Study on the Failure Mechanism of Burn-Through During In-Service Welding on Gas Pipelines

Abstract

We conclude on the governing mechanism of burn-through and identify the area of highest risk for burn-through occurrence due to a specific combination of loading in this area. In order to investigate the mechanism of burn-through during in-service welding, an exploratory study combining both experiments and finite element simulations was presented. Combined with the theory of high-temperature failure, the initial position of burn-through and its mechanism were discussed. The results showed that burn-through was a kind of intergranular brittle rupture happened at the cooling stage of in-service welding. It started from the partially melted zone, and the cracks expanded along the weakened grain boundaries. When the cracks eventually penetrated to the inner wall, burn-through happened.

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

“…As the connection diameter became smaller, the restriction level increased. Qian et al [7] investigated the drilling mechanism during in-service welding through an exploratory study combining numerical experiments and simulations using the finite element method. The results showed that drilling was a type of fragile, intergranular rupture occurred in the cooling stage of in-service welding, starting in the partially melting zone and the cracks expanded along the weakened grain limits.…”