Metallic Bellows

Metallic bellows, also known as metal bellow, can save you money. When there is a piping system, and there is not enough room for loops. Don’t worry. Use a metal expansion Joint, also known as a metal below.

Metal Bellow

There are two main types of metal bellows – formed and welded. Formed bellows are produced by reworking tubes, normally produced by deep drawing, with various processes, including cold forming (rolling), electroforming, and hydroforming. They are also called convoluted bellows.

Welded bellows (also called edge-welded or diaphragm bellows) are manufactured by welding several individually formed diaphragms to each other. The comparison between the two bellows types generally centers around cost and performance. Hydroformed bellows generally have a high tooling cost but, when mass-produced, may have a lower piece price. However, hydroformed bellows have lower performance characteristics due to relatively thick walls and high stiffness.

Welded metal bellows are produced with a lower initial tooling cost and maintain higher performance characteristics. The drawback of welded bellows is the reduced metal strength at weld joints, caused by the high temperature of welding. Electroformed bellows can be produced with modest tooling costs and thin walls (25 micrometers or less), providing them with high sensitivity and precision in many exacting applications.

Another area of comparison is in metals of construction. Hydroformed and rolled bellows are limited to metals with high plastic elongation characteristics. In contrast, welded bellows may be fabricated from a wider variety of standard and exotic alloys, such as stainless steel and titanium, and other high-strength, corrosion-resistant materials. We can produce electroformed bellows of nickel, high-strength alloys, and copper.

Metal Pipe Bellow Manufacturer

Welded bellows can be fabricated from various exotic metals and alloys, whereas formed bellows are limited to alloys with good elongation – brass being a prime example. Welded bellows are not fabricated from brass because of their fundamentally poor weldability. Other advantages to welded bellows include compactness (higher performance in a smaller package), ability to be compressed to solid height with no damage, resistance to nicks and dents, and dramatically greater flexibility.

The welding of metal bellows is a microscopic welding process, typically performed under laboratory conditions at high magnification.

Hydroformed bellows are produced by forcing a metal tube to expand under hydraulic pressure inside a bellows-shaped mold and assume the convoluted shape of the mold.

Electroformed bellows are produced by plating metal onto a bellows-shaped model (mandrel) and the subsequent mandrel removal by chemical or physical means.

Industrial Metal Bellows

Bellows, welded or convoluted (formed), are used in a large number of industrial applications. Below you will find a few:

  • Oil and Gas refinery.
  • LNG Plant.
  • Petrochemical
  • Offshore
  • Marine
  • Pumps
  • Pipelines
  • Thermal Expansion or Contraction
  • Exhaust Systems
  • Aerospace

Exhaust Bellows

Running engines cause self vibration. To compensate for those movements and temperature differences resulting in thermal expansion, bellows connect the exhaust gas pipes.

Piping expansion joint: In this application, bellows are formed in series to absorb thermal movement and vibration in piping systems that transport high-temperature media such as exhaust gases or steam.

Metal bellows are also used in other products and market segments, including medical applications like implantable drug pumps, industrial actuators, aerospace applications such as altitude sensors, and fluid management devices (accumulators, surge arresters, volume compensators, and fluid storage). Pipe bellows are also found in space applications, providing reservoirs with potable water and accumulators to collect wastewater.

Metal Bellows Pipe Movement

Metal bellows consist of individual convolutions that have uniform inside and outside diameters, constant pitch or spacing, and the planes of each convolution are parallel. The flexibility of the convolutions gives the bellows the ability to absorb axial, angular, and lateral displacements – individually or in combination.

Axial motion is the extension or compression of the metal expansion joint along the longitudinal centerline (x-axis) with the ends remaining parallel.

Metal bellows lateral or offset motion is the displacement of the ends perpendicular to the longitudinal centerline with the end planes remaining parallel. The longitudinal centerline is shaped into a compound curve, with the convolutions deforming similarly.

Pipe Bellow

Metal bellow angular motion is the rotation or angulation of the end planes relative to each other, which results in the longitudinal centerline becoming an arc. The convolutions are extended along the outer radius of the arc and compressed along the inside radius.

Torsion or twisting is rotation around the longitudinal centerline of the pipe expansion joint and is sometimes confused with angular motion. Metal bellows do not absorb torsional displacement, and although a metal bellow can react to torsional moments, they should be avoided if possible.

Metal bellows can absorb these movements as individual motions or in any combination and multiple planes. Aside from the physical limitations of deflecting a metal bellow without damaging it, the design is normally based on specified cyclic movements for a given fatigue life at the operating pressure and temperature. The accepted method for equating axial, lateral, and angular motions is outlined in the Standards of the Expansion Joint Manufacturers Association, Inc. The following equations are based on this method but are for complete metal bellows – not per convolution as described by the Standards.

A typical metal bellows design over a range of diameters has 12 inches convoluted (L) length and is rated for 3 inches compression (Ec) with zero lateral and angular movements.

The correct specification of metal bellows movement requirements is one of the essential factors in the successful application of this product. The axial, lateral, and angular movements must be realistically stated along with the corresponding cycle life. One of the most common mistakes made is to overstate these values to obtain a conservative design. Over-emphasis of any parameter can jeopardize other elements of the design and result in unnecessary costs. Several good rules to remember when specifying motions of the metal bellow include:

  • Separate the cyclic and noncyclic motions, such as installation displacements.
  • Distinguish between normal operating movements and upset conditions.
  • When comparisons are made to the manufacturer’s rated motions, be sure to distinguish between concurrent and nonconcurrent values.
  • Realistically state fatigue life requirements for the metal bellow. Cycle life is not proportional to rated travel. Small changes of displacement can result in substantial cycle life changes and vice versa.
  • Avoid large lateral offset requirements for single metal bellows – particularly for large diameter bellows.

What is a Metal Piping Bellow?

Industrial metal bellows joints are versatile because they are manufactured with different tensile strength, chemical and physical properties. When manufacturing industrial metal bellows in a bellows machine, there are various materials to choose from. Each material has its own advantages, use, depending on the industrial metal bellows application.

Whether it is for flight control, safety, firing mechanism, pipes, the bellows play a crucial role in the efficiency of the various industries. They are presented as the most flexible tool for many types of industries. These circular tubes are too flexible to expand or compress under pressure. In addition, they also have sufficient capacity to absorb a lot of heat and can remain in good condition for a long time. The bellows material in plastic, steel, rubber, or fiber usually depends on its purpose.

Why are Bellows Used?

In most cases, industrial metal expansion bellows helps absorb vibration and absorb movement when transferring high-temperature products such as exhaust fumes, electricity, etc. In addition, they are useful for other purposes, such as regulation and earthquake movement. Bellows also works as a helper for any high-pressure or high-performance process. They are also instrumental when it comes to minimizing the process and by-products. Some key accessories needed to use the bellows effectively are liners, covers, particle barriers or flushing connections, and perimeter bars.

Industrial Applications of Industrial Bellows

Industrial metal bellows are widely used in mechanical and hydraulic applications. The mechanical operation uses bellows fill with a known liquid that depends on compressing or expanding to temperature changes. The liquid expansion will predictably take place. The response percentage and the bellows can be used to provide accurate positioning in a machine assembly. Equivalent to thermal activation, a pressure change can compressor control Bellows extension a mechanical operation.

One of the interesting applications of Bellows is used for the rotating display. Because of the low weight and rotation stiffness, while it remains flexible on their main axis, the bellows connected to their ends with waves that are not well aligned or linear, radial, or the angle change can be used as coupling or rotation indicator.

The shape of the bellows makes it possible to efficiently transmit the rotation energy without problems found in the claws. Encode this kind of bellows because they depend on the accuracy of rotation.

Industrial metal bellows are also used for hydraulic applications: positive displacement pumps, valve seals, and volume and fluid compensation electrical applications. Industrial metal bellows prevent leakage without these being necessary rings. If used as flexible, they offer pumps hermetic seals without friction loss of force, higher printing efficiency.

They can finally do that is used as a traditional mechanics. To prevent seals on an actuator Pollution from the grooves of the tree.

Industrial Metal Bellows Accumulators In The Oil and Gas Industry

Hydropneumatic accumulators with metal bellows as a separating element between the compressible gas cushion and the working fluid. The separating element is designed as bellows or as metal bellows.

Metal Compensators (MEJs) are also known as metal expansion joints or bellows. A bellows element used in a piping system is an assembly of more than one fold in series with the shape of the bend to withstand internal pressures. Thermal expansion, mechanical vibration of pumps, traction fans, compressors, turbines, motors, tanks, and other equipment, but sufficiently flexible to allow axial, lateral, and angular deflections.

Axial compensators are designed to absorb the axial expansion and compression movements. The length of the extension in a neutral position is called free length. The longest life is achieved by using axial displacement in both directions as extension and compression. In a unilateral direction, we suggest installing the compensator under “bias.” The life of the compensators depends on the correct installation.

Metallic Bellow

Dannenbaum LLC supplies rectangular and round, custom industrial metal bellows and fabric expansion joints delivered on time. Our rugged fabric expansion joints and industrial metal bellows expansion joints are precision engineered to your specifications to withstand heat, pressure, movement, vibration, and abrasion in the most challenging industrial environments. Dannenbaum LLC also offers the design and manufacture of fabricated industrial dampers. Dannenbaum fabric expansion joints, industrial metal bellows, and industrial dampers are installed throughout the United States and worldwide. Rush delivery is available. Experience the difference — call us today for a quote.

Metal Bellows Expansion Joints

Dannenbaum LLC supplies bellows joints and is recognized as a leader within the expansion joint industry. Our company has engineering principles, stringent quality standards for all products, including metal bellows expansion joints. Our skilled staff focuses on stress for piping for metal bellows expansion joints. 

What is a Metal Bellow Expansion Joint?

Metallic bellow expansion joints absorb movement in a pipeline, protecting adjacent pipes and equipment from damage.

To make the bellows joint, we would attach end fittings to the bellow. Tubing is used to make the cylinder. Select the correct material and thickness to handle the pressure and temperature.

The interplay between alloy, wall thickness, and convolution geometry determines what proportion movement an expansion joint can absorb.

When to Use a Metallic Bellows Expansion Joint?

Sometimes a flexible metal hose is a better choice for an application than a bellow. This all depends on axial movement, vibration damping, exotic material requirements, space limitations, size requirements.

It helps to use STAMP when inquiring about an expansion joint. Please provide the following:


  1. Size
  2. Temperature
  3. Application (movements—axial, lateral, and angular)
  4. Media
  5. Pressure