Hitachi, Ltd.

Toji Nakatui

Yuji Yoshitomi

Hideaki Kamohara

Kenji Shimada

Iwao Sasaki

Disclosed is a tube expander adapted for use in fixing tubes to a tube plate of a boiler or a multitubular heat exchanger. The expander incorporates an elastic expanding medium adapted to be inserted into a tube to be expanded radially against a wall of a tube-receiving bore of the tube plate. The expander further includes a pressurizing rod passing through the expanding medium, a pressurizing rod head provided at one end of the pressurizing rod, a back-up ring adapted to be supported straddling said tube receiving bore and slidably passed by the pressurizing rod, and seal rings disposed at both sides of the pressurizing rod. The seal rings are made of a hard elastic material of a hardness greater than that of the expanding medium, and each of them is provided with at its portion confronting the end of the expanding medium with a conical recess.

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Hikari, Japan

Toji Nakatui