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Concentric and Eccentric Cones production specialist

What is the difference between a straight cone and a concentrical reducer? Those in the know will chuckle but for many there is still much to learn about (the manufacture of) cones. In this article we will share some of our knowledge of cones, their manufacture and application.

Antonius is known worldwide as a leading manufacturer of vessel heads and contributes regularly to projects in a wide variety of markets. Our metal shaping expertise, especially when working with larger diameters, is the foundation of our reputation as a dependable manufacturing partner. But most of our customers know us solely because of these high-quality vessel heads, while Antonius offers a much wider range of capabilities. Its these capabilities that we’ll cover in a series of articles, starting with cones.

In this article we will cover:

  • Eccentric and concentric cones
  • Conical heads application
  • Cone knuckle
  • Annealing of cones
  • Multi-part cones

Concentric and eccentric cones

If the center line of the top opening matches the bottom opening the shape is called a concentric cone. When the center lines do not match, we are talking about an eccentric cone. Both types of cones are used in a wide range of applications for a variety of purposes such as incrementors/reducers in a piping system or in combination with certain types of (pressure) vessels for other purposes. In the market, different terms are used when talking about the various types of cones. When people ask for a concentrical reducer they are talking about a straight cone, for example.


eccentric concentric cones
On the left an eccentric cone, a concentric cone is found on the right, with knuckles on both diameters
eccentric concentric cones
On the left an eccentric cone, a concentric cone is found on the right, with knuckles on both diameters

Conical heads application

A conical head is another term for what we consider to be the same product category: cones. Our cones are applied in a wide range of applications all over the world and the name is often determined by that application. Our conical heads are for example used in:

  • Process applications in food, chemical or pharmaceutical industry
  • Heat exchangers
  • Storage tanks

Often combined with our vessel heads, our cones are used in for example beer tanks. The stainless-steel cones ensure a complete unloading of the product due, in large part, to its polished interior. In other cases, we might build the cones to be resistant to corrosion. When we build our vessel heads and cones to a certain code and specifications, we often do not need to know their application. Our team is able to build cones to your exact specification and standards without compromising on quality in any way, shape or form. Would you like to know more?


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    Cone knuckle

    An interesting feature of many cones that are manufactured by Antonius is the so-called knuckle. A cone has a knuckle when the metal on one or both ends of the cone is bent to a certain radius (knuckle radius) to achieve, a straight connection to shell or pipe to decrease welding tensions on the welds between the two parts. This is an interesting feature because of the complexity it adds to the manufacturing of the cones.

    To have special tools and equipment is key to produce the shape and, depending the production method, heat treatment of the part can be necessary.


    One way to apply the knuckle is by rolling the metal. When deformation is above a certain percentage heat treatment will be necessary. But by looking creatively at the available production methods and using a press brake or another capable method, sometimes you can avoid the necessity of heat treatment and therefore save cost.

    Heat treatment of cones

    Within the applicable norm, such as ASME, the degree of deformation that is the result of knuckling/forming often calls for additional heat treatment to reduce the stress in the material. This, of course, adds to the cost, but the biggest challenge is frequently whether manufacturers have the equipment to heat treat such large workpieces efficiently. Antonius is able to efficiently perform the heat treatment of large diameter cones on-site.

    Additionally, heat treatment comes with the threat of deformation. Due to our experience with the heat treatment of a wide variety of metal shapes at different sizes, Antonius has developed several ways to prevent deformation that would lead to costly reshaping of the parts. The first of which is shows at the accompanying image, here you see a disc that is welded in the top diameter to prevent deformation. Another way to prevent deformation is not as easily illustrated, we regularly place metal ridges that support the shape of the cone. This is often applied to shapes out of material with a lower thickness.

    Heat treatment of cones
    A metal disc that is welded in the top diameter of the cone serves two purposes: allowing for easier handling and prevention of deformation

    Multi-part cones

    Larger cones are often constructed out of several parts instead of one sheet of metal. Why is that the case? There are several variables that determine the optimal way to manufacture a cone:

    • Material thickness
    • Reduce material waste
    • Availability of sheet metal

    Multi-part cones

    Known for our ability to work with the largest sheets of metal, even we have our limitations. Our equipment allows us to shape the largest sheets of metal up to a certain thickness. Beyond that thickness we need to construct the cone out of multiple parts. But this is a choice that is often primarily made to reduce waste. Due to the cone shape, the cutting loss resulting from the manufacture of a cone out of a single part is much more costly than welding two parts together. And lastly, there’s the availability of the material. Not every sheet metal is readily available in the exact size and thickness that is required. Or the price may be prohibitive. Our engineers and planners will decide on the most efficient approach and will talk you through our reasoning.


    Would you like to know more about our approach, or do you have a challenging project for us in mind? Please contact our sales team at sales@antonius.nl or call +31(0)475 439 000.


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