Papers by Author: Traian Fleşer

Abstract: The paper presents research made in order to assure additional conditions, compared to those in the general standard, to brazing rods, in order to guarantee safety for the environment and for the brazed joints, against corrosion and embrittlement, in high risk conditions. Environmental safety is ensured by limiting the amount, at 0.25% in depositions, of dangerous residual elements at: Cd<0.1%; Hg<0.1%; Pb<0.1%; Cr<0.1%; As<0.1%. The safety of structures against corrosion is provided by the alloying level of deposits and by neutralizing the coat’s activity. The structure safety towards the embrittlement of brazed joints is ensured by limiting the content of embrittling elements, namely: Sb+Fe+Bi at a maximum of 0.3% and the content of diffusible hydrogen at maximum 5 cm³/100g raw material and by limiting the coat humidity at maximum 10%. The experiments were performed to ensure the set out requirements by following the selection of raw materials on the input criteria of prohibited chemicals, reducing the water content from the elements that make up the coat and by diminishing it’s hygroscopicity by neutralizing it. Prescribing additional conditions has an effect on manufacturing costs, which requires productivity increase at brazing, diminishing work temperature, increasing the moistening capacity of products, reducing the smoke level, effects pursued by the research.

Abstract: The thermoplastic polymer components are used in new domains and the evaluation of their characteristics in specific conditions represents a new actuality domain. The experimental program realized on polyethylene sample pipes type PE 80, SDR 11 GAS, Æ160x15.5 mm had the objective to present the imperfection noxiousness of the geometric configuration, respectively the different dimensions and to define the influence of those to the safety in exploitation of the transport networks and to the industrial distribution of the fluids under pressure (water, natural gases, etc). A hybrid TT-IRT test method is used, combining the tensile test (TT) and the Infrared Thermography (IRT) method. The temperature distribution of the material is monitored under loading conditions with different rates. The noxiousness of the geometric discontinuity is analyzed by the local losses of resistance following the local heating in the imperfection areas. The results obtained are used in design calculus for the materials quality levels in specified safety conditions for the fluids transport networks.

Abstract: The paper presents an application according the reliability and remining life assessment of the reactor (coxing box) from a petrochemical plant, after failure in welding joint of plated shell from W1.5423 (16Mo5) steel with 25 mm thickness, plated with W1.4002 stainless steel with 3 mm thickness. The reactor failure it has associated with initial flaws from welding process, which have accelerated remaining life exhaustion. The assessment made in two steps. It has used VII section of ASME code specifications and iRiS-Thermo expert system for preliminary remaining life assessment. Concomitantly, it was performed the experimental creep and thermal fatigue testing. The program results have defined creep and thermal fatigue exhaustion and its remaining life at common creep-fatigue action, in condition of safety exploitation. It was emphasized the possibility of use an extra 40,000 hours of rehabilitated reactor in the safety condition of normal parameters.