Spiral Tubing Corporation

Robert W Perkins

Helically corrugated tubing with corrugations of variable depth is manufactured in a twisting machine by rotating one end of a deformable tube relative to the opposite end and simultaneously applying axially directed forces to the tube to progressively develop the helical corrugations in the tube wall. The depth of the corrugations is varied by means of a tapered mandrel which is located within the tube while the corrugations are being formed. Tubing sections with variable depth corrugations define flow paths in which the effective cross sectional area varies correspondingly, and such sections are useful in various heat exchangers.

Corrugated tubing with variable depth corrugations and method of making

Helically corrugated tubing with corrugations that have a gradually changing pitch from one end to the other is manufactured in a twisting machine by rotating one end of a deformable tube about the tube axis relative to the opposite end and simultaneously applying axially directed forces to the tube to progressively develop helical corrugations along the tube wall. The ratio of the torque and the axially directed forces applied to the tube is continuously varied to produce corresponding variations in the pitch of the corrugations. Tubing sections in which the pitch of the corrugations increases gradually from one end to the other are used in shell-and-tube or tube-in-tube heat exchangers and define flow paths having cross sectional areas which increase correspondingly.

Method of making corrugated tubing with graduated pitch

Helical corrugations are formed in a tube having a cylindrical wall by generating pressure radially of the unsupported tube wall at localized areas distributed around the tube circumference. While the radial pressure is being generated, twisting of the tube about its own axis is initiated and as a result, radial deformation of the unsupported tube wall takes place. By controlling the axial length of the tube while it is twisted, the radial deformations develop into flutes which grow axially along a selected helical path in the tube wall.

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Hamden, CT, United States of America

Robert W Perkins