Expansion Joint Lateral Deflection & Angular Deflection

Expansion Joint Lateral Deflection & Angular Deflection

Lateral Deflection

Lateral refers to the direction perpendicular to the centerline of the expansion joint(in any plane). Other terms for this deflection are PARALLEL OFFSET and TRANSVERSE. This movement occurs with both of the ends of the expansion joint remaining parallel to each other , with their centerlines being displaced, or no longer coincident. When analyzing the deflections in a piping system, it is not uncommon to find that different lateral deflections can occur in more than one plane. Since an expansion joint is round, these various deflections must be resolved into a single resultant lateral deflection, in order for the bellows to be properly selected in terms of the rated LATERAL DEFLECTION shown in this catalog. The magnitude of the resultant LATERAL DEFLECTION is the square root of the sum of the squares of the individual deflections. The planes of the various deflections must also be clearly understood if the expansion joint is to contain structural components such as hinges, which may inhibit movements in certain directions , and if the individual deflections can occur separately during the life of the expansion joint.

                                Elbow Pressure Balanced Expansion Joints

Angular Deflection 

When an expansion joint experiences bending about its center, which is on the centerline and halfway between then ends of the bellows, this deflection is referred to as ANGULAR . It can occur in any plane that passes through the centerline , but the plane should be clearly indicated if the expansion joint is more complicated than the simplest type, i.e., only a bellows with flanges or pipe ends. As in lateral movements,piping analyses may reveal angular deflections occurring in more than one plane. With ANGULAR DEFLECTION, the basis for the proper selection is the maximum of the various deflections, and not the vector sum as in the lateral case. Multiple ANGULAR DEFLECTIONS in multiple planes produce a single ANGULAR DEFLECTIONS in a single resultant plane. As in lateral deflection,this plane must be understood if structural components are to be used.

                                 12” Universal Metallic Expansion Joint