Technical exchange on glass-lined equipment

The manufacturing of glass-lined equipment is crucial, while inspection is of key importance. We can discuss the manufacturing processes of various glass-lined equipment as well as the production of linings; inspections of glass-lined containers can also be talked about! I have a handout on glass-lined equipment; I’ll upload it another day – the internet speed isn’t very fast today!

Looking forward to the poster uploading it; my company has many enamel reaction kettles, and we need to learn about* and gain knowledge related to them.

Basic Knowledge of Enameled Equipment I. Properties of Enameled Products Enameled equipment is created by spraying a glassy glaze with a high silicon content onto the surface of steel plates, followed by multiple high-temperature firing processes at 920°C to 960°C, which enables the glassy glaze to adhere tightly to the surface of the metal substrate. The properties of enamel are as follows: 1. Corrosion resistance: It can resist organic acids, inorganic acids, organic solvents, and alkaline solutions with a pH value of 12 or less ； However, it is not applicable to strong bases, HF, as well as phosphoric acid at temperatures above 180°C and concentrations above 30% ； 2. Non-stick property: The smooth glass surface does not stick to the medium and is easy to clean ； 3. Insulation: Suitable for applications where static electricity is likely to be generated during the medium transfer process ； 4. Isolation: The glass layer separates the medium from the container’s steel frame, preventing iron ions from dissolving into the medium ； 5. Freshness retention: The glass layer provides good freshness retention for the medium. II. Operating conditions for enamel equipment: The enamel layer can resist most inorganic acids, organic acids, organic solvents, and other substances; it exhibits excellent corrosion resistance, especially in media such as hydrochloric acid, nitric acid, and aqua regia. But it cannot be used under the following conditions: 1. HF at any concentration and any temperature cannot resist corrosion ； 2. Phosphoric acid: Corrosion is severe at concentrations of over 30% and temperatures above 180°C ； 3. Hydrochloric acid: At a concentration of 10–20% and a temperature above 150°C, it causes severe corrosion ； 4. Sulfuric acid: At a concentration of 10–30%, it cannot resist corrosion when the temperature is above 200°C ； 5. Alkaline solutions: It cannot resist corrosion when the pH is 12 or higher and the temperature is above 100°C. III. Use of chemical enamel equipment: Although the mechanical strength of chemical enamel equipment is much better than that of glass and ceramic equipment, enamel is ultimately a composite material formed from a glass-ceramic matrix and metal; therefore, it still has the same weaknesses as glass and ceramics, namely an inability to withstand bumps, impacts, and shocks. The difference between them is that enamel equipment has a metal casing; when the glaze layer is damaged, it does not lose its usability immediately like glass or ceramic equipment. Instead, it takes some time for the damage to become apparent (the length of this time depends on the environmental conditions) before it loses its usability. From a positive perspective, this feature provides users with a sense of security; from a negative perspective, however, it is precisely this sense of security that can lead many careless users to form misconceptions and thus ignore the conditions for safe use. Attention must be paid to this. Proper use of enamel equipment can **increase its lifespan. Proper use involves selecting enamel products of good quality, with appropriate specifications and types based on the conditions of use, as well as strictly adhering to all safety procedures. IV. Precautions for Transportation and Installation 1. Handling: When moving enamel equipment, try to keep it in its original packaging as much as possible. When moving unpackaged equipment, be careful to ensure that only the lifting rings, lugs, and feet on the equipment bear the load. Move gently to avoid collisions and vibrations ； 2. Lifting: When lifting, in addition to following the precautions required for handling, special care must be taken to avoid collisions. When working in an environment prone to collisions, more than three positioning control measures must be adopted to ensure stable lifting ； 3. Equipment inspection before and after installation: Enameled equipment should have its enamel surface inspected both before and after installation. Equipment with damaged porcelain surfaces must be properly treated before it can be used; otherwise, it should not be installed. The methods for checking the porcelain surface include using a high-frequency spark generator for inspection, as well as shining a 60-watt safety lamp to check for any signs of chipping or cracking. Note: When using an electric spark generator for detection, the voltage applied is generally specified to be controlled at 5000 volts. When it is necessary to increase the detection voltage for critical equipment, approval from the manufacturer must be obtained ； 4. Selection and treatment of gaskets: Gaskets should be selected based on the reaction medium, concentration, and temperature. Before use, necessary treatment must be carried out according to the properties of the selected padding. For example, when using asbestos gaskets, they should first be soaked in boiling water until they become soft; otherwise, it will be difficult to compress them ； The gaskets currently available for selection include asbestos rubber and rubber coated with polytetrafluoroethylene. 5. Installation and connection of flanges: The connection between enamel-coated equipment and external pipelines is achieved through flanges; hence, there are many flanges, and special attention must be paid during installation. Often, poor flange installation leads to porcelain cracking or leakage, resulting in internal corrosion or corrosion from the outside in. When installing flanges, the following rules must be followed: the end faces of the flanges that are to be joined together (such as the flanged surfaces in the case of flanges with flanged collars) must be parallel. When tightening the bolts, it is important to apply force evenly and symmetrically; avoid tightening them unevenly. The method is to tighten all the bolts gradually, in diagonal pairs, alternating back and forth ； 6. Installation of clamps: The number of clamps specified for enamel-coated equipment is determined through scientific calculations, taking into account both safety and sealing requirements. Therefore, it is essential to ensure that the correct number of clips are in place during installation; if any are missing or damaged, they must be supplemented or replaced. When tightening the clamps, it is also necessary to follow the rules for tightening flange bolts ； 7. Installation of the mixer and reducer: The installation of the enamel-coated mixer and reducer is first carried out on the bracket along with the tank lid. To protect the porcelain layer, a rubber sheet must be placed between the tank lid flange and the support. Debug to check if it is installed properly. The installed mixer and reducer should be in the correct orientation; the mixer should have anti-loosening measures in place, it should rotate smoothly without any obstacles, and it should operate properly once powered on. Once installed, it can be assembled with the tank body ； 8. Welding on enamel equipment: Note that, generally, welding is not allowed on the outer wall of enamel equipment where an enamel layer is present. When welding on a jacket without a porcelain layer, it is necessary to take measures to protect the porcelain-coated steel plate; the area adjacent to the weld site must not become overheated. The protective measures include avoiding the use of oxygen for cutting or welding, and ensuring that water flows inside the jacket during cutting. When the weld site is near the upper and lower connection rings, the inner porcelain surface must be preheated evenly, and welding should be carried out using intermittent welding techniques ； 9. Piping for enamel equipment: Care should be taken to ensure accurate dimension calculations when piping. The positions of the external pipes and fittings must be secured only after proper installation. Note that components with a porcelain coating must not be subjected to any external forces other than their own weight; otherwise, excessive strain stress may cause the porcelain coating to crack. For overhead glass-lined pipes, a support should be installed every 2 meters or so ； 10. Protection of the enamel layer: When carrying out construction and welding work near enamel-coated equipment, it is necessary to cover the tank opening to prevent foreign objects or welding slag from damaging the enamel layer. When entering the tank for inspection or repairs, it is important to place a soft and clean mat on the bottom of the tank. V. Precautions for Use 1. Feeding: Be cautious when feeding. No hard objects should fall into the enamel-lined containers, and it is also necessary to avoid heating materials in empty containers or cooling materials in hot containers; the temperature difference used should not exceed the specifications set by the equipment’s technical requirements. When adding materials into the equipment, care must be taken to prevent the inclusion of lumped metal or foreign objects; large, hard materials should be crushed before being added. Minimize the temperature difference between the material and the tank walls, avoiding heating material in a cold tank or cooling material in a hot tank ； 2. Operation: When using equipment with a jacket, pressure and temperature should be increased gradually. First, introduce a pressure of 0.1 MP and maintain it for 15 minutes; then slowly introduce steam until the operating pressure is reached. If conditions permit, an appropriate heating and cooling curve can be determined based on the specific circumstances of the facility, with the rate of temperature change generally kept below 3°C/min. While the equipment is in operation, pay attention to the sealing condition of flanges, joints, manholes, and packing boxes; if any leakage is detected, immediate action should be taken ； 3. Discharging: When discharging, if the bottom of the tank is blocked, do not use metal tools to pry it open; instead, use a bamboo pole, plastic rod, or wooden stick to gently push it aside. When cooling is required after the reaction is complete, it is necessary to wait until the temperature inside the tank drops to a certain level before introducing cooling water into the jacket, to prevent sudden cooling. Under the alternating action of acids and bases, the service life of non-alkali-resistant enamel equipment **shortens**, so it is important to choose enamel equipment with better alkali resistance. Acid-resistant enamel should be avoided in environments with alternating acid and alkali conditions. When discharging the material, if any enamel debris is found, the tank should be opened immediately for inspection; the porcelain surface must be repaired before it can be used again. VI. Maintenance of enamel equipment 1. Regular inspections are necessary; if any damage such as cracks or chipped enamel is detected, it must be repaired promptly before the equipment can be used again ； 2. It should be cleaned regularly to prevent dirt from corroding the surface of the equipment, and the protective paint should be applied periodically ； 3. Hydrochloric acid must never be used for cleaning the jacket; the introduction of hydrochloric acid into the jacket can cause \"scale explosion\" on the inner wall of the tank. Metal tools should not be used to remove adherents from the ceramic surface ； 4. Proper storage is necessary; for all enamel devices that are not in use or only temporarily unused, it is important to take care of them and store them properly to prevent damage from impacts or rain. Make sure that no water gets into the jackets or thermometer casings, as freezing water in winter can cause the enamel layer to crack ； 5. The medium used for heating or cooling in the jacket must be neutral and must not contain any acids; otherwise, \"hydrogen bubbling\" can cause scaling and cracking of the glass lining ； 6. If a descaling agent is used to remove scale from the jacket, this process should be completed in as short a time as possible, followed by repeated rinsing of the jacket; the remaining liquid should be neutral in pH ； 7. Regularly inspect the enamel-covered areas and moving parts. Check whether the sealing condition is normal; if any abnormalities are detected, they should be addressed promptly without delay ； 8. Regularly replace the lubricant in the transmission mechanism and mechanical seal chamber to ensure proper lubrication of all moving parts ； 9. Pay close attention to whether the pressure gauge is sensitive. If it is found that the readings of the pressure gauge system are inaccurate, transformer oil should be added promptly, and adjustments should be made by referring to a standard pressure gauge ； 10. The operating temperature range of enamel-lined equipment at the design pressure is 0–200°C; if the equipment is used at atmospheric pressure, this range can be extended to –20–200°C℃ ； For enamel-lined equipment with jackets, a vacuum is permitted inside the tank, but the pressure difference between the inside and outside must comply with the specified requirements ； 11. The winged thermometer sleeve in the FK series reaction vessels can be adjusted to a range of 0–90°C depending on process requirements. It can be adjusted at any angle within the range to obtain different resistances. It is best to adjust the angle when the machine is shut down. If adjustment must be done during operation, check in advance whether the retaining ring is securely connected to avoid accidents ； 12. For reaction tanks equipped with mechanical seals, when the operating temperature exceeds 70°C, and for those equipped with packing seals, when the operating temperature exceeds 100°C, cooling water should be circulated in the coolers and the jackets of the packing boxes respectively, in order to prevent damage to the sealing elements ； 13. The lubricant (sealing fluid) in the mechanical seal chamber must be clean and free of solid particles. For reaction processes that involve sublimation, it is not appropriate to use the mechanical seal device 14 equipped on this equipment. The metal surface outside the enamel layer must be strictly protected from contact with acids and acidic substances, in order to prevent hydrogen from being generated as a result of reactions between the metal surface and the acids, which could lead to the cracking of the enamel layer. If acid leaks occur, they must be cleaned up and the leak sealed immediately. VII. Summary of Years of Maintenance 1. Early Detection of Damage to Chemical Enameled Equipment It is said that there are devices abroad for early detection of damage to enameled equipment, which can identify sudden cracking of the enamel in such equipment while it is in operation. In fact, this device is not difficult to make. By utilizing the changes in the electrical current between the material inside the enamel kettle and its outer wall (the current is low when the enamel has not cracked and higher after it cracks), an alarm device can be installed; having a professional handle this task should not present any major problems. 2. Precautions for chemical industry enamel equipment: (1) When discharging material during use, if enamel fragments are detected, the equipment should be stopped immediately; a thorough inspection of the equipment should be carried out to determine the cause of the damage, and remedial actions should be taken promptly. (2) Glass-lined equipment should be inspected regularly to detect any minor cracking that may occur promptly. (3) Precautions for using chemical enamel equipment: a. When installing the kettle lid and stirring, be careful to avoid direct collisions ； b. The kettle cover, feed inlet, and discharge outlet should be fitted with bolts tightened symmetrically in accordance with the specifications ； c. For inspections of the lower furnace, a wooden ladder and rubber boots are required ； d. Regularly check the condition of the mixing lock nut to prevent damage to it, which could lead to the reducer reversing and causing the mixer to fall off ； e. When installing flanges and switch manhole covers, nothing should fall downward ； f. When working with enamel-lined tanks or welding on them, the enamel surface must be protected; slag must under no circumstances fall on it ； g. Do not add material to the enamel-lined pot while it is still warm, to prevent the enamel surface from cracking due to sudden cooling ； h. When steam is used for heating the jacket, it must be done in accordance with regulations – overheating is not allowed ； i. If the steam temperature rises or there is a leak in the steam valve, the water inside the jacket must be drained completely. Otherwise, it may lead to a large temperature difference between the upper and lower parts of the reaction tank, resulting in high residual stresses; these stresses can cause the enamel on the parts with lower temperatures to crack and lead to widespread enamel failure ； j. Choose corrosion-resistant gaskets to prevent material leakage and corrosion of the enamel ； k. There are crystals in the pot; it is absolutely forbidden to use iron rods or hammers to break them ； Material should not be added along the wall of the reactor.

Generally, the capacity is below 25 cubic meters; 75 cubic meters is too large. May I ask which company manufactures it?

DE Dietrich from France (Zinswiller) or Pfaudler from America (product made in England)

Thank you. Due to the low level, otherwise I would definitely give you more points

Give me an email address; I can’t upload it, it’s frustrating!

Many thanks to kly907@163.com. This post was last edited by kly907 on 2008-10-13 at 11:28.]

juventus_j1897@sina.com