A floating flange is a connector that provides flexibility in piping systems, which reduces vibration and allows for movement. Pipes carrying hot or cold fluids can change shape due to expansion or contraction, resulting in stress on joints and fittings. Adding a floating flange allows sections of pipe to move separately from each other. The term "flange" refers to a connection point that can be attached to another pipe, either by bolting the flanges together or screwing one flange into the next section.
There are two types of floating flange systems; rigid pipe with movable flange connectors on each end, and flexible pipe with connectors. Rigid connectors are produced from steel pipe with a compression fitting containing a gasket at each end. At the connections, the gasket will fit against the end of the next section. When the flanges are tightened, the gasket compresses and stops leaks, but some movement can still occur if needed.
Another type of floating flange is a flexible pipe with loose or fixed flanges on each end. Loose flange systems do not weld or attach the flanges, allowing them to move or make connections to pipe that is not lined up correctly. Rigid flange sections are welded or glued to maintain a constant attachment angle, but the flexible pipe can move as needed to make the connections line up.
Pipe materials can vary widely, and having the correct material for the specific fluids being moved is important. Low pressure systems may use plastic pipe with screwed connections to reduce weight and cost. Corrosive materials may require natural rubber-based or artificial elastomers to reduce wear. Some elastomer-based floating flange systems use embedded wire or cable to permit even higher pressures, yet remain flexible.
Flexibility can be accomplished by the materials themselves, such as plastic pipe, or by adding flexible joints or using braided coverings. Flexible joints can be used with rigid pipe, with a gasketed fitting in the middle that can move to allow mismatched connections. Braids are woven steel or strong fibers that can resemble a cloth covering, allowing higher pressures with flexibility.
Using floating flange piping requires some planning, because these systems cannot be flexed or stretched beyond certain limits. If the misalignment is extreme, it may be advised to have a custom pipe connection manufactured, because a flexible connection may be over-stressed and can fail. Minor adjustments and vibration elimination are the two best uses for flexible connection devices.