An Improved Fixture to Quantify Corrosion in Bolted Flanged Gasketed Joints

Abstract

This study discusses the corrosion behavior of bolted flanged gasketed joint systems. A novel fixture is proposed to quantify the corrosion at the gasket–flange interface under service conditions. 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 average gasket contact stress. This study starts by introducing a new experimental setup to examine the corrosion behavior of bolted flanged gasketed joints. The developed fixture consists of a pressurized bolted gasketed joint that enables real-time monitoring and recording of the corrosion parameters under the influence of service conditions. Second, potentiodynamic polarization testing is conducted to measure the corrosion rate and obtain data on the corrosion behavior of a pair of flange and gasket materials. These tests are performed using the novel setup that reproduces 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 compressed in the fixture are subject to electrochemical corrosion tests with a 0.6 M NaCl solution. The morphology of the specimen's corroded surfaces is examined via confocal laser microscopy.