Fitness-for-Service Assessment of an Injection Point in a Boiler Feed-Water Line Subjected to Corrosion

When inspecting a piping system, injection points should receive specific attention because they are sometimes subject to accelerated or localized corrosion. If metal loss is found at the location of such injection points during the inspection, a Fitness-For-Service (FFS) assessment can be used to evaluate whether the component can continue to operate safely without a plant shutdown. A more practical method for assessing the integrity is needed to provide specific procedures for the FFS assessment of a piping branch, e.g., an area-replacement rule. This paper will present a practical example of an FFS assessment of an injection point in a boiler feed-water line in which internal corrosion was found using ultrasonic testing. We outline a way to characterize the metal-loss shape and assess the integrity of the injection point. We also present a quill-type injection design as a permanent countermeasure.