Shape memory coupling
Encyclopedia
Shape-memory coupling is a system for connecting pipes using shape-memory alloys. In its typical form the technique uses an internally ribbed sleeve of alloy such as Tinel that is slightly smaller in diameter than the pipes it is to connect. The sleeve is cooled in liquid nitrogen
then, in this low-temperature state, mechanically expanded with a mandrel
to fit easily over the two pipe ends to be joined. After fitting, it is allowed to rewarm, when the memory effect causes the sleeve to shrink back to its original smaller size, creating a tight joint.
It was first produced in the late 1960s or early 1970s by the Raychem Corporation under the trade name CryoFit. Manufacture of these couplings for aerospace hydraulic connections was later transferred to AMCI (Advanced Metal Components Inc.) and then later to Aerofit Products Inc. Additional products using the same shape-memory alloy technology are produced under Cryolive and CryoFlare trade names.
Liquid nitrogen
Liquid nitrogen is nitrogen in a liquid state at a very low temperature. It is produced industrially by fractional distillation of liquid air. Liquid nitrogen is a colourless clear liquid with density of 0.807 g/mL at its boiling point and a dielectric constant of 1.4...
then, in this low-temperature state, mechanically expanded with a mandrel
Mandrel
A mandrel is one of the following:* an object used to shape machined work.* a tool component that grips or clamps materials to be machined.* a tool component that can be used to grip other moving tool components.- Variants :...
to fit easily over the two pipe ends to be joined. After fitting, it is allowed to rewarm, when the memory effect causes the sleeve to shrink back to its original smaller size, creating a tight joint.
It was first produced in the late 1960s or early 1970s by the Raychem Corporation under the trade name CryoFit. Manufacture of these couplings for aerospace hydraulic connections was later transferred to AMCI (Advanced Metal Components Inc.) and then later to Aerofit Products Inc. Additional products using the same shape-memory alloy technology are produced under Cryolive and CryoFlare trade names.