Section 7 Machinery

7.1.1 The requirements of Ch 9 Machinery of the Code for Lifting Appliances in a Marine Environment, July 2022 are, in general, applicable to machinery items of OPTS unless otherwise stated in this Section. Proposals to deviate from these requirements will be specially considered.

7.1.2 Any single point failure of any machinery component and equipment shall not result in uncontrolled motions of the OPTS. See also Ch 1, 8.16 Redundancy of components.

7.1.3 Materials for machinery items are to be in compliance with Ch 9, 2.2 Materials of the Code for Lifting Appliances in a Marine Environment, July 2022.

7.1.4 Fatigue calculations of machinery items are to be carried out in accordance with a recognised National or International Standard (e.g. EN 13001 Cranes – General design, ISO 6336 Calculation of load capacity of spur and helical gears). Other standards will be specially considered. The applied standard shall be agreed with LR.

7.1.5 Testing of machinery is to be carried out as per the requirements of Ch 1, 13.1 Testing.

7.2.1 Winches and their components are to be in compliance with Ch 9, 3 Mechanical design requirements and Ch 9, 4 Machinery engaged in handling of personnel of the Code for Lifting Appliances in a Marine Environment, July 2022.

7.3.1 Gears and gearboxes are to be in compliance with Ch 9, 3 Mechanical design requirements and Ch 9, 4 Machinery engaged in handling of personnel of the Code for Lifting Appliances in a Marine Environment.

7.4.1 Linear actuators shall be designed in compliance with Ch 4 Cranes and Submersible Lifting Appliances, Ch 9 Machinery and Ch 10 Electrotechnical Systems of the Code for Lifting Appliances in a Marine Environment, July 2022 (as applicable) or a recognised National or International Standard.

7.4.2 Linear actuators are, in the following, to be understood as hydraulically, pneumatically or electrically driven actuators, either by internal pressure or rotating motors.

7.4.3 Linear actuators, which contain a lead screw to arrange for axial movement of the rod, are to be considered for buckling both on the entire extended actuator and the lead screw part only.

7.4.4 Linear actuators are to be fitted with end stops sufficient to withstand the kinetic energy from both the moving and rotating parts as applicable.

7.4.5 Lead screws with bronze or plastic nuts are to have a facility to protect the load from being dropped due to excessive wear of the bronze or plastic nut and/or the lead screw and are to have an arrangement to lubricate the lead screw and the nut.

7.4.6 Linear actuators which are fitted on deck are to be sufficiently protected from environmental effects such as green sea.

7.4.7 Linear actuators shall not be subjected to loads other than axial forces, i.e. external bending moments. Other proposals will be specially considered.

7.4.8 Hydraulic cylinders are to be designed to comply with Ch 9, 5 Hydraulic cylinders of the Code for Lifting Appliances in a Marine Environment, July 2022. Possible steel to steel contacts between any of the hydraulic cylinder components need to be taken into consideration.

7.5.1 Mounting of the piping and the equipment shall be performed in such a way as to allow inspection along its length.

7.5.2 For motion compensated systems directly operated by hydraulic cylinders or where hydraulic cylinders are otherwise engaged in the support or transfer of persons, valves shall be fitted to prevent uncontrolled motions in case of pipe or hose failure. The system shall be designed such that, in the event of hydraulic leakage, no dangerous situation can occur.

7.5.3 The arrangements for storage, distribution and utilisation of hydraulic and flammable oils employed under pressure in power transmission systems, control and actuating systems, and hydraulic media in systems are to comply with the requirements of this Section.

7.5.4 Hydraulic power units (HPU) are to deliver hydraulic fluid under pressure for actuation of hydraulically driven machinery and for operation of remote-controlled equipment.

7.5.5 Hydraulic fluids are to be suitable for the intended purpose under all operating service conditions.

7.5.6 The hydraulic system shall be provided with arrangements to maintain the cleanliness of the hydraulic fluid taking into consideration the type and design of the hydraulic system.

7.5.7 Materials used for all parts of hydraulic seals are to be compatible with the working fluid at the appropriate working temperature and pressure.

7.5.8 The OPTS hydraulic power actuating systems shall be independent of the ship’s hydraulic systems.

7.5.9 Piping shall be supported so that undue stresses are eliminated. Particular attention shall be paid to joints, bends and fittings, and at any section of the system subject to vibration. Protection is to be provided at locations of enhanced risk of external impact.

7.5.10 Pressure hoses shall be able to withstand four times the maximum design pressure. Hydraulic hoses shall be suitable for the type of hydraulic fluid used in the system.

7.5.11 Hoses shall be installed so as to prevent sharp bends and chafing or trapping due to moving parts of the machine.

7.5.12 The manufacturer shall specify the intervals at which the hoses should be replaced.

7.5.13 Supply piping to hydraulic power actuating systems are to be as short as practicable.

7.5.14 The use of flexible hoses is to be restricted to positions where it is necessary to accommodate relative movement between items of equipment and fixed pipe-work.

7.5.15 Where a hydraulic securing is applied, the system is to be capable of being mechanically locked in the closed position so that, in the event of hydraulic system failure, the securing arrangements will remain locked.

7.6.1 Tanks and reservoirs for service and the storage of hydraulic fluids are to be made of steel and suitable for the maximum head of fluid to which the tanks may be subjected. In general, tanks are to have a minimum plate thickness of 5 mm, but in the case of very small tanks, the minimum thickness may be 3 mm.

7.6.2 The storage capacity for hydraulic fluids is to be sufficient to recharge the largest system on board plus normal usage during a typical mission. Storage capacity is to be sufficient for each type of hydraulic fluid used. Storage capability sufficient to handle the full capacity of the largest hydraulic system on board is also to be provided for contaminated hydraulic fluids.

7.6.3 Tanks and reservoirs are to be provided with two connections at diagonally opposite corners, one top and one bottom, to permit the contents to be circulated through portable flushing equipment.

7.6.4 The capacity of hydraulic fluid reservoirs at normal working level is to ensure a residence time for the fluid of not less than 3 minutes.

7.6.5 A vertical baffle plate is to be fitted dividing each reservoir into two compartments interconnected at the top of the baffle. Return fluid, drains, etc. are to be made to one side of the baffle whilst pump suctions are to be taken from the other side.

7.6.6 All tanks and reservoirs are to be provided with approved means of hydraulic fluid level indication.

7.6.7 Tanks which are required to provide heat dissipation from the hydraulic system shall be provided with temperature indication.

7.6.8 All tanks and reservoirs are to be provided with approved means of sampling the contents and a means of access for cleaning.

7.6.9 All tanks are to be fitted with a deaeration capacity of not less than 125 per cent of all the power pumps connected which may run simultaneously.

7.6.10 All tanks are to be designed such that all pump suctions remain below the lowest set oil level for all design trim and conditions.

7.7.1 Two or more hydraulic pumps are to be provided for each power actuating system. Each pump is to be of sufficient capacity to supply the system under defined operational requirements stated in the system design description.

7.7.2 All hydraulic pumps are to be provided with relief valves. Each relief valve is to be in a closed circuit, i.e. arranged to discharge back to the suction side of the pump and effectively to limit the pump discharge pressure to the design pressure of the system. The relief valve set pressure is to be not less than 125 per cent of the maximum anticipated working pressure to prevent loss of movement/functionality during discharging.

7.7.3 Where pump units are provided with accumulators, a shut-off valve is to be provided between the pressure line and the accumulator with a bleed valve fitted between the shut-off valve and the accumulator.

7.7.4 Where accumulators are provided with gas pressurisation, isolating valves are to be fitted in the gas lines at each accumulator. A relief valve is to be fitted in the gas supply line to prevent the gas supply line and the accumulator being pressurised above its maximum working pressure.

7.8.1 Cooling arrangements for hydraulic fluids are to be provided where the operating temperature of the fluid may exceed the maximum design temperature limitations of the fluid or equipment in the system as defined in the system design description.

7.8.2 Where the provision of cooling arrangements is necessary to maintain hydraulic fluid temperatures, not less than two means of cooling are to be provided and configured such as to provide cooling with one means out of action.

7.9.1 Piping systems for flammable hydraulic fluids are to be installed to avoid fluid spray or leakage onto hot surfaces, into machinery air intakes, or onto other sources of ignition such as electrical equipment. Pipe joints are to be kept to a minimum, and where provided are to be of a type, acceptable to LR. Pipes are to be led in well lit and readily visible positions.

7.9.2 Pipes conveying hydraulic oil under pressure are to be of seamless steel or other approved material having flanged or welded joints and are to be placed in clearly visible and readily accessible locations. The number of flanged joints is to be kept to a minimum.

7.9.3 The design of filter and strainer arrangements is to be such as to avoid the possibility of them being opened inadvertently when under pressure. This may be achieved either by mechanically preventing the pressurised filter from being opened or by providing pressure gauges which clearly indicate which filter is under pressure. In either case, suitable means for pressure release are to be provided, with drain pipes led to a safe location.

7.9.4 Pressure equipment, such as pressure vessels, bladder accumulators and nitrogen bottles, is to comply with Pt 5, Ch 11 Other Pressure Vessels of the Rules and Regulations for the Classification of Ships, July 2022.

7.9.5 Pressure piping systems are to be in compliance with Pt 5, Ch 12 Piping Design Requirements of the Rules and Regulations for the Classification of Ships, July 2022.

7.10.1 Bearings are to be in compliance with Ch 9, 3.10 Bearings of the Code for Lifting Appliances in a Marine Environment, July 2022.

7.10.2  Slewing rings are to be in compliance with Ch 4, 3.7 Slew rings and Ch 9, 3.11 Slewing rings of the Code for Lifting Appliances in a Marine Environment, July 2022.

7.11.1 If the design of the OPTS requires a rope reeving system, the requirements in this Section shall be complied with.

7.11.2 The sheaves shall be designed to comply with Ch 8, 3.3 Materials and construction of the Code for Lifting Appliances in a Marine Environment, July 2022. If the reeving system is involved in the motion compensation, then the diameter of the sheave will be specially considered.

7.11.3 The friction effects in the reeving system need to be taken into account, see Ch 4, 2.26 Rope safety factors and sheave ratio 2.26.4 of the Code for Lifting Appliances in a Marine Environment, July 2022.

7.11.4 The reeving system requires a slack rope detection and prevention system.

7.11.5 The reeving system is to be designed with due consideration of the effects of fatigue on the wire rope (e.g. avoidance of reverse bends).

7.12.1 Brakes are to be in compliance with the applicable requirements of Ch 9, 3 Mechanical design requirements and Ch 9, 4 Machinery engaged in handling of personnel of the Code for Lifting Appliances in a Marine Environment, July 2022.

7.12.2 Any deviation from the application of the requirements for brakes (as outlined in Ch 1, 7.12 Brakes 7.12.1) for ST-P, ST-A and ST-H system types will be specially considered.

7.13.1 Passive and active OPTS (ST-P, ST-A and ST-H) are to be provided with mechanical limiting devices which prevent exceeding the geometrical limits of all moving components and motions of the OTPS. A minimum of the following mechanical limits shall be foreseen in the design:

1. telescoping system;
2. luffing system;
3. slewing system, in case the slewing angle is required to be limited;
4. hydraulic cylinders; and
5. electro-mechanical actuators.

7.13.2 The arrival at the mechanical limits shall not result in a dangerous situation for the transferring personnel, the OPTS, the mothership or the target unit/structure.

7.13.3 The mechanical limiting devices are to be designed to withstand the maximum forces resulting from a single point failure.

7.13.4 The telescoping and luffing motion shall also be limited by a mechanical end stop in addition to the limit switches.

7.13.5 In case the slewing motion is required to be limited, a mechanical end stop shall be provided in addition to the limit switches.