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What is AiP?

AiP, which stands for Approval in Principle, is a scheme for the examination of plans and documents based on the rules for products in the early design stage to confirm their technical feasibility from the viewpoint of the rules.

The AiP is generally applied to technologies that are newly developed or have little experince in the maritime industry. The product concepts, including but not limited to the following examples, may be subject to an AiP.

Examples of ships

• Ships using alternative fuels (LNG, LPG, methanol, ammonia, hydrogen, etc.)
• Ships carrying special liquefied gases (liquefied hydrogen, liquefied CO2, etc.)
• Automated/autonomous ships
• Offshore floating facilities (FPSO, FLNG, FSRU, offshore plants, etc.)

Examples of equipment and systems

• Liquefied gas cargo/fuel containment systems
• Wind assisted propulsion systems
• Fuel supply systems
• Gas reforming systems

Approval Framework

As the AiP does not certify complete conformity to rules, its framework is decided upon consultation with reference to the provisions of relevant rules, taking into consideration the design stage of the concerned product and the applicant's requirements. The framework for the AiP is generally determined by the following procedure.

(1) Confirmation of the product specifications

(2) Determination of referenced rules

(3) Determination of the scope of approval

Required Documents

The documents that need to be checked in the AiP scheme are determined according to the approval framework agreed upon with the applicant. The required documents will vary according to the details of the agreement, but in general, they should include the following.

(1) Documents pertaining to product specifications

(2) Documents pertaining to technical validation of the product

(3) Documents pertaining to risk assessment

For reference, specific examples of the documents required for the AiP are shown below, using several products as examples.

Table 1 Examples of basic design approval documents for alternative fuelled ships

1	Basic specifications for the vessel
2	Basic specifications for alternative fuel related equipment
3	General arrangement drawings
4	Engine room layout diagram
5	Alternative fuel piping system diagram
6	Hazardous location identification diagram
7	Ventilation system diagram
8	Fire extinguishing and fire protection system diagram
9	Longitudinal strength and non-damage restoration calculations
10	Documents relating to risk assessment

Table 2 Examples of basic design approval documents for battery propelled ships

1	Basic specifications for ship
2	Basic specifications for battery equipment
3	Basic specifications for energy management system
4	General arrangement drawings
5	Engine room layout drawings
6	Battery room layout diagram
7	Power system diagram
8	Hazardous location identification diagram
9	Fire extinguishing and fire protection equipment diagram
10	Longitudinal strength and non-damage restoration calculations
11	Documents for risk assessment

Table 3 Examples of basic design approval documents for offshore floating facilities

1	Basic specifications for floating facilities
2	General arrangement drawing
3	Central cross-sectional drawing
4	Structural analysis method for hull and mooring equipment
5	Longitudinal strength and non-damage restoration calculations
6	Basic design clauses for topside equipment
7	Equipment list for topside facilities
8	Process flow diagram for topside equipment
9	Hazardous location identification diagram
10	Fire fighting and fire protection equipment diagram
11	Normal and emergency operating concept
12	Documents for risk assessment

Table 4 Examples of basic design approval documents for wind propulsion equipment

1	Basic specifications of the equipment
2	Overall assembly drawing
3	Detailed structural drawing
4	Structural analysis method (including trial analysis results for typical loading conditions)
5	Drive unit structural drawing
6	Power system diagram
7	Normal and emergency operating concept
8	Material for risk assessment (including discussion of effects on the vessel)

For other details on the AiP scheme, see Guidelines for Basic Design Approval and General Design Approval (Edition 1.0). The Guidelines can be downloaded from “ClassNK MyPage” after the registration.

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Trends of AiP and approval records

LNG/LPG/methanol fuelled ships

For alternative fuels, such as LNG/LPG/methanol fuels, where the ships fuelled with them have already been in service, the development from basic design to detailed design has progressed relatively smoothly, and design approval is often granted without going through the stage of obtaining an AiP as an implementation project. For methanol fuels, designs are planned not only for methanol carriers using methanol cargo as fuel but also for methanol fuelled bulk carriers and container ships.

Ammonia-fuelled ship

In parallel with the ongoing development of ammonia-fuelled engines, systems for supplying ammonia fuel to engines and the design of ships equipped with these engines and systems are underway. Ammonia is highly toxic and corrosive, so in order to confirm the feasibility from the initial design stage, an AiP is issued based on the Society's Guidelines for Alternative Fuelled Ships (methanol/ethanol/LPG/ammonia) after checking safe handling on board and identifying issues to be considered in the detailed design. We also issue AiP for 'Ammonia Fuel Ready' for ships using conventional fuels, in which a conceptual design is prepared in advance in anticipation of future conversion to ammonia fuels for zero-emission ships.

Hydrogen-fuelled ships and fuel-cell-powered ships

The use of hydrogen fuel has already been realized in small coastal vessels equipped with fuel cells. Hydrogen-fuelled engines are also being developed for the future use of decarbonized fuels in larger ships. Due to the physical properties of hydrogen, safety measures are required, particularly against hydrogen embrittlement of materials, leakage, and fire. In addition, when hydrogen is liquefied for use on board to store large quantities of fuel, safety measures are also required to ensure the resistance of materials to cryogenic temperatures of -253°C and to the liquefaction of the surrounding air (nitrogen, oxygen, etc.). As the development of hydrogen-fuelled engines progresses, applications of AiP certification are expected to increase in order to confirm the feasibility of ships equipped with hydrogen-fuelled engines.

CO2 carriers and Carbon Capture

Projects for marine transportation of CO2 captured from onshore power plants and other sources are gaining momentum, and the number of AiPs issued for liquefied CO2 carriers is increasing accordingly. A system has also been developed to capture CO2 emitted from ships on board, based on land-based CO2 capture technology. In the future, we expect to see an increase in the application of AiP to confirm the feasibility of ships equipped with liquefaction and storage systems on board, in addition to the CO2 capture system.

Wind-assisted propulsion ship

As one of the technologies for reducing GHG emissions, devices have been developed and are already being put into practical use to assist ship propulsion by utilizing the power of wind, a renewable energy source. Rigid sails, kites, rotor sails, and other systems have been developed for these wind-assisted propulsion systems, and AiPs have been issued for ships equipped with these systems on deck after confirming their feasibility based on the Society's 'Guidelines for Wind-assisted Propulsion Systems for Ships.' Ships combining the use of the above-mentioned alternative fuels with wind-assisted propulsion systems are also being planned.