99 Diseases of Pressure Equipment: Casting Defects

Casting defects are an age old problem for our industry that seems to be getting worse as foundries in the older industrialized world shutdown for economic reasons. As this process continues, more and more of our valve, pump and fitting castings are starting to come from foundries that do not seem to have the same QA/QC of the older ones, resulting in badly defective castings, especially with some of the higher alloy and more complex castings that are more difficult to cast. These castings then can make their way into our operating facilities unless we take the adequate precautions to eliminate them. Those steps include specifying the casting quality (e.g. ASTM standards) and an appropriate amount of NDE (including RT) and pressure testing to validate casting quality. Witnessing a certain amount of API 598 valve testing can also improve the quality of received valves. Additionally, be aware that the same issues covered above on repair welds can apply to repair welds on castings; especially if you are unaware that the foundry or fabricator is trying to salvage a defective casting by covering up porosity and shrinkage cracking with a big glob of weld metal. Some companies are starting to add specific higher-quality foundries to their “approved supplier” lists, as well as starting to hold valve suppliers (in addition to manufacturers) responsible for the quality of the products they handle. The really interesting “gotcha” in this scenario is that those companies that insist on higher quality castings with their specs and QA/QC usually get them, while the rejected castings go back into the pool to be supplied to other companies that are not paying that much attention to casting quality.

Are you getting someone else’s rejected castings in your valves and pump cases?