Unit for the Heat Treatment and Straightening of Tubes Used in the Steam Generators of Nuclear Power Plants

The article shows the necessity of combining the heat treatment of heat-exchanger tubes with their straightening. It describes the principle of operation and the design of a unit developed to heat-treat tubes and straighten tubes in tension. The new unit ensures the formation of the prescribed stress state during heating and cooling, which results in straightening of the tubes and creates compressive residual stresses in them. The presence of those stresses makes heat-exchanger tubes less susceptible to stress-corrosion cracking and lengthens their service life. Results are described from successful tests of the proposed method in the heat treatment of 16 × 1.5 mm heat-exchanger tubes of steel 08Kh18N10T at the Pervouralsk New Pipe Plant.