32 Fatigue Crack Growth, Fatigue, and Stress Corrosion Crack Growth: Section XI Evaluation

Fatigue has often been described as the most common cause of failure in engineering structures, and designers of pressure vessels and piping have incorporated fatigue considerations into design requirements since the first edition of Section III in 1963. The development of this technology and its application in Section III are discussed in Chapter 39 of the third edition of this publication. Its application in Section XI is discussed in Section 32.3 of this chapter.

With the advancement of the state of the art, the ability to recognize how the growth and size of a crack can lead to failure has been enhanced. This technology has been a key aspect of the Section XI flaw evaluation procedures since the 1974 edition was published and will be discussed thoroughly herein.

Further advancements in the state-of-the-art in fracture evaluation resulted in the introduction of models for stress corrosion cracking into Section XI in 2001, and since that time additional models have been added and more are planned. This addition gives Section XI flaw evaluations a complete treatment of all the potential modes of cracking that can occur in components, and details will be provided in Section 32.2.