CARGO TRANSFER SYSTEM: Paving the way for the transfer of larger cargos

In the very first edition of Offshore WIND we reported on access systems as the means for safe transfers of personnel to offshore wind turbines. At that time it was still a relatively new topic in this industry. We discussed the systems by Dutch company Ampelmann Operations B.V. and by Offshore Solutions.

Now, five years later, with 40 access systems in operation, and more being built, over 800,000 transfers at sea, and the recent acquisition of Offshore Solutions, Ampelmann Operations has positioned itself firmly in the global offshore energy industry in general, including, specifically, this industry. And still the company is continuously looking at further innovations.

Offshore WIND spoke once again to Jan van der Tempel, CEO and founder of Ampelmann Operations and creative brain behind the products. The company started in 2008 and their first access systems, which have in time become better known as the ‘Ampelmann’, were initially deployed in the oil & gas industry.

The Ampelmann is a motion compensated gangway that is based on a self-stabilising hexapod with 6 hydraulic cylinders that compensates the real time motions of a vessel therefore enabling a safe passage from a moving vessel to a fixed structure. There are currently 2 types available, the A-type with 2m cylinders which is designed for safe operation in significant wave heights (Hs) of up to 2.5m, and its big brother, the E-type which has 3m cylinders allowing it to work in sea states with Hs up to 4m.

When we reported on the Ampelmann it had just been installed on its first offshore wind assignment, on board the Jumbo Javelin for transferring personnel during TP installation in the Greater Gabbard wind farm.

Coincidently Offshore WIND was on board the Jumbo Javelin during the last TP installation trip and we were able to witness its performance at first hand.

The Ampelmann was introduced in the offshore wind industry for the safe transfer of personnel, but it has also proven to be suitable for assisting in fuelling and grouting operations by supporting the hoses, and also in the transfer of small cargo. To facilitate the latter the company created the KIB, a basket that can be mounted on the tip of the gangway for loads of up to 100 kilos. With the use of a ‘butler’ a cargo capacity of 300 kilos is possible. Mr van der Tempel: “We picked up from several clients that they had found there was also a need for larger cargo transfers which at that time were being handled by auxiliary cranes that needed to be fitted on a vessel or being transported by support vessels. That’s how we started to develop the Cargo Transfer System (CTS).”

The first concept of the CTS goes back two years ago when the company attempted to make a prototype, land-based crane, but this turned out to be unsuccessful. Mr van der Tempel: “We have however learned a lot from this experience and together with our clients we have spent the time following this test improving the concept.”

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The CTS, as it is today, uses the same hexapod configuration with 3m cylinders, but the gangway is now equipped with a 32m crane boom capable of lifting loads up to a maximum of 8.5t, up to 30m above sea level. When the unit is required to work in a crane configuration the folding crane boom, hinged at the tip of the Ampelmann gangway, is released from the side of the gangway and is swung around and locked. The whole system, including the 2 x 15ft power pack and tool container, weighs 130t and takes in 11m x 11m of deck space. As with the conventional Ampelmann E-Type there are 2 Ampelmann Operations Operators needed to control the system. Other personnel include 2 banksmen, 2 riggers, a crane operator, and a lift supervisor. The CTS can operate in seas of up to 2.5m Hs.

Offshore wind operation

The system is best suited for fitting on vessels that fall in the category between small support vessels and the heavy installation vessels, such as supply vessels of between 65m and 80m and with accommodation for 40 persons. It is ideal for use during both the installation phase and, once a wind farm is in operation, for planned maintenance. With a CTS on board a vessel there is no need for auxiliary cranes or use of helicopters or support vessels to transfer the cargo load onto the landing platform of a turbine. There are also fewer personnel needed to do the job.

Mr van der Tempel explains that he can see a slow shift in the industry. While for a long time the use of small support vessels was the common method for transferring crew and small cargo up and down the wind farms, with the wind farms being located further offshore in rougher sea states this is increasingly becoming a challenge and more costly activity. Using larger vessels that can stay longer out at sea and where, by the use of an access system, personnel can access the turbines, the vessel operators are now also able to handle larger cargo transfers to the turbine, resulting in a more cost effective alternative.

Successful testing

Although the concept was launched at the end of last year the real prototype still had to complete a full testing program for commercial production. During 3 weeks in the summer this year the new prototype underwent sea trials in the Dutch sector of the North Sea to test the engine and lifting performance of the system in several different operating positions, and the safety procedures during operation.

The first test was executed on a monopile without TP in the Dutch N7 block followed by another at a platform by NAM near the Dutch island of Ameland. The sea trials were successfully completed mid-August.

The CTS is certified by Lloyd’s Register. Mr van der Tempel: “Due to lack of industry standards specifically for access systems the conventional Ampelmann system has been certified in the ‘crane’ category.” With the CTS it is only now actually really living up to this.

This is not a stand-alone example where new standards are needed. The offshore wind industry needs more standardisation in general. Fortunately efforts are already being made although only as guidelines at this moment. The company is taking part in a joint industry project initiated by DNV for the creation of new regulations.

The oil & gas industry have already showed interest in the CTS as it fits perfectly into the load needs for general cargo. The CTS’s first assignment will be on an oil project in the North Sea. Mr van der Tempel: “Here we will monitor its performance and, if and where applicable, take care of any ‘teething troubles’. Using the lessons learned, two additional CTS units are being built but Mr van der Tempel is not planning yet to build larger stock. “The CTS is an intermediate technology and we will continue to develop this prototype.”

“This is only the beginning,” he adds. The company is working closely with their clients and is listening to their needs and feedback in order to improve their products and create new concepts. “We will further be developing the CTS and looking to expand the maximum lifting capacity, and at the same time we will continue further developing the conventional Ampelmann gangway.”

As a matter of fact, the company is at the moment working on a larger, strengthened gangway which will be able to carry a load of 1t. Keep an eye on our news site for this in future announcements!

Sabine Lankhorst

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