A method for online monitoring of corrosion of a pressure vessel of a gasifier, the method comprising: exposing a portion of a first electrode and a second electrode of a first set of electrodes, and exposing a portion of a first electrode and a second electrode of a second set of electrodes, to a corrosive environment within a pressure vessel due at least in part to corrosive gaseous salts condensing on a wall of said pressure vessel, wherein said first electrode and said second electrode of each set of electrodes are disposed in a wall of said pressure vessel and isolated from each other by an insulating material, said first and second electrodes being electrically coupled such that when an electrical potential difference exists between said first electrode and said second electrode an electrical current flows between said first electrode and said second electrode, the electrical potential difference between said first electrode and said second electrode being based at least in part on corrosion at said first electrode or said second electrode; wherein the first set of electrodes is formed from the same material as the pressure vessel, and the second set of electrodes is formed from the same material as a different component; measuring at least one of the electrical potential difference and the electrical current flowing between said first electrode and said second electrode of each set of electrodes; analyzing the at least one of the measured electrical potential difference and the measured electrical current to predict the corrosion characteristics of said pressure vessel and said different component; determining when to perform a corrective action on said pressure vessel based on the predicted corrosion characteristics; combining the measurements of the at least one of said electrical potential difference and said electrical current with other available data, such as pressure vessel operating hours and operating temperatures, to predict the operating life of the pressure vessel; and performing the corrective action on said pressure vessel. exposing a portion of a first electrode and a second electrode of a first set of electrodes, and exposing a portion of a first electrode and a second electrode of a second set of electrodes, to a corrosive environment within a pressure vessel due at least in part to corrosive gaseous salts condensing on a wall of said pressure vessel, wherein said first electrode and said second electrode of each set of electrodes are disposed in a wall of said pressure vessel and isolated from each other by an insulating material, said first and second electrodes being electrically coupled such that when an electrical potential difference exists between said first electrode and said second electrode an electrical current flows between said first electrode and said second electrode, the electrical potential difference between said first electrode and said second electrode being based at least in part on corrosion at said first electrode or said second electrode; wherein the first set of electrodes is formed from the same material as the pressure vessel, and the second set of electrodes is formed from the same material as a different component; measuring at least one of the electrical potential difference and the electrical current flowing between said first electrode and said second electrode of each set of electrodes; analyzing the at least one of the measured electrical potential difference and the measured electrical current to predict the corrosion characteristics of said pressure vessel and said different component; determining when to perform a corrective action on said pressure vessel based on the predicted corrosion characteristics; combining the measurements of the at least one of said electrical potential difference and said electrical current with other available data, such as pressure vessel operating hours and operating temperatures, to predict the operating life of the pressure vessel; and performing the corrective action on said pressure vessel.