Joining tubing with a gas tight seal

摘要

A method of joining tubing with a gas tight seal is provided by a female tube (1) and a male tube (2). At least one of the internal surface of the tube (1) and the tube (2) is provided with a grooved surface (4), the surface (4) being of harder material than the surface on the tube with which mating is to be effected. The internal diameter of the female tube and the external diameter of the male tube norminally have an interference fit at ambient temperature. To secure the tubes together, the female tube (1) is expanded by heating and the male tube (2) is contracted by cooling with liquid nitrogen. The male tube (2) is then inserted into the female tube (1) and the tubes brought to ambient temperature. By virtue of the grooving (4) biting into the mating tube (1), so increased surface area contact and frictional engagement is achieved.