Plastic pipes in shipbuilding: Lightweight, corrosion-resistant, sustainable __

Kunststoffrohre im Schiffbau: leicht, korrosionsresistent, nachhaltig
27. May 2024 7 min.

How can the modern shipbuilding industry meet the increasing challenges of weight, corrosion, and environmental sustainability? Why are more and more shipyards relying on plastic instead of traditional metal pipe systems? The answers lie in the unique properties and advantages of plastic pipes, which make them the ideal choice for numerous marine applications. aquatherm plastic pipes set new standards in shipbuilding with their lightness, corrosion resistance and sustainability.

Advantages of plastic pipe systems in shipbuilding over metal pipes

The use of aquatherm plastic pipe systems in shipbuilding offers a number of decisive advantages over conventional metal pipes. These benefits not only improve the efficiency and safety of maritime structures, but also contribute to sustainability and cost-effectiveness. Ship owners and shipyards have recognised that plastic pipes significantly extend the life of onboard piping systems. Innovative plastics are resilient against the multitude of complex factors that pipe installations on ships are subjected to on the high seas.

Corrosion resistance

One of the biggest advantages of aquatherm plastic pipes is their natural resistance to corrosion. Unlike metal pipes, which can rust or corrode due to seawater and chemical exposure, plastic pipes are immune to such influences. This significantly extends their service life and reduces the need for frequent maintenance or quick replacement.

Low weight

Plastic pipes are significantly lighter than metal pipes. While steel has a nominal weight of 7,800 kg/m³, aquatherm pipes have only 980 kg/m³. This makes it easier to transport, handle and install on board. A lighter piping system also helps to reduce the overall weight of the vessel, which in turn improves fuel efficiency – an important aspect in terms of reducing operating costs and environmental impact.

Flexibility and adaptability

aquatherm plastic pipes offer greater flexibility, making them ideal for installation in complex and narrow ship designs. Their ability to bend slightly without breaking minimises the risk of cracking under pressure and vibration that ships are constantly exposed to.

Chemical resistance

The chemical composition of plastic pipes allows them to resist a wide range of chemical substances that could otherwise damage metal pipes. This is especially important in systems that work with aggressive liquids such as wastewater, chemically treated ballast water, or coolants.

Thermal and acoustic insulation

Plastic pipes provide natural insulation properties that help control temperature within the piping and minimise heat transfer. This is especially beneficial for heating, ventilation, and air conditioning (HVAC) systems. They are also more effective at reducing noise, resulting in a quieter and more pleasant environment on board.

Easy and quick installation

Thanks to aquatherm's easy handling and innovative connection system, plastic pipe systems can be installed faster and with less work than metal pipes. This saves time and costs during shipbuilding.


aquatherm plastic pipes are made of fusiolen® polypropylene, a recyclable and environmentally friendly material that does not release any harmful substances during production, use and disposal. To ensure sustainability in shipbuilding projects, aquatherm offers comprehensive certifications and EPD environmental declarations for its product portfolio.


Where plastic pipes are used in shipbuilding

aquatherm plastic pipes offer a wide range of applications in shipbuilding due to their robust, corrosion-resistant, and lightweight properties. These versatile systems can be found in almost all areas of a ship, from the vital supply systems to specialised areas of operation:

Potable water

Plastic pipes from aquatherm ensure a safe and hygienic distribution of drinking water on board, which is particularly important on large passenger ships such as cruise ships.

The safety and quality of potable water supply play a central role, especially on cruise ships, which often accommodate thousands of passengers. The aquatherm green piping system sets new standards here. This system is not only corrosion-resistant, but also tasteless and odourless, as well as physiologically and microbiologically harmless. With over 450 different pipe types and fittings available in dimensions from 20 to 355 mm, aquatherm green enables safe and easy installation, supported by the availability of prefabricated pipe assemblies.

Each ship must bunker its drinking water in selected ports in strict compliance with all relevant chemical and hygienic standards in order to avoid any health hazard to passengers during their time on the high seas. In this context, plastic pipe systems have proven to be particularly efficient, as they ensure a constant quality of the water even with varying water qualities such as different pH values and salt contents.

aquatherm plastic pipes are not only lighter than metal pipes, which reduces the overall load of the ship, but also resistant to humid and salty air, eliminating the problem of contact corrosion with the metal hull. In addition, they are insensitive to constant vibrations on board, prevent condensation from forming in warm and humid climates, and minimise flow noise in the pipes.

Plastic pipes for transporting wastewater in ships

They are insensitive to corrosion from wastewater and chemical influences, making them ideal for transporting wastewater within the ship. In particular, aquatherm blue pipelines are ideally suited for disposal systems due to their high chemical resistance to seawater and all types of wastewater. The smooth surfaces of plastic also deter solid components from adhering to wastewater much more effectively than metal pipes, thereby efficiently preventing blockages in ship wastewater systems.

Heating, ventilation, and air conditioning (HVAC) systems

aquatherm plastic pipes support efficient HVAC systems with their excellent thermal properties and low weight. 

On ships and offshore installations, an efficient heating, ventilation, and air conditioning (HVAC) system is essential for the comfort and safety of passengers and crew. The planning and design of the systems requires thorough consideration of various factors such as ship type, environmental aspects, and health and safety requirements to ensure optimal and trouble-free operation.

A crucial element of HVAC systems on ships involves the utilisation of cooling water units and absorption chillers, frequently interconnected with ventilation units in cabins and cooling systems for electronic equipment via an extensive network of long-distance lines. Traditionally, water or water-glycol mixtures have been used to transport energy within these systems to avoid the need for large refrigerant line systems. In special applications, even seawater can be used as a cost-efficient cooling medium, but this places special demands on the corrosion resistance of the materials used.

This is where the aquatherm blue pipe system offers the solution. These pipes, available in dimensions from 20 to 630 mm, meet the highest requirements under maritime conditions with their chemical resistance and durability. The service life of up to 100 years under sustainable operating conditions is outstanding.

Compared to traditional metal or GRP pipes (glass fibre reinforced plastic), aquatherm polypropylene pipes are significantly lighter. This simplifies installation and helps to reduce fuel consumption and costs by reducing the overall weight of the vessel.

Ballast water systems

In ballast water systems, aquatherm plastic pipes ensure efficient and safe handling of ballast water, which is crucial for the stability of the ship.

Ballast water systems are crucial for the safety and stability of ships. They play a central role in balancing the ship in changing cargo conditions and ensuring stability in different environmental conditions. Precise control and high reliability of the systems used are important here in order to regulate the lateral stability as well as the rolling and trimming behaviour of the ship. 

aquatherm's piping systems are ideal for transporting ballast water. They offer an efficient and safe solution due to their corrosion resistance and low friction coefficient. Ships must purify their ballast water of marine organisms to avoid negative impacts on new environments and to comply with international regulations. The aquatherm pipe systems support the entire cleaning process – from pre-treatment and filtration to disinfection – with their chemical resistance and structural integrity.

These properties are of fundamental importance, as traditional materials corrode very quickly and therefore endanger safety. The low weight of aquatherm systems also helps to optimise fuel efficiency.


Efficient processing of plastic pipes in shipbuilding and shipyards

aquatherm's plastic pipe systems also offer profitable advantages when processing in the confined spaces in shipyards and ships. Plastic pipes and fittings are first briefly heated with the help of specially developed tools and then joined together seamlessly. This process allows the plastic to fuse into a homogeneous and material-tight unit, ensuring maximum safety of the joints.

aquatherm offers an extensive range of processing tools for this purpose, ranging from simple manual equipment to high-precision CNC-controlled welding machines. While butt welding is mainly done in the workshop, flanges can be used for on-site connection. This saves time and costs.

For applications that require increased resistance to seawater, flanges are available in pressure class PN 10 and, on special request, also in PN 16. In addition, flange adapters are available both as a standard product and according to special customer requirements for butterfly valves. The seals are supplied in EPDM quality, which further supports the longevity and reliability of the systems.


Prefabrication of plastic pipe manifolds in shipbuilding

For today's variety of fluid distribution systems, standardised or modular concepts are often not sufficient. Every shipbuilding project has unique requirements that require individual solutions. aquatherm therefore offers customers tailor-made solutions by providing prefabricated manifolds and assemblies. These are specially tailored to the media types, the specific application, the ship's design conditions as well as relevant regulations and laws.

For shipbuilding, where complex and precise structures are required, aquatherm's prefabrication technology enables the production and delivery of ready-to-install systems to any location worldwide. The process begins with the submission of the required design data, including 3D drawings and sketches with exact measurements. aquatherm can process data from 3D scans, which enables precise and efficient production preparation.

After the data analysis, aquatherm provides a detailed offer that includes both a material extract and the corresponding drawings. This process is supported by a team of experienced technicians who provide ongoing advice and support to customers to ensure that each solution is optimally tailored to the specific requirements of each project.


Practical examples of aquatherm plastic pipes in shipbuilding


Hybrid superyacht Artefact

The hybrid superyacht Artefact, built by the German shipyard Nobiskrug, represents a turning point in luxury yacht building. With a length of 80 metres and a gross tonnage of 2,999, she is currently the world's highest-volume superyacht and one of the first to comply with the strict IMO Tier III emission standards. The Artefact integrates advanced technologies such as solar panels and a battery storage system, which make it possible to operate completely emission-free at times. aquatherm green was chosen for drinking water supply and wastewater recycling due to its corrosion resistance and excellent ecological properties.



Research Vessels "Snow Dragon 1 and 2"

The research vessels Snow Dragon 1 and Snow Dragon 2 are designed for Antarctic expeditions and are equipped with aquatherm green and aquatherm blue systems for drinking water and wastewater management. The systems were selected for their exceptional corrosion resistance and durability. They enable the ships to operate even in the most extreme conditions. The corrosion-free polypropylene material of aquatherm systems is ideal for use in cold and salty environments.

Ice Dragon


Dreding vessel in Curaçao

A specialised dredging vessel in Curaçao uses aquatherm blue for its ballast pipes to increase efficiency in the extraction and transport of water-sand mixtures. This application demonstrates the durability and reliability of aquatherm products under the demanding conditions of port operations.

The barge Arcalupa

The Italian barge Arcalupa has a dead weight of around 4,000 tons and can transport heavy loads of up to 14,000 tons. As a mobile dry dock, it can be completely flooded within about 10 hours. It transports ship hulls, cruise ships, concrete masts and extensive steel structures for the oil and gas industry. For its functions, aquatherm blue was used for the ballast water pipes and the tank ventilation of the 20 ballast tanks. aquatherm blue was chosen because of its excellent corrosion resistance and ability to withstand the extreme operating conditions in aggressive salt water.



The use of aquatherm plastic pipes in shipbuilding contributes to sustainable change and at the same time creates new economic perspectives. Combining lightness, corrosion resistance and efficient recyclability, the pipes offer a compelling alternative to traditional metal systems.

Their versatility, from drinking water supply to HVAC systems and ballast water applications, shows that they are much more than just an alternative: they are an innovation and an integral part of the future of shipbuilding.

The advantages of aquatherm pipe systems are manifold. The significant reduction in overall weight helps to reduce operating costs and minimise environmental impact. The chemical resistance and quick, easy installation of these systems reduce maintenance and extend the life of pipe installations.

The shipbuilding projects implemented so far underline that the choice of aquatherm not only offers technical and economic advantages, but also makes a significant contribution to the protection of the maritime environment.

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