Through-wall leakers in cast valve bodies often can be the end result of undetected defective areas created during the metal casting process. Such failures in service are extremely undesirable for valve manufacturer as well as the end user and in many cases such failures could pose significant health and safety concerns.
This article details the challenging nature of defect detection as related to through-wall leakers in typical cast pressure containing units. A discussion of common casting defects and the limitations of common defect detection methods or nondestructive evaluation (NDE) is provided. Finally, casting process simulation is described and presented as a means of detecting and eliminating the casting defects that commonly lead to the failure of valve castings.