Plug for heat exchanger tubes

A tube plug for sealing the end of a tube, comprising:

• a cylindrical housing member sized for insertion within the end portion of said tube,
• said housing member having a longitudinal blind bore comprising a smooth portion communicating with a threaded portion,
• locking means mounted on said housing member for locking said inserted housing member against rotation relative to said tube, and
• an insert member having a threaded end portion received within the threaded portion of said bore, an enlarged portion positioned to be drawn within said smooth portion of said bore in response to rotation of said insert member threaded end portion in said bore threaded portion, and a tapered portion between said threaded end portion and said enlarged portion,
• said tapered portion being formed separately from said threaded end portion and said enlarged portion of said insert member in the form of a truncated cone with a threaded bore therethrough for receiving said threaded end portion of said insert member, and
• said tapered portion and said enlarged portion being sized to cause said smooth portion of said bore to expand, thereby providing a seal between said housing member and said tube.

A tube plug for sealing an end of a tube comprising:

• a body portion sized to be received within said tube with a minimum of clearance;
• said body portion having a friction enhancing outer surface and a central bore therein, with a portion of said bore having a smooth inner surface and a smaller radiused portion having an internal thread;
• locking means comprising an eccentric ring rotatably mounted on a post projecting axially from an end of said body portion to prevent said body portion from rotating within said tube, said ring having a friction enhancing external cylindrical surface;
• and
• an insert member comprising a headed screw having a threaded portion threadingly received within said threaded bore portion of said body portion and a separately formed tapered portion for engaging with said smooth bore portion of said body portion;
• said separately formed tapered portion comprising a frustoconical member with a threaded bore therethrough for engaging with said threaded portion of said insert member;
• said insert member having a driving recess in an end thereof opposite said threaded portion for receiving a driving tool and for transmitting torque at a level above 450 inch pounds;
• and
• said tapered portion and said enlarged portion being sized to cause said smooth portion of said bore to expand upon threaded insertion of said insert into said body portion, thereby providing a seal between said body portion and said tube.