Systems
Craft with an overall length of less than 40m need not to be fitted with a second fire pump if the main fire pump is installed in a space protected by a fixed fire extinguishing system.
Pt.5 Ch.5 Sec.4 Yacht - Machinery and Systems
Specification of areas to be covered by automatic and manual sprinkler systems is given. The system need not to be provided with redundant pumps or back-up pressure tanks.
Craft with an overall length of less than 40m need not to be fitted with a second fire pump if the main fire pump is installed in a space protected by a fixed fire extinguishing system.
Pt.5 Ch.6 Sec.4 Patrol Boats - Machinery and Systems
Craft with an overall length of less than 40m need not to be fitted with a second fire pump if the main fire pump is installed in a space protected by a fixed fire extinguishing system.
Pt.7 Ch.2 Sec.1 Periodical Survey Requirements - General Requirements
New requirements for gas turbine maintenance have been given.
Pt.7 Ch.2 Sec.2 Periodical Survey Requirements - Survey Extent - Main Class
New requirements for surveys of gas turbines and water jets have been added.
Pt.7 Ch.2 Sec.3 Periodical Survey Requirements - Survey Extent, Additional Class
The survey requirements for integrated computer systems have been revised.