Abstract
Stress corrosion cracking of stainless steels is a well known corrosion mode encountered in a number of industrial processes. It is the case in the chemical process industry but also in a number of other industries such as oil and gas in refineries and production facilities. Stress corrosion cracking can either occur externally often under insulation but also on free exposed surfaces, or internally in process fluids or cooling circuits where chlorides are present intentionally or not. When there is an accidental ingress of chlorides in a circuit, it is generally too late when cracks are detected as they are already through wall. In this case however the same question always arises: if chlorides are removed from the circuit and the leaking component is repaired, will the cracks already present in the installation stop propagating? When chlorides cannot be removed, is it possible to slow down or even stop the propagation of these cracks by injecting an inhibitor in the fluid? In order to address these two questions, laboratory tests have been conducted on a 316L stainless steel small diameter pipe in a hot concentrated chloride environment. Acoustic emission has been used to monitor the cracks and establish if and when they propagated and stopped. The results show that stress corrosion cracking requires the presence of chlorides in the bulk liquid environment to keep propagating. Inhibition of existing stress corrosion cracks can be performed provided the concentration of inhibitor is sufficient.
