Vacuum insulated transfer lines (VIP)

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Rigid- and flexible vacuum insulated transfer line

Vacuum insulated transfer lines (Vacuum Insulated Piping) are the basis of almost all cryogenic infrastructures. These double-walled pipes ensure that cold liquid gases can be transported safely, without excessive warm-up, causing them to lose their liquid form. Transfer lines make the connection, for example, between a tank and an application or between an ASU (Air Separation Unit) and a transfer vehicle.

To ensure optimal insulation, Demaco supplies vacuum insulated pipes with a multi-layered radiation shield. As mentioned on our page about vacuum technology, the combination of a vacuum environment and a radiation shield ensures that various forms of heat loss are virtually eliminated.

Demaco supplies two types of transfer lines

1. Rigid vacuum insulated transfer lines

The most common transfer line is the rigid type, which we supply in pre-fabricated sections. These pipe sections (or spools) are rigid and must be carefully measured before installation. Even if they are just a fraction too short or too long, they will not fit into the designed system.


The above image shows how our rigid vacuum insulated transfer lines are constructed.

As you can see, the pipes contain an inner and an outer tube. Via the pump valve near the black cap, the space in between is vacuumed, the yellow spacers are in place to ensure that the two pipes do not touch each other.

Because the inner pipe becomes a lot colder than the outer pipe, the inner pipe often shrinks several millimeters per meter while in use. To prevent ruptures, a so-called compensator is installed between the two yellow spacers. This flexible section absorbs the shrinkage of the inner pipe.

Because of minor flow loss, the stability, high quality, and attractive appearance, many of our customers choose rigid piping.

2. Flexible vacuum insulated transfer lines

For projects requiring more flexibility, we offer flexible vacuum insulated transfer lines. This type of pipe provides a slightly lower insulation rating than rigid pipes but has significant advantages in case:

  • A temporary structure is build
  • Pipeline routes cannot easily be measured due to obstructions
  • The line will be connected to a moving or vibrating machine
    the option to correct measurement and dimensional errors must remain open.

The flexible pipe is constructed the same as the rigid pipe, but due to its flexibility, it has a slightly larger diameter compared to a rigid line with the same throughput. The surface structure is different, which leads to somewhat more energy loss.


In our factory, we produce piping segments that are connected on site. These segments can be up to 12 meters long and can vary significantly in diameter. Often the pipes have a relatively small diameter of DN15/25 or 1 inch, but for large-scale users, this can go up to 10 inches or more.

Our pipes are devised for standard working pressures of up to PN40 and are used for: N2, CO2, O2, Ar, LNG, H2, and He, to name a few.

Higher pressures, nonstandard gases, or larger diameters are, of course, possible. We have the knowledge and technology to develop these pipes; please contact us via our contact page and find out what we can do for you.

Care to know more? Download our product sheets Vacuum Insulated Piping,Vacuum Insulated Flexible, and Vacuum Insulated High Flex for more information and more detailed specifications.

Applications of vacuum insulated transfer lines

High-quality piping allows cold liquid gases to be transported safely with the lowest possible energy loss. This is important for all the industries we serve. For example, liquid nitrogen for the food and automotive industry, LNG & hydrogen for the marine industry, the air separation industry, and liquid gas transportation to temporary storage units and onward transportation.

Demaco’s piping is always tailored to customer specifications, thus ensuring it perfectly matches the customer’s needs for a specific project. As a result, the field of application of our piping is vast and diverse.

For more information on the industries in which our cryogenic products are used, check our industries page here.

Accessory products

Our pipelines are supplied in sections that are connected on-site with the use of special couplings

We supply two different types of couplings:

1. Welded couplings

Welded couplings make a permanent connection between two sections of a pipeline. A solid welded coupling ensures maximum safety and offers the best protection against entering heat. Two types of insulation can be used with welded couplings: Vacuum or Perlite. Installing a welded coupling requires specialized equipment, knowledge, and experience.

Care to know more? On our Welded Coupling product sheet, you can find more information about this type of coupling, including pictures and specifications.

2. The Johnston coupling

The Johnston coupling offers more flexibility than the welded coupling. The coupling consists of a male and female connector, which can be easily connected and secured. No welding or special knowledge is required.

The Johnston coupling permits a slightly higher heat inleak than the welded coupling but has the advantage of being easy to install, remove or re-position. It also offers the advantage of letting customers install these pipe sections themselves when necessary.

Want to know more? View the Johnston coupling product sheet for more information on this coupling, including photos and specifications.

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