< Previous | Contents | Next >
Section 6 Design and Construction
601. General
1. ROV's and their components are to be designed for the conditions in which the specification states that they are to be used.
2. ROV's are to be designed and constructed in such a way as to ensure safe operation and allow proper maintenance to be carried out.
3. ROV's are to be so equipped that the dive operator is able to determine its position and operating condition.
4. ROV's which operate with diver support are to be equipped with a TV unit for monitoring the work site and with an EMERGENCY STOP device which can be operated from the ROV dive control station.
5. Due care is to be taken to ensure that inadvertent movements cannot cause the ROV to destroy it- self or equipment located at the work site or to become separated from its control and supply lines.
6. ROV's are to be designed that they respond in a defined manner (e.g. by positive buoyancy) to a failure of the control and power supply system.
7. Measures are to be taken which as far as possible prevent the ROV from becoming trapped.
Propellers are to be provided with suiTable protective devices.
602.
Ambient Conditions
1. The design, selection and arrangement of all machines, devices and equipment located on board ROV's shall, as a minimum requirement, be governed by the following ambient conditions. Other ambient conditions may be approved for ROV's which are usded only in restricted areas.
2. For inclined position, faultless operation is to be guaranteed at inclinations of up to 22.5 degree (static and dynamic) relative to the mounted position in any direction. Transitory inclinations of up to 45 degree shall not give rise to any undesirable functional changes or damage, particularly to the bearings of machines.
3. Fpeorratwuraeterr,anthgee d-e2s℃ign toof +R3O2V℃'s awnidthcoampsaolninenittys iosf g3e5neprpalmly atondbedebnassietdy oofn 10se2a8wkagtĤemr Ė.inA thraetiotemof-
0.101 bar/m is to be used for converting diving depth to pressure.
For sea state, the launching and recovery system for ROV's is to be designed for a sea state with
4. a significant wave height of at least 2 m. Allowance is to be made for accelerations of 2 g in the
Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015 29
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
vertical direction and 1 g each (g G ŊĦĒË mĤsË) in the transverse and lo longitudinal direction.
5. For climatic conditions, the transport, maintenance, inspection and dry testing of ROV's on board the supply ship and the launching and recovery system for the ROV are to be based on salty air
in the temperature range from -10℃ to +55℃ with a relative humanity of 100%.
6. mFoardethfeorpraotreecltaetdivedivheumcaonnittryolofro8o0m%s foatr aROreVfe'srenincsetatlelemdpeornatubroearodf s4u5p℃ply.
ships allowance is to be
For explosion protection, ROV's intended for use in or from areas subject to an explosion hazard
7. (e.g. oil or gas production platforms) are to be provided with suiTable explosion protection.
For other ambient conditions, where appropriate, the design of the ROV should also take account
8. of the ambient conditions occurring during possible transport by air (low pressure).
603.
Materials
1. Materials for ROV's and their equipment shall be so selected that the ROV can be safely operated throughout its planned life under the proposed ambient and service conditions.
2. Materials must be suiTable for the proposed application and have been approved by the Society.
3. The manufacture, processing and testing of materials must proceed in accordance with approved standards or to approved manufacturer's specification which have been examined by the Society.
4. Materials for fixed buoyancy elements must be suiTable for the proposed pressure and temperature ranges and have a low water-absorption factor.
5. Tethers are to be manufactured and tested in accordance with an approved standard or to approved manufacturer's specification which have been examined by the Society.
6. To the extent that this is necessary to the operation of the ROV and adequate protection by other means is not possible, materials must be resistant to the effect of the ambient media. In addition, materials must be mutually compatible.
7. SuiTable proof, e.g. a manufacturer's certificate is to be provided testifying to the characteristics of materials used for parts subject to approval.
604. Pressure Vessels
1. Pressure vessels and pressurized gas containers are subject to the requirements stated in the Rules of this Society or other equivalent.
2. Acrylic plastic viewports(or windows) are to be designed and manufactured in accordance with Pt 1, Ch 5, Sec 3.
605. Supporting Structure, Garage Design
1. The frame and supporting structure of ROV's, including the garages (where these exist), are to be designed and constructed in accordance with approved codes of practice.
2. Approved methods of calculation are to be applied to the design of the supporting structure com- ponents and the garage construction. The structures are to be dimensioned in such a way that at the anticipated loads the effective stress does not exceed 60 % of the yield strength.
3. The lifting attachment of the ROV is to be so designed and arranged that the ROV can be launched and recovered under the maximum permissible sea state conditions.
606. Piping, Valves, Fittings, Hoses and Umbilicals.
1. Pipes are to be designed and installed according to approved standards.
2. Pipes which are liable to be subjected in service to pressures higher than the designed pressure must be provided with a pressure-relief valve, safeguarding against dangerous blow offs.
3. Shutoff valves must conform to an approved standard. Valves with screw-down valve caps or spin- dles are to be safeguard against the unintended loosing of the cap.
30 Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
4. Hand-operated shutoff valves are
to be closed by clockwise rotation. The closed and open position
of functionally important shutoff valves must be clearly indicated. If they have to be handled by
divers in water they have to be constructed such that they can be easily operated by divers wear- ing diving gloves.
5. Hose fittings are to be made of corrosion resistant material and are to be designed to prevent unin- tentional release.
6. Hose lines, including their components, must be demonstrably suiTable for the proposed operating fluids, pressures and temperatures. Only types approved by the Society should be used.
7. Hose lines for liquids/gases are to be so designed that the bursting pressure is equivalent to at least 4 and 5 times respectively the maximum working pressure.
8. Hoses are to be fasted to their connectors by non-detachable hose couplings.
9. Where hoses are fitted with wire-mesh inlays which are not resistant to corrosion, the mesh is to be protected from water.
10. Umbilical hose lines must be provided with strain-relief devices unless they are provided with tethers.
11. Umbilicals must be protected against abrasion and damage. Where protective sheathing is used, care is to be taken to ensure that internal pressure does not build up in the event of minor hose leakages. Metal inlays in the protective sheathing are to be avoided.
12. Electrical cables in the umbilical must meet the requirement of the Rules.
607. Devices for Controlling/Adjusting Depth, Trim and Positive/Negative Buoyancy.
1. ROV's are to be equipped with devices for controlling/adjusting the depth and positive/negative buoyancy. It is necessary to ensure that theses devices are effective under all the specified con- dition of heeling and trim.
2. Depending on the type of ROV, the following may be regarded as devices for controlling the depth, trim and positive/negative buoyancy.
(1) fixed or changeable ballast and trimming weights in combination with the tether or launch and recovery system.
(2) fixed buoyancy elements, e.g. of pressure resistant foam.
(3) floodable ballast and trimming tanks
(4) propeller drives
3. The control devices must be capable of compensating for the expected differences in water density and of ensuring that the ROV attains a defined diving state.
4. Remote-operated device for controlling depth, trim and positive/negative buoyancy must be capable of being operated from ROV dive control console. In addition, the console shall in these cases pro- vide a continuous indication of the depth of the ROV.
608. Propulsion and Maneuvering Equipment
1. With regard to their type, number, size and arrangement, propulsion devices shall be designed to meet the requirements arising from the proposed application of the ROV.
2. Externally located propulsion unit shall be pressure-balanced or designed for the ROV's maximum diving pressure.
3. Propulsion plants of ROV's are to be designed for intermittent and continuous operation.
4. Electric propulsion motors are to be designed in accordance with the requirements of the Rules
5. Shaft penetrations through the walls of pressure vessels are to be provided with a proven shaft seal designed for the maximum diving depth.
6. Propellers are to be so arranged that the danger of unintentionally trapping the ROV or fouling umbilical or tether is largely eliminated.
7. Devices for controlling the speed and/or the direction of rotation are to be so designed that
the the
Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015 31
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
propulsion motor can be stopped in the event of their failure.
8. The operating condition of the propulsion units(thrust and direction of thrust and/or speed and di- rection of rotation) must be displayed at the ROV dive control station.
9. ROVs are to fitted with suiTable equipment giving the ROV the necessary maneuverability.
609.
Clamping and positioning Devices
1. Clamping devices are to be so designed and constructed that they can be set to a specified holding
power. In addition, be released in case
2. Positioning devices positioning devices
means are to be provided to enable the holding claw or similar mechanism to of a power failure.
are to be fitted with suitable siting/locating sensors. The controllability of the must be geared to the function of the ROV.
610. Working Appliances
1. Working appliances are to be mounted on the ROV in such a way that the danger of unintention- ally trapping the ROV or fouling the umbilical or tether is largely eliminated.
2. Tools which can be changed by remote control are to be provided with means for preventing the entry of seawater into the supply system.
3. Tools capable of rotating through 360° are to be so designed that any power, supply or control connection cannot be twisted off.
611. Electrical Equipment
1. All electrical equipment is to be so designed and installed that der the design conditions specified for the ROV.
2. Systems for which even a brief failure cannot be tolerated are terruptible power supply.
it is operational and serviceable un- to have battery support or an unin-
3. Where batteries are used, Pt 6 of Rules for the Classification of Steel Ship are to be observed for the battery systems. Battery chargers must have a characteristic conforming to the battery manu- facturer's recommendations.
4. The supply to the control station for the ROV shall be ensured by two mutually independent cir- cuits with changeover facility. Alternatively a direct supply may be routed from the emergency switchboard of the supply ship or the power supply station. Where ROV's operate with dive sup- port, electrical systems whose failure could endanger the divers are to be designed for high-avail- ability, e.g. with battery back-up.
5. Devices are to be provided enabling the ROV to be de-energized during launching and recovery.
6. approved supply systems are :
(1) direct current and single-phase alternating current, with both conductors insulated from the hull of the submersible.
(2) three-phase alternating current with the three conducts insulated from the hull of the submersible.
Networks with an earthed neutral are not permitted.
7. The permissible voltage and frequency deviation stated in Pt 6 of Rules for the Classification of Steel Ship shall not be exceeded.
8. A power-balance shall be prepared to prove that the rating of the main power supply is sufficient.
9. Appropriate diversity factors may be assumed for consumers which are intermittently connected.
10. A power margin is to be provided for transient peak loads (e.g. on motor start-up)
11. The emergency power supply is to be so designed that, if the main power supply fails, the ROV can be placed in a stationary operating condition which at no times prevents a danger. From this stationary condition it must be possible either to recover the ROV safety or to continue its task af- ter the main power supply has been restored.
32 Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
12. Electrical distribution systems are to be so designed that a fault not impair the operation of other circuits.
or failure in one circuit does
13. In normal operation the emergency power distribution system may be fed via an interconnector feeder from the main power-distribution systems.
14. The lengths of cable from storage batteries to the switchboard are to be kept as short as possible.
These cables are to be laid separately to the specially protected against mechanical damage.
15. In switchgear, measures are to be taken for the prevention of parasitic voltage. Safety-voltage cir- cuits shall not be run in the same conductor bundle as higher-voltage circuits or in the same cable duct. Terminals for different voltage levels are to be arranged separatedly and marked accordingly.
16. Each circuit is to be protected against short-circuit and overload.
17. All consumer circuits are to be designed for all-pole switching
18. Where ROV's operate with diver support, a continuous insulation-monitoring system is to be pro- vided which actuates a visual and audible alarm at the ROV control station when the value drops below a minimum level. Where the possibility of danger to humans cannot be ruled out, provision is to be made for the automatic disconnection of the circuit concerned.
19. ROV's with electrical equipment are to be provided with an earthing and equipotential system. All non-current-carrying metal parts are to be connected to this. Where earthing is not via the fasten- ings, protective conductors are to be fitted. Where protective conductors are used, the following points are to be observed :
(1) The protective conductor must take the form of an additional cable, and additional line or an additional core in the power cable. Cable sheaths or armouring shall not be used as protective conductors but are to be connected to the protective conductors.
(2) A conductor which carries current in normal operation shall not simultaneously be used as a protective conductor and shall not be connected jointly with the latter to the hull of the ROV.
(3) The cross-section of the protective conductor must be must be equivalent to at least half the
cross-section of the main conductor. However, with cross-section of up to 16 ŶŶË the cross-sec- tion must be the same as that of the main conductor. With separately laid protective conductors the minimum cross-section is 4 mmË.
In the propulsion system, the rating of the protective conductors is to be based on the max- ivmicuems apnodssaiblme asxhiomrtu-mcircteumit pceurarrteunrets roisfethoef ethqeuipmroetenctticvoencceorndeudctoorf otfhe90℃av.ailable protective de-
(4) Machine and equipment mounted on insulated vibration dampers are to be earthed via mobile cables, lines or copper braids.
(5) Protective conductors must be connected to the hull of the ROV at points which can easily be checked.
(6) In an easily accessible position on the superstructure and on the hull of the ROV a connecting
plate with M12 stud bolts is to be provided to which, e.g. on the supply ship, a protective con- ductor can be connected without the use of tools.
20. IP44 type protection is stipulated as a minimum requirement for the electrical equipment in ROV's. IP23 is sufficient for the devices incorporated in the ROV control station
21. The housings of non - pressure - compensated electrical equipment for underwater use are to be designed for the test diving-depth as a minimum requirement.
22. Umbilicals, underwater cables and lines must be impervious to transverse water penetration (i.e. no water shall penetrate the sheath) and are to be designed for the test diving depth as a minimum requirement.
23. Drum cables are to be so designed that mechanical forces are not transmitted by electrical components.
24. Penetration and plug-and-socket connections are to be designed and tested in accordance with Pt
6 of Rules for the Classification of Steel Ships.
25. Insulation classes A and E are not permissible for the windings of electrical machines.
612. Automation, Navigation and Locating Equipment
Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015 33
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
1. All devices for automatically monitoring and controlling the operating parameters of a ROV are to be so designed and constructed that they function properly under the design and ambient conditions laid down for the Vehicle.
2. Computer-aided operational control systems for navigating and/or monitoring and controlling the ROV are permissible.
Details of the scope and redundancy of the equipment and the extent and nature of the tests are to be agreed with the Society.
3. All monitoring and control devices are to be clearly inscribed and identified.
4. Indicating instruments and synoptic displays are to be designed and inscribed in such a way as to facilitate clear and rapid readings.
5. No fault or failure whatsoever in the automation system shall lead to an uncontrollable operating condition.
6. Automation equipment shall as far as possible be protected against incorrect operation.
7. Automation equipment must be capable of maintaining the operating parameters specified for the ROV.
8. All inadmissible deviations from the operating parameters must automatically actuate a (visual and audible) alarm at the ROV dive control station. The same applies to automatic changeovers in the supply system and to faults in the control and monitoring system.
9. In addition to electronic control and monitoring devices, independent safety devices must be pro- vided which prevent a fault in a system from creating an unsafe or undesirable operating condition.
10. Automatically operating monitoring and control devices must be capable of being switched to manual operation at any time. Exception to this rule are to agreed with the Society.
11. The thresholds of automation devices are to be co-ordinated in such a way that, when a limit value is reached, an indicating signal is actuated followed by the response of the safety devices on the expiry of a specific warning period or on the further variation of the process variable at a pre- set speed.
12. The overall behaviour of the automation equipment must be compatible with the time constants of the devices and components in the system.
13. The criterion for the noise immunity of electronic systems is in accordance with the Rule of
Guidance for Approval of Manufacturing Process and Type Approval, Etc.
14. Electronic automation equipment shall comprise easily interchangeable modules using the plug-in system wherever possible.
The modules should be largely standardized, and the number of module types should be kept small to reduce the spares inventory.
15. Plug-in cards must be clearly marked or coded as a safeguard against accidental confusion.
16. Measures must be taken to prevent condensation inside electronic switched off.
17. Wherever possible, automation equipment should be operable without ation of any cooling system is to be monitored.
18. Components must be effectively fastened. The mechanical loading nection by vibration and shuddering is to be minimized.
equipment even when it is forced ventilation. The oper- of wires and soldered con-
19. The construction of systems and equipment should be simple and straightforward. Easy accessi- bility for measurements and repairs is desirable.
20. Signalling and open and closed-loop control devices for safety-related functions must be con- structed on the fail-safe principle. I.e. defects such as short-circuit, earth faults and breaks cannot produce conditions endangering humans or equipment. This is to be based on the assumption of signal faults.
The failure of one module, e.g. due to short-circuit, shall not result in damage to other modules.
34 Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
21. In programmable controllers the electrical values of the sensors shall meet the safety requirements for control devices. This means primarily:
(1) H-level start up, i.e. by energization via NO contacts.
(2) L-level shutdown, i.e. by de-energization via NC contacts.
22. Control devices for safety function, e.g. emergency-stop sensors, are to be independent of a pro- grammable controller and are to act directly on the output device, e.g. stop solenoid valve. They are to be safeguarded against unintentional operation.
23. Programmable controllers should be non- interesting and in case of fault should not cause dis-
turbances in program-independent safety interlocks and safety switching sequences for subroutines.
24. Freely accessible potentiometers and other components provided for adjustment or working setting must be capable of being locked in the operating position.
25. Switchgear interfaces must be so designed that contact chatter has no adverse effects on the ation of the equipment.
fixed point oper-
26. Printed conductors forming part of circuits extending outside the enclose containing the printed circuit boards must be conditionally short-circuit-proof, i.e. in the event of an external short circuit only the protective devices provided may respond without destroying the printed conductors.
27. The equipment shall not be damaged by brief voltage surges in the ship's power supply which may be caused by switching operations. The design shall allow for overvoltages amounting to ap- proximately twice the rated voltage and lasting 1 ms.
Where equipment is supplied from static converters, allowance is to be made for periodic voltage pulses lasting about 0.5 ms. The amplitude depends on the type of converter and must be inves- tigated in each case.
28. Power supply units for automation equipment must at least have short-circuit and overload protection.
29. The reference-conductor system is to be so designed that breaks are as far as possible eliminated.
This is achieved, for voltage and frequency deviations mentioned in accordance with the Rules.
30. Automation equipment must be capable of reliable operation with the voltage and frequency devia- tions mentioned in the Rules Pt 2, Sec 10 of Guidance for Approval of Manufacturing Process and Type Approval, Etc.
31. For monitoring and controlling the ROV a control station or console is to be provided at which all the important data relating to the vehicle are displayed and all the controls and monitors, in- cluding TV and communications facilitates, are located which are needed for the operation of the ROV.
32.The control station instruments for supervision, controlling and operating the grouped and arranged on ergonomic principles.
33.As far as feasible and rational, initiated control functions are to be indicated by on the console or switchboard, as applicable.
34.All sensors for registering the ambient and operating conditions of ROV's type-testes by the Society.
ROV are to be synoptic displays shall have been
35.All the electronically operated navigation and locating equipment necessary to the safety of the ROV's is to be connected to the vehicle's emergency power supply. Its operational or stand-by sta- tus must be clearly indicated as the control station.
36.As far as is feasible and rational, ROV's should be equipped with an automatic emergency locat- ing device (pinger).
37.The fitting of the ROV's with navigation and locating equipment shall comply with any official regulations applicable in the home country.
Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015 35
Pt 2 Underwater Equipments
Ch 1 Remote-Operated Vehicles (ROVs) Pt 2, Ch 1
613.
ROVs control station
1. ROVs control station should be located at a place where the operator generally is able to know the operation condition of all the system of ROV's and apparatus but not installed within dangerous area.
2. Piping system is to be designed as far as possible from the maneuvering apparatus.
3. The ROVs control station is to be separated from other spaces by bulkheads and decks of type A- 0 class.
4. The fire extinguishing system is to be designed and constructed in such a way that it should not cause the equipment and the maneuvering to be disorder against fire wherever possible.
5. Alarm devises should be appropriately audible and viable in/outside dive control station.
6. Indicators / alarm devices signed from depth, remained battery capacity, operating condition of launch and recovery system and other functions with hazardous elements should be connected to an independent supply sources. Emergency stop devices are also to be independent of others.
7. Direct communication system should be equipped such a way that it is to be capable of connecting among the following positions
(1) dive control station
(2) other control room on a support ship
(3) maneuvering station of launch and recovery system
(4) remote-control position of ROV's.
614. Launch and Recovery system
1. The requirements of Lunch and Recovery system are to be complied with Pt 9, Ch 7, Sec 14 of
Rules for the Classification of Steel Ships.
2. In addition the followings are to be complied with :
(1) Unless other wise specified in the followings, the mechanical equipment of launch and recovery system for lifting gear is to be confirmed to Pt 9 of Rules for the Classification of Steel Ships.
(2) The launch and recovery system must be capable of effecting the safe launch and recovery of the ROV under the ambient conditions-mentioned. Where necessary, it is to be fitted with de- vices for reducing the dynamic loads.
(3) All interchangeable parts such as blocks, hook, shackle etc, must conform to approved standards and be designed for twice the working load.
(4) The maximum static tensile stress on steel cables due to the working load shall not exceed 1/8 of the proved rupture strength. Where cables of natural or synthetic fibers are used, the max-
imum static stress due to the working load shall not exceed 1/10 of the proved rupture strength.
(5) The launch and recovery system is to be designed for a defined working load based on the weight of the ROV including its equipment and ballast weight. Without more accurate evidence,
seaway effects may be allowed for by increasing the relevant working load purpose of calculation and dimensioning and assuming that it can act at an vertical in any direction.
(6) Launch and recovery systems are to be equipped to prevent excessive twisting ing recovery. 
by 50 % for the angle of 12° off
of the ROV dur-
36 Guidance Relating to the Rules for the Classification of Underwater Vehicles 2015