The displacement of the longitudinal axis of the pipe expansion joint from its initial straight line position into a circular arc. Angular rotation is occasionally referred to as “rotational movement.” This is not torsional rotation.
The dimensional shortening of a pipe expansion joint along its longitudinal axis. Axial compression may been referred to as axial movement, traverse or compression.
The dimensional lengthening of a pipe expansion joint along its longitudinal axis. Axial extension may been referred to as axial movement, traverse or compression.
A directional or sliding anchor, is one which is designed to absorb loading in one direction while permitting motion in another. It may be either a main or intermediate anchor, depending upon the application involved. When designed for this purpose, a directional anchor may also function as a pipe alignment guide. In the design of a directional anchor, an effort should be made to minimize the friction between its moving or sliding parts, since this will reduce the loading on the piping and equipment and insure proper functioning of the anchor.
A main anchor is one which must withstand the full bellows thrust due to pressure, flow, spring forces, etc.
An intermediate anchor is one which must withstand the bellows thrust due to flow, spring forces, etc., but not the thrust due to pressure.
The flexible element of a pipe expansion joint consisting of one or more convolutions and the end tangents, if any.
Devices, usually in the form of rods or bars, attached to the pipe expansion joint assembly whose primary function is to distribute movement between the two bellows of a universal pipe expansion joint. Control rods are not designed to restrain pressure thrusts.