AGING IVESTIGATION OF METALS OF THE PIPES IN LITHUANIAN POWER STATION

摘要

In order to supply hot steam in the thermal powerstations from heat-exchanger to turbine, long pipes areused. Therefore, the efficiency of such pipeline depends onthe load, temperature and aggressive influence of hydrogenfrom the supplied hot steam. The technological parametersof the supplied hot steam are very high: temperaturereaches up to 570°C, the working pressure of ?219 pipewhen thickness of the wall is 28.5 mm – 13.2 MPa and theworking pressure of ?245 pipe when thickness of the wallis 45 mm – 25.4 MPa. These pipelines can be damaged bytemperature, tension strengths, own weight (including iso-lation) and vibrations caused by the changes in vapourpressure and dynamic loads from unbalanced rotors ofpumps [1-6]. Walls of the pipes are mechanically treatedduring manufacture and the pressure results in thicknessdecreasing of the wall. Thus the state of residual tensionstrengths initiates the cracks. This is the reason, why spe-cial attention is paid to the residual tension strengths,which appear during manufacture of thick-walled pipes.