Manifold failure in service but why?

摘要

Engineers from one of TWI's Industrial Members delivered the remains of a welded manifold valve to TWI's defect characterisation and interpretation experts. They needed to know the reason the component cracked. The valve was a substantial forging made from F22 alloy steel. A central hole had been machined around which a stub had been welded. Cracking occurred at the toe of this weld.