Laminated Bellows Expansion Joint
In this paragraph, I’m going to talk about Laminated Bellows Expansion Joints. Firstly they are designed for installations where the principal movement is axial. Secondly, standard designs are 2” through 14” NPS with 2” or 3” axial compression. Lastly, service conditions are 150 PSIG or 300 PSIG to 500°F.
Further, the bellows element is put into the design to provide the minimum effective area and resulting pressure thrust—moreover, the laminated construction results in the optimum cycle life and lowest possible spring constant. However, a stainless steel flow liner is standard, with a slight reduction of flow area. Common joints are available from stock.
- Sizes 2″ through 14″ IPS.
- Design conditions of full vacuum to 150 and 300 PSIG at 500°F.
- Axial travel up to 3.0 inches
- Maximum flexibility and extended life
- Low spring rates and pressure thrust
Laminated Bellows Expansion Joints
Pipe expansion or contraction resulting from temperature changes is independent of line size; however, the bellows elements of small diameter expansion joints have less ability to absorb motion than larger sizes because of restrictions on the corrugation size. Therefore, it recognizes these shortcomings, Laminated Bellows Expansion Joints for applications that involve axial movement.
The bellows elements are designed with up to four individual thicknesses or laminations of precision stainless steel foil. This design combines the high flexibility of thin material while providing the pressure resistance of multiple laminations. As a comparison, a bellow made from four plies of 0.008″ thick material. Will have the same pressure rating as a single thickness of 0.016″ thick. But the laminated construction will deflect twice as much and requires only one-half the force to compress.
Laminated Bellows
The bellow is put on the inside of the pipe. This method has the advantage of reinforcing the bellows neck and attachment weld. Thus reducing the effective area of the bellows and the corresponding pressure thrust. The pressure thrust force of Laminated Bellows Expansion Joints ranges from 40–70% of comparable products.
Laminated Bellows Expansion Joints
All Laminated Bellows Expansion Joints include a stainless steel flow liner. Therefore, the flow liner eliminates added pressure drop resulting from the bellows. Also, it protects the bellows from the flow. And as a precaution, it provides help for the bellow in the event of over-pressurization. As a result, they offer the most reliable yet economical pipe expansion compensation available. The all-metal welded construction permits service to 500°F for standard models.
Laminated Bellows Expansion Joints are designed for installations where the principal movement is axial. Therefore, the piping system must include anchors to react to the force produced by pressure thrust. Also, the pipe alignment needs to be maintained by guides.
Read about expansion joints.