Ferrules denote either specialized strengthening rings and caps placed on components, or fittings used in heat exchangers, boiler flues and condenser tubes. In the case of the latter applications, ferrules are used to protect inlets. Additionally, ferrules serve as connecting joints for multi-part tubes and rods. They can also be attached to wires and cables using a crimper to add strength and provide easier manipulation to the wire-end.
In the case of hose and tube ferrules, a wide range of materials are available, including aluminum, stainless steel, brass and various synthetics. Fittings must be fabricated to proper standards for the application at hand. Styles manufactured are
hose to hose, expanders, pipe adapters and reducers, as well as others. Important measurement characteristics are the inner or outer diameter of the pipe to be fit and the original pipe. Ferrules should also include a psi rating, which help purchasers determine their suitability for the operation. Ferrules are also used for welding hose and other similar applications.
Ferrules used for boiler applications are referred to as inserts or refractory ferrules. They are regularly manufactured from materials such as alumina, ceramic and zircon, as well as other strong, heat resistant substances. Ceramic is one of the most widely used materials, as it has exceptional bonding characteristics, and is chemically stable. Due to the nature of the applications in which they are used, chemical stability is also extremely important, as part degradation can lead to much larger problems. The environments in which ferrules must perform can be high in potentially destructive chemicals, such as sulfur and hydrogen sulfide, which must be accounted for before purchase.