The cylinder body and lining of titanium reaction kettle are just like the heart and blood vessels of the equipment. They directly undertake the core chemical reaction process and belong to the parts with the highest value and the most refined maintenance requirements in the whole device.
Though titanium material is known as the king of corrosion resistance, its maintenance is never once and for all. Improper operation and neglected maintenance will still cause damage or even failure to the expensive titanium cylinder body. Focusing on these core components, this paper systematically expounds the key scientific points and practical methods of maintenance. A thorough understanding of titanium material characteristics is the cornerstone of maintenance. Titanium has both excellent performance and inherent fragility. Commercially pure titanium such as TA2 and titanium alloys are extremely stable in oxidizing media like nitric acid and chromic acid due to the dense passive film formed on the surface. However, in anhydrous strong reducing acids including concentrated hydrochloric acid and sulfuric acid, dry chlorine gas or some fluoride media, the passive film may be damaged. The primary principle of maintenance is to be familiar with the compatibility boundary between process media and titanium materials, and firmly avoid inapplicable working conditions. Detailed explanation of core maintenance points. First, prevent mechanical damage to avoid irreversible damage on titanium surface. Titanium features relatively low surface hardness, and scratches are one of the biggest threats. It is forbidden to directly contact the inner wall with any metal tools or steel wool. A special non-metallic tool library should be equipped with PTFE scrapers, wooden or plastic shovels and high-pressure nylon brushes. All tools entering the kettle shall be coated and protected on the contact surface. For feeding and discharging, buffer devices shall be equipped or solid materials shall be dissolved in advance before adding, especially hard particles and catalysts.
When cleaning caked materials, chemical methods such as swelling and heating shall be adopted to soften materials first. During the disassembly and assembly of manholes and hand holes, bolts shall be placed in special containers to prevent falling into the kettle. Torque wrenches shall be used for diagonal and uniform fastening to avoid micro deformation of flange faces.
Second, carry out scientific cleaning to put an end to cross contamination and residual corrosion. Cleaning is not only daily decontamination, but also anti-corrosion pretreatment. Adhere to the graded cleaning procedure. Complete immediate flushing while materials are still hot after reaction, so as to prevent materials from caking after cooling. Select targeted cleaning agents for chemical cleaning according to residue properties. Hot alkali solution can be used to treat organic matters, and dilute nitric acid or citric acid is applicable to inorganic scale. It is strictly prohibited to use hydrofluoric acid, concentrated hydrochloric acid, phosphoric acid and other acids that can corrode titanium. Conduct final rinsing with high-purity deionized water until the liquid is neutral and the conductivity reaches the standard, so as to eliminate ion residual. Verify the cleaning quality through white cloth wiping, endoscope observation and water quality index detection. Third, implement systematic inspection to eliminate potential hazards in the early stage. Establish a hierarchical inspection system combining macroscopic observation and microscopic testing. Operators shall conduct visual inspection before and after each kettle opening in daily patrol, and record abnormal changes of inner wall luster and color. Conduct in-depth inspection on a regular basis every quarter or after the production of key products.
Check the inner wall, welds and transition areas for scratches, pits, cracks and tarnishing under sufficient light. Use industrial endoscopes to inspect dead corners that are difficult to observe directly. Arrange regular non-destructive testing every year or during major maintenance, so as to detect surface micro cracks and internal welding defects. Fourth, standardize temperature and pressure control to prevent thermal stress and fatigue damage. Titanium is sensitive to thermal shock due to its different linear expansion coefficient from steel jacket. Strictly control the heating and cooling rate, and the temperature change speed shall not exceed the specified range. Ensure the full circulation of heat conduction medium to prevent local overheating and dry burning. For production with frequent pressure changes, record pressure circulation times to prevent equipment fatigue failure. Professional decision making for damage repair. In case of equipment damage, scientific evaluation and standardized repair must be carried out.
Slight scratches and shallow pitting with tiny depth can be polished to restore surface finish and regenerate passive film on the premise of no impact on structural strength. Deep damage and cracks shall not be repaired by welding without professional qualification. Titanium welding must be completed under strict argon protection by certified personnel. For large area corrosion and serious structural damage, contact the manufacturer and professional institutions for safety assessment, and formulate schemes of local repair or overall replacement. Establish complete maintenance files and form preventive management awareness.
Set up a lifelong electronic maintenance file for each titanium reaction kettle, and record detailed information including medium parameters of each reaction, cleaning schemes and verification results, daily inspection data, non-destructive testing reports and all repair records. The maintenance of cylinder body and lining of titanium reaction kettle is a systematic work integrating material science, chemical technology and refined equipment management.
Its core lies in prevention priority, inspection as the key, standardized operation and professional maintenance. Turning passive maintenance work into active management measures to ensure production safety, product quality and economic benefits can fully protect the titanium reaction kettle, and maintain its long-term stable operation in harsh chemical working conditions.
