Method of Peening the Inside of a Small Diameter Tube

Author:  Harman et al.
Source:  US Patent 4,481,802
Doc ID:  1981132
Year of Publication:  1981
Abstract:  
A method for peening a portion of the inside of a small diameter heat exchanger tube by inserting a rotating shaft having a peening strip affixed thereto, orbiting and reciprocating the shaft as it rotates, and maintaining this operation for a predtermined length of time to relieve residual tensile stresses in a portion of a tube installed in a heat exchanger.