Study on design pressure of in-service welding pipes

Abstract

A method of predicting design pressure and burn-through of in-service welding pipes was established. Temperature distributions of in-service welding under variable parameters were simulated by FEM. The effect of flowing of internal media was regarded as forced convection. Based on the numerical results, design pressure of the pipe can be obtained and burn-through can be predicted. It can be concluded that the design pressure decreases with the increasing of heat input. RSF and design pressure of the pipe increase with the increasing of flow rate. There is a range in which the increase changes greatly. For in-service welding, the range should be considered adequately to determine operating condition optimally. RSF increases with the increasing of pipe wall thickness. While the thickness increases to an extent, RSF shows little increase. According to the curves of design pressure versus different parameters, safe working pressure can be achieved.

Experimentação e Simulação Tridimensional de Tubos AISI 304l Via Processo TIG em Operação em Regime Laminar Usando o Método dos Volumes Finitos

“…Thus, it is necessary to consider the influence of the characteristics of the internal flow on the safety of welding in operation. Xue et al [11] suggests that if the fluid has low viscosity and convection is forced, the number of Nusselt (Nu) can be calculated by Equation 5: in which Pr is the Prandtl number, h [W.m -2 . K -1 ] is the coefficient of forced convection and k f [W.m -1 .K -1 ] is the thermal conductivity of the fluid.…”

“…A new mathematical description of the heat source for welding with manual coated electrode was introduced into his work, but limited data were provided for the temperature profiles. Xue et al [11] established a method to predict the rupture pressure and strain in operation under variable parameters using FEM. It has been shown that the rupture pressure of the project decreases when amount of heat input increases.…”