Application of adequate corrosion control technique to achieve the necessary safety and desired life of offshore process facilities are considered primarily tasks of operators and authorities. The paper will describe primarily tasks of operators and authorities. The paper will describe different types of corrosion hazards and consequences of a corrosion failure for the different components of a process system. The following aspects will be considered:
accessibility of components
consequences of a corrosion failure
corrosion types such as CO2-corrosion, H2S-corrosion, erosion corrosion, etc.
corrosion control techniques such as inhibitors, coating, corrosion resistant steels, etc.
corrosion monitoring with special emphasis to procedures for thickness measurements
The work is primarily based on experiences from design evaluation and inspection of equipment which have been in service, but it is also supplemented by laboratory testing of corrosion rates and inhibitors. The so-called "sweet" corrosion which is caused by corrosive gases such as CO2 and chlorides dissolved in the produced water is influenced by a number of parameters which are discussed. The "sour" corrosion type materialized by parameters which are discussed. The "sour" corrosion type materialized by hydrogen induced stress corrosion is caused by H2S and water when unsuitable materials used. Requirements on selection of materials and fabrication procedures and testing methods for application under sour conditions are procedures and testing methods for application under sour conditions are reviewed. The application of corrosion control techniques to achieve the necessary safety and desired life of the equipment are considered primary tasks of both the operators and the authorities and different approaches may be used to achieve this goal.
In a simplified form the main steps in treatment of hydrocarbons offshore are indicated in Figure 1. In addition to the steps shown on Figure 12, different utility systems such as hydraulic system, instrument air, fire water etc, are of importance for the safe operation of the production of hydrocarbons.
The type of equipment being installed on the platforms is similar to equipment installed onshore, for instance in refineries, but the space is more limited. As every square metre offshore is so costly, the equipment is very compact.