Difference Between Metallic Bellows And-Non Metallic Bellows

This question is asked time and again by everyone, but there are many bellow designing specifications that define the major differences between the two product.An in-depth look at how to specify different bellows and ultimately choose the right one.In this article, we explain you on the difference between single or multiple flexible metallic bellows and non metallic bellows. Well, an expansion joint is more likely used in piping systems and prevent from being crushed. But among the two which expansion joint is best for any industrial specific application? Lets us first understand the two types of expansion joints, what are these:

Metal Bellows - are the flexible elements (bellows) that are designed of a relatively thin gauge than can compress when the pressure is applied from outside the vessel (generally formed of stainless steel) they are designed to absorb mechanical and thermal movements expected in service.

Non Metallic Bellows— these are a highly flexible connector formed of natural or synthetic fabric. These non metallic bellows and convoluted non metallic dust boots are versatile seals used in wide range of application that is designed to provide stress relief in the piping industry for thermal movements and mechanical vibration.

Both the bellows have their own utility and importance. If you rate on the scale of Good, better and best. Among both metal bellow and non metallic bellows, metal bellows with the rugged multiple layer design are considered as the best. Because of its multiple layer design, these bellows are widely used in various industrial applications in piping industry. As they are considered as most reliable and trustworthy for marine industry for decades.

Advantages of metal bellows :

We deal with 8 different types of expansion joints like:

  • Higher pressure range: up to PN 100
  • Higher temperature range: up to 1000 °C
  • Besides fluids and gases, also suitable for abrasive media and solids
  • Flexible connection types possible
  • Flexible extension possibilities

Temperature :

Non metallic bellows are constructed with the synthetic material under the temperature range to 230°F, Whereas a flexible metal bellows are designed from a great range from -420°F to +1800°F. However, working pressures are reduced at elevated temperatures.

Pressure :

Depending on the diameter, the non metallic joints typically can have pressure up to 250-psi with a full vacuum rating. While in Metal bellows these are designed under the pressure capacity upto 1000-psi. The strength of metal is more than that of non metallic hence metal bellows have high advantage using in high pressure applications. However these metal bellows are coupled with thrust forces and are used in Piping systems/anchors must be designed to handle the combined load.

Conclusion :

Metal expansion joints are used more frequently than non metallic bellows primarily because of application conditions, e.g. temperatures and pressures, favor their use. According to some industry expert, metal bellows and metal expansion joints market is much larger than non -metallic market. As, a lot of efforts goes on designing metal bellows. We at pliant bellows design and manufacture high quality flexible bellows in a various sizes and material provide customize design for the application as per user specification using the guidelines of EJMA.