Doru Romulus Pascu, Traian Fleşer, Radu Roşu, Horea  Moldovan, Octavian Socolescu

 

 

Abstract

The paper presents the way to evaluate the welded joints quality of the walls-membrane panels within the steamer system of the Boiler no.7 of 420 t live steam/h from CET Halânga. This system worked at high pressure and temperature about 5,000 hours and after, the steamer was preserved in nitrogen for 20 years. The chemical analysis, the structural examinations and the mechanical tests were been made on the specimens and samples cut from the hot zone (boiler furnace) and from the cold zone (quota 10…22 m) of the steamer. So, the chemical composition of the pipes and of the fillet welded strips, made from 16Mo3 steel, was been determined. The structures in the characteristics zones of the welded joints contain ferrite and pearlite with molybdenum carbides, having the local hardening estimator of maximum 39.84%. The tensile strength had values between 123 and 133 kN, for the panels from the cold zone, and the maximum value of 164 kN, for the panels from the hot zone. The correlation between the structural examinations and mechanical testing results, and the imposed values specified in PT ISCIR CR7/1 – 2003 norm for these products allows to evaluate the quality of the walls-membrane panels, cut from the hot zone and from the cold zone of the steam Boiler no. 7, from CET Halânga. Their structural and mechanical characteristics are very close, reason for what they can be used to repair the steam Boiler no. 4, which works now in CET Halânga.