Expansion joint
They are commonly found between sections of buildings, bridges, sidewalks, railway tracks, piping systems, ships, and other structures.
Modular multiple-gap expansion joints can accommodate movements in all directions and rotations about every axis.
The total movement of the bridge deck is divided among a number of individual gaps which are created by horizontal surface beams.
The individual gaps are sealed by watertight elastomeric profiles, and surface beam movements are regulated by an elastic control system.
Certain joints feature so-called “sinus plates” on their surface, which reduce noise from over-passing traffic by up to 80%.
[4] Concrete decking (most typically in sidewalks) can suffer similar horizontal issues, which is usually relieved by adding a wooden spacer between the slabs.
Dry, rot-resistant cedar is typically used, with a row of nails protruding out that will embed into the concrete and hold the spacer in place.
A bellows is made up of a series of one or more convolutions of metal to allow the axial, lateral, or angular deflection.
Pipe expansion joints are necessary in systems that convey high temperature substances such as steam or exhaust gases, or to absorb movement and vibration.
A typical joint is a bellows of metal (most commonly stainless steel), plastic (such as PTFE), fabric (such as glass fibre) or an elastomer such as rubber.
Expansion joints are also designed for other criteria, such as noise absorption, anti-vibration, earthquake movement, and building settlement.
Expansion joints with metal bellows are designed to accommodate certain movements while minimizing the transfer of forces to sensitive components in the system.
[12] After the entire product is built up on the mandrel, it is covered with a winding of (nylon) peel ply to pressurize all layers together.
These rubber expansion joints are manufactured on a cylindrical mandrel, which is wrapped with bias cut fabric ply.
New technology has been developed to wind rubber and reinforcement layers on the (cylindrical or bellows-shaped) mandrel automatically using industrial robots instead of manual wrapping.
Another aspect of using industrial robots for the production of rubber expansion joints is the possibility to apply an individual reinforcement layer instead of using pre-woven fabric.
Limit rods are used to prevent bellows over-extension while restraining the full pressure thrust of the system.
[19] Also, periodically inspect the expansion joint throughout the operating life of the system in order to check for external corrosion, loosening of threaded fasteners and deterioration of anchors, guides, and other hardware.
Copper expansion joints are excellent materials designed for the movement of building components due to temperature, loads, and settlement.
