Introduction The Wet Steam Generator used in enhanced oil recovery is a forced circulation once through design. It is also known by many other common names such as thermal recovery heater@ oil field heater@ etc. The once through design enables the use of water essentially free for hardness and suspended solids@ but of relatively high total dissolved solids. The equipment normally uses a fixed water flow system with some modulation capabilities for reduced output. The equipment does not contain drums or level controls@ which are normally associated with stationary boilers. The Wet Steam Generator can be designed for installation in environments found in oil production areas of the world. Minimum operator attention is required. For the most common sizes of Wet Steam Generators@ field construction is held to a minimum. Most units are skid mounted and can be transported by rail@ truck@ or ship. The Wet Steam Generator is equipped with necessary controls and instrumentation to monitor operating pressures@ flows@ temperatures@ etc.@ to protect personnel and equipment.