Detection and characterization of stress corrosion cracking and hydrogen-induced cracking in carbon steel piping and vessels

Saudi Aramco has many thousands of kilometers of carbon steel cross-country pipelines, in- plant piping, and hundreds of process vessels that may experience environmental conditions favorable for the formation of several different types of cracking. Two types of cracking of particular interest to the company's engineering and production personnel are caustic stress corrosion cracking propagating from the inside to outside of process piping walls and hydrogen induced cracking (HIC) in piping and vessel walls. The occurrence of these cracks in operating piping and large vessels, when undetected, may present problems due to potential failures during operation of systems and facilities. Once the location of cracking is known, the extent and severity of the problem can usually be determined using suitable nondestructive examination (NDE) techniques. Screening methods offering accurate detection and location of cracking and capable of 100% inspection of a given piping system or vessel need to be developed. Examples of how the two types of cracking are normally located along with details of the nondestructive characterization methods used are presented.