Tank storage - tank seals, floating and self-supporting roofs

Our suppliers, Imhof Tank-Technik GmbH and Vacono Aluminium Covers GmbH, are European leaders in manufacturing and developing tank seals and floating roofs for open and closed cistens, as well as self-supporting aluminium weather domes.

The objective is to protect and optimise the amount of stored product, reduce environmentally harmful emissions and increase safety. Together with our suppliers, we offer complete solutions - design, manufacture and installation - focusing on safety, quality, environment and long operating life.

Choose the right tank storage equipment for increased safety and reduced environmental impact

Each cistern is unique and tank storage equipment needs to be customised to achieve the most effective solution. To develop an environmentally friendly, safe and sustainable solution, there are a number of factors that affect the choice of product and type of solution.


HL Hansa Engineering AB
Hans Linder Spray nozzles & systems, Tank cleaning, Safety showers, Tank storage equipment I look forward to providing product advice and solutions! Let's meet via a video call or a site visit. You can also phone or email us, of course.
  • Is it an open or closed cistern?

    A major difference between an open and a closed cistern is the actual tank construction, and how it is affected by wind, rain and snow.

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  • Is the tank completely round or slightly deformed?

    Apart from the question if the tank is completely round or slightly deformed, it is important to know whether the tank wall is an 'overlap' construction or has an even surface.

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  • What type of product is stored in the tank today? Future stored product?

    A very important question is what type of product is stored in the tank and if there is a possibility that another type of product will be stored in the future. The type of stored product is absolutely crucial when it comes to choosing the type of sealing solution and sealing material, as well as ...

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  • How can external factors such as rain, snow and wind affect the tank?

    External factors such as rain, snow and wind can affect the tank and this needs to be taken into account in order to select the right type of external floating roof seal and work out the correct dimensions. For example, strong winds in coastal areas ...

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  • What is the objective of replacing the tank storage equipment?

    The reasons for changing the tank storage equipment is important to know in order to ensure that the most optimal solution and the right type of product is supplied. Improved efficiency, i.e. reduced emissions, leads to less environmental impact but also reduced loss of product, which means lower costs. ...

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  • What other factors may be important when changing tank storage equipment?

    Other factors to consider when replacing tank storage equipment may include: Timeframe for emptying and any repair work on the existing tank Manufacturing and delivery time Installation - How much time is estimated for installation? Is an on-site supervisor required? The sealing solution has a ...

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Start-up meeting, project review and proposed solution

To deliver the optimal solution, it is important to go through in detail various factors that affect product choice, type of solution, investment objective, and other requirements at an early stage of the project.

Start-up meeting

A start-up meeting is important to identify a variety of factors that can affect the choice of equipment and solution to achieve the most efficient and sustainable results. At this stage, current regulatory requirements are also discussed.

We pefer to do the start-up meeting as a site visit or web meeting, depending on your preference.

Project review

During the start-up meeting, we review existing documentation and tank data (tank cards, measurements, etc.). Sometimes it is necessary to supplement the information with, for example, a roundness and rim space measurement to optimise the solution and minimise emissions.

Examples of other important factors to discuss and take into account include:

  • Type of product stored today and in the future
  • Tank construction - surface area, open or closed tank, type of floating roof, etc.
  • Desired efficiency
  • Regulatory requirements
  • Impact of external factors such as rain, snow and wind
  • Timeframe for emptying the tank, any repair work on the existing tank, delivery and installation
  • Investment objective

Summary and proposed solution

Using the information discussed during the site visit, we prepare a summary that we review with the client to ensure that we agree on the scope of the project.

The next step is that we put together and present a proposal for a sustainable and efficient solution, focusing on reducing emissions, maximising tank utilisation, achieving the highest possible safety rating and ensuring a long operating life.


Open cisterns with external floating roofs

An open tank with an external floating roof is used to store large quantities of petroleum products, biofuels, etc. The open tank consists of a cylindrical shell and a roof that floats directly on top of the stored product. The floating roof rises and falls with the liquid level in the tank.

An advantage of an open tank with an external floating roof compared to a closed tank without a floating roof, is that there is no room for evaporated product as the roof floats directly on top of the product. This means that the amount of evaporated product is minimised, which also reduces the risk of fire.

To further reduce evaporation and emissions, a seal is installed around the floating roof. The seal seals tightly against the tank wall surface. There are also seals for roof supports and guide poles to further minimise emissions from the tank.

To prevent rainwater and snow from entering the tank and running down the inner wall of the tank, a water-repellent seal is recommended when storing white products, such as petrolium. The water-repellent seal ensures that the stored product is not contaminated and that there is no corrosion at the bottom of the tank due to water accumulation.

The floating roof has roof supports that hang down into the stored product. When the level of product stored in the tank is low, the roof will no longer float on the product but will be supported by the supports.