An Improved Fixture to Quantify Corrosion in Bolted Flanged Gasketed Joints Subjected to Service Conditions

Abstract

This study concentrates on the corrosion behavior of bolted flanged gasketed joint systems. A novel fixture is proposed to quantify the corrosion between gaskets and flanges under services conditions. According to the literature, due to the presence of crevices and potential differences between gaskets and flanges, corrosion widely occurs in such joints. Crevice corrosion and galvanic corrosion can create paths to leakage of the pressurized fluid and may cause catastrophic failure. Corrosion in bolted gasketed joints was investigated previously; however, the effects of the operating conditions were not reported. Operating conditions include fluid flow, pressure, pH, conductivity, temperature, and gasket contact pressure. The first step of this research study is to introduce a new experimental setup to examine the corrosion behavior of bolted flanged gasketed joints. The developed setup is a fixture that consists of a pressurized bolted gasketed joint that enables real-time monitoring and recording of the corrosion parameters under the influence of service conditions. In the second step, potentiodynamic polarization test is carried out (according to ASTM G5) to measure the corrosion rate and obtain more details on the corrosion behavior of a pair flange and gasket materials. These tests are conducted using the novel designed setup that reproduce the behavior of industrial bolted flanged gasketed joint systems. It consists of a working electrode (flange material), a reference electrode (Ag/AgCl), and an auxiliary electrode (a stainless-steel rod). Three types of graphite gaskets are considered for electrochemical tests. The 0.6 M NaCl solution is used for the corrosion tests. After each test, the corroded surfaces of the specimens are examined via confocal laser microscopy to visualize the morphology of the damaged zones on the surface and localize corrosion, respectively.