Experimentálne a výpočtové určenie deštrukčných tlakov v potrubiach s koróznym úbytkom hrúbky steny

摘要

Určenie deštrukčného tlaku pre uzatvorené valcové nádoby v analytickom tvare je známe pre ideálne valcovú tlakovú nádobu, pričom napäťovo-deformačná krivka materiálu je aproximovaná bilineárnou závislosťou. p_1=(A/2 - σ_(pt)/3~(1/2))(r_1~2/r_3~2 - 1) - A.ln r_t/r_3 (kritérium H-M-H) 1.1 P_1=1/2(A-σ_(pt))(r_1~2/r_3~2 - 1)-Aln r_1/r_3 (kritérium Tresca) 1.2 kde A= 2.σ_K/3~(1/2)(1+h)' σ_k je intenzita napätí na rozhraní elastickej a plastickej oblasti, P_1 (P_3) je vnútorný (vonkajší) tlak, r_1 (r_3) je vnútorný (vonkajší) polomer nádoby, σ_(pt) je medza pevnosti materiálu, h parameter bilineárneho modelu materiálu.%Correct determination of values of the burst pressure in pipes is a clear-cut problem only in the case of ideal straight pipes, since for such cases an analytical solution exists. In actual operation, however, the burst pressure is influenced by the condition of the subsoil, corrosion defects on pipe surface, and other factors that can hardly be quantified. The authors note in their contribution that using semi-empirical relations from the DNV-RP-F101 or ASME B31G standards can yield biased results that distort the actual level of pressure pipes' safety. Experimental measurement of burst pressures and numerical models can help to quantify these biases, and so evaluate the actual operability of pipe 'weakened' by corrosion.