This paper is inspired by a series of failures that occurred in steam drums and deareators in power generation and chemical/petrochemical plants. In every case the failure occurred in non-Post Weld Heat Treated (PWHT) carbon steel (CS) welded joints and was related to the synergic action of the mechanical stresses and the chemical environment (boiler and feed water). Nevertheless technical literature has already covered and discussed the topic and the damage was experienced for a long a time by Users the primary mechanism and root causes of the failure events are still unclear.The paper shows an overview of different case histories and failure investigations related to in-service cracking of non-PWHT CS welded joints in deareator and steam drum. The damage was associated to a sort of Stress Assisted Cracking (SAC) related to static and/or dynamic stresses and corrosive potential of water (mainly oxygen and pH).The feedback of the failure investigations has been a starting point for a detailed design and fabrication review involving design material selection welding process selection post weld treatments (physical and thermal) and Non Destructive Examinations (NDT).