Q: What is the maximum pressure the bellows can take?

A: Up to 1000 PSI.  The specific application requirements will help us calculate the actual maximum pressure.  The bellows outside diameter and whether the pressure is external or internal will have the greatest impact when determining the maximum pressure.  When selecting bellows a smaller diameter and size with the shortest distance from inside diameter to outside diameter will achieve highest pressure differentials.  Using a thicker bellows material will increase pressure differential but would reduce maximum axial stroke and or cycle life.

Q: What metal can be used to make edge welded bellows

A: Any metal that can be easily formed, blanked, and welded. The common materials used at BTLLC are:

  • Stainless Metals: 304L, 316L, 321, 347, AM350
  • Nickel Metals: Inconel 600, Inconel 625, Inconel 718, Inconel X750, Hastelloy C276, Haynes 242
  • Titanium Grade 5

Q: What are the total number of cycles an edge welded bellows can last?

A: This all depends on the customer’s design criteria. Axial stroke, lateral and angular offsets, pressures, media, temperature, cycle rate, and environment are just some of the variables that affect cycle life, so it is important to know all of these variables before predicting cycle life.

A bellows made from 304L, 316L, 321, 347, or titanium, with vacuum on the inside of the bellows, will typically be designed for cycle life less than 1,000,000.

A bellows made from AM350, Inconel 600, Inconel 625, Inconel 718, Inconel X750, Hastelloy C276, or Haynes 242, with vacuum on the inside of the bellows, will typically be designed for greater than 1,000,000 cycles.

Q: How can I get the bellows force for a given deflection to be lower?

A: Here are a three ways to reduce force.  First, the easiest way is to reduce the bellows material thickness but depending on bellows performance requirements it may reduce the cycle life.  Second, is to make the bellows longer by adding convolutions.  The more convolutions a bellows has the lower the force will be if axial stroke length is unchanged.  Third, is by changing the bellows material.  Stainless steel we use all have similar a force but Titanium bellows will have about half the force of an AM350 or 316L stainless steel bellows.