Solvent-based acrylic carbon paint anodes were installed on the north approach spans of the Yaquina Bay Bridge (Newport OR) in 1985 and performed well after 15 years. Anodes were inexpensive and repairs easy. Depolarization potentials are consistently above 100 with long-term current densities around 2 mA/m 2. Bond strength remains adequate.
Galvele introduced a new framework for localized corrosion with his seminal paper on acidification and chloride accumulation in pits & the need for a critical product of current density & pit depth to sustain this chemistry. This paper is to review the progress in these areas with a particular focus on repassivation potential.
Hydrogen Induced Cracking (HIC) can be a major issue for line pipe exposed to sour environments. In this study, influence of the test solutions on HIC evaluation was investigated from the view point of corrosion. Electrochemical measurements were employed to compare corrosion behavior of line pipe steels between the 0.93N acetate buffer solution and the conventional 0.05N acetate solution.
Over 5 years, 70 to 80 FGD scrubber units have exhibited corrosion problems. Many were after only a few months of service. This paper will provide an overview of readily available technical information in the published literature and past experience that could have been used to minimize corrosion problems in these FGD units.
The work is mainly focused on the corrosion mechanism at low pH (>4) and the order of which the discontinuous and continuous intermetallic phases dissolve. Compositions of each phase, and the area ratio between intermetallic phases and the alpha matrix have been calculated as an average of 20 measurements.
Methodology to simulate actual oil and gas field condition in laboratory tests. A sulfide stress cracking test is carried out on 13% Cr stainless steel with various buffer solutions. Then, pH behavior was estimated. A suitable composition of the solution is proposed by using thermodynamic calculations.
Boiler system is one of the most critical systems for a utility plant. A utility plant had experienced high percentages of boiler downtime owing to boiler tube sheet cracking failures. Investigations carried out revealed high stress at the tube-to-tube sheet joint in the boiler fire-side entrance. Tube-to-tube sheet joints at the boiler fire-side entrance had been fabricated by strength welding and without any expansion. The strength welded joint had created undue stress leading to cracking of the weld joint by thermal expansion. A higher quality expanded joint consisting of expanding, flaring and seal welding the fire-side entrance was implemented during the re-tube process. The utility plant has now zero downtime due to boiler tube failure. This article summarizes the description and history of failures with the boiler at the utility plant; investigations and corrective actions carried out; and the present improved condition of the boilers.