US PATENT SUBCLASS 29 / 890.036
.~.~ Tube inside tube

Current as of: June, 1999
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29 /   HD   METAL WORKING

592  DF  METHOD OF MECHANICAL MANUFACTURE {54}
890.03  DF  .~ Heat exchanger or boiler making {15}
890.036.~.~ Tube inside tube

DEFINITION

Classification: 29/890.036

Tube inside tube:

(under subclass 890.03) Process wherein the heat exchanger or boiler made has an elongated hollow generally cylindrical structure housed inside a similar structure.