Corrosion cracking of 316L reactors
Thread Content
Longitudinal cracks are present between the welds of the reactor head and skirt, as well as between the head and the cylinder – the distance between these two circumferential welds is about 5 centimeters. The reaction takes place at a temperature of 100°C and under a pressure of 0.3–0.4 Mpa; during the reaction, a 3% sodium hydroxide solution is continuously added. It is an oxidation reaction, with continuous air bubbling taking place as well. Several factors need to be considered: once the alkali concentrates inside the reactor, the high temperature can cause stress corrosion. The industrial water used in the alkaline solution contains high levels of chloride ions, around 60–80 PPM, which leads to chloride-induced corrosion. Additionally, is the presence of oxygen accelerating this chloride-induced corrosion? ? What are the key factors? Please have the experts discuss it
The vertical black lines in the purple area represent cracks; some of them have penetrated, while others have not.
Visually, the surface color of the stainless steel is no longer shiny; it appears to be the color of rust, as if it has been annealed
Anticorrosion treatment must be applied; fiberglass lining is required
It might be due to too high a chloride content, causing intergranular corrosion
Is there a problem with the welding process or the choice of welding materials?
Stress concentration occurs in this area, and the medium is likely to be prone to stress corrosion, leading to stress corrosion cracks.
100 degrees, 4 kgf pressure, 60 cubic units – not suitable for fiberglass reinforcement, I guess
Based on an analysis of the corrosion phenomenon, is it intergranular corrosion or stress corrosion?