Thread Content
Combined with the previously sorted out background information on the key corrosion areas of the atmospheric and vacuum distillation unit, corrosion testing can be carried out regularly through the following methods to cover key areas of the entire unit.: Fixed-point manual thickness measurement inspection targets the volatile lines at the top, high-temperature side lines, heating furnace tubes and other easily corroded parts. Ultrasonic thickness measurement and pulse eddy current scanning are carried out on a periodic basis. The focus is on detecting stress concentration areas such as welds, elbows and tees, and recording changes in wall thickness to calculate the corrosion rate. Online continuous monitoring deploys a non-invasive online thickness measurement system at high-risk points such as the constant overhead air cooling inlet and four-wax reduction oil line. It is equipped with precision resistance corrosion probes and pH value probes to collect corrosion data in real time and dynamically adjust the detection frequency to achieve maintenance-free continuous monitoring for 3 to 4 years. During the shutdown of the special inspection device for shutdown and overhaul, macro-corrosion morphology inspections were carried out on internal components such as trays, float valves, heat exchanger tube bundles, etc., combined with scale sample composition analysis and metallographic testing, to detect hidden pitting corrosion and stress corrosion cracking hazards, and simultaneously completed the update of the corrosion ledger of the entire device. Sampling of physical and chemical indicators of the medium regularly analyzes the pH value, Cl⁻, and Fe²⁺ concentrations of the constant top-cutting water, as well as the iron ion content of the high-temperature side line oil. The equipment corrosion trend can be indirectly predicted through changes in the medium indicators, and the process anti-corrosion plan can be adjusted in advance.