Equipment corrosion issues in sulfur plants

Handling of decommissioned equipment ㈠ The workshop thoroughly purges the decommissioned equipment to remove residues and moisture. (ii) Isolate the process pipelines connected to the outside world to prevent leaks, spills, cross-contamination, and freezing. Valves connected to the outside world should be fitted with blind flanges and closed; these blind flanges must be labeled as such, and a register should be maintained listing them along with the responsible persons. (III) For facilities connected to the power system, contact the corresponding power department to close the supply and return system valves and install blind flanges. ㈣ Any leakage at valves, flanges, etc. that occurs during the operation of the unit must be addressed immediately to restore them to a proper condition, thereby preventing nitrogen leakage when the unit is shut down and filled with nitrogen. (5) Decommissioned equipment and devices shall be marked with safety and environmental protection labels in accordance with the requirements of the Safety and Environmental Protection Department. Article 39 Protection and management of individual equipment: (1) After the equipment has been in use for a period of time, it is necessary to remove corrosion products (including deposits or sludge), clean it, and dry it after it is taken out of service, so that the equipment is clean and free of water. (ii) Equipment such as towers and containers can be protected by nitrogen filling, and the nitrogen level should be replenished in a timely manner as appropriate. (III) If the shutdown period exceeds six months, the gas-phase corrosion inhibitor protection method can also be employed; this method can be used for towers, containers, and waste heat boilers, with a typical protection duration of 3–4 years. (IV) For air coolers, nitrogen filling can be used for protection. (v) For cold exchange equipment, after removing the core for cleaning and drying, it is immersed in lubricating oil for protection; once removed, it is reinstalled and then protected with nitrogen. (vi) The valves shall be protected by applying grease, covered promptly with thick plastic film, and undergo re-antirust treatment annually. ㈦ The anti-corrosion paint on the outer surface must remain intact. Article 40: Protection Management for Devices and Equipment That Are Not in Use for a Long Time ㈠ Protection of the Inner Surfaces of Equipment 1. For equipment with severe corrosion, use a high-pressure water gun to remove impurities from it first; manually remove any areas on the metal surface where corrosion has caused bulging or rusting, in order to prevent such corrosive substances from interacting with oxygen, water, and other elements and thereby accelerating further corrosion of the equipment. ⒉Drain the water remaining in the equipment’s interior; stopping operation for cleaning can result in water staying inside the equipment. After shutting down, promptly open the drainage outlets at the lowest points of the equipment and pipelines to remove the water, and use air to purge any water that remains in hidden areas along the cleaning path. ⒊For equipment equipped with oil filling for protection, after purging the medium inside the equipment with steam, diesel should be filled in; safety issues such as leaks must be taken into consideration. ⒋For equipment that cannot be filled with oil, nitrogen protection can also be used by introducing nitrogen into the system and maintaining a certain positive pressure to prevent outside air from entering. The purity of nitrogen should be maintained at over 99%, and the nitrogen pressure as well as the integrity of the system should be checked regularly. The general procedure is as follows: first, use steam to purge and completely remove oils with high freezing points; then use industrial air for purging to keep the surfaces of the equipment and pipelines dry; finally, use nitrogen to displace all air from the system (at a pressure of 0.4–0.5 Mpa). After displacement, seal the inlet and outlet with valves or blind flanges, maintaining a nitrogen pressure of around 0.2 Mpa. ⒌Vapor-phase corrosion inhibitors are used to protect other towers and containers within the installation; within these sealed containers, the inhibitors continuously evaporate to release protective gases with high vapor pressures, which form a chemisorbed layer on the metal surface that prevents metal corrosion, thereby achieving long-term protection. Seal it promptly after filling to prevent a large amount of anti-corrosion gas from leaking, which could affect the anti-corrosion effect. It is important to pay attention to the different materials of the equipment, as different preservatives should be selected accordingly. ⒍The water system is used to drain any residual water from the equipment; it is then shut down for cleaning. For equipment that can be filled with oil, an oil-based protection method is employed, while for equipment that cannot be filled with oil, nitrogen protection can be used. (ii) Protection of the outer surface. ⒈The shaft shoulders of mechanical pumps, the exposed valve stems, and the steel cables of lifting equipment should be lubricated once a year. When greasing the valve stem, first ensure the valve is in the fully open position; after greasing the threaded part of the valve stem, then close the valve completely. After lubricating the steel wire rope and valve stem, wrap them promptly with thick plastic film. ⒉The electrical components of outdoor lifting equipment, the valve heads of various other types of valves (such as electronically controlled valves and pneumatically controlled valves), the on-site control panels, the surface-mounted instruments, the machine body, and the associated motors are all covered with thick plastic film. ⒊Based on the condition of corrosion on the outer surface of the equipment and steel components, feasible measures are taken for anti-corrosion treatment. ⒋Critical, precise, and valuable electrical instruments are taken back to the warehouse for secure storage. ⒌The floor, equipment surfaces (or covers), and factory premises are cleaned weekly. Ensure the floor is free of debris, with the equipment surfaces basically free from dust and oil stains; keep the factory premises clean and tidy, arrange items neatly, and recycle waste promptly. Article 41: Provisional shutdown and protection management of equipment ㈠ During shutdown, assist with process and safety operations; if it is not necessary to return the materials, do so as little as possible, and isolate oxygen to protect the equipment and pipelines. (ii) For equipment that can be filled with oil, the oil protection method should be employed: after purging the equipment’s interior with steam, diesel should be poured into it, taking into account safety issues such as leaks. (III) For equipment that cannot be filled with oil, nitrogen protection can also be used by introducing nitrogen into the system and maintaining a certain positive pressure to prevent outside air from entering. (IV) Drain the water remaining in the equipment of the water system, shut it down for cleaning; when a water cooler has been in use for over a year, its core should be removed for cleaning when it is shut down. (v) Inhibiting polythionic acid corrosion: The main methods include selecting appropriate metals, preventing oxygen from entering, performing alkaline cleaning of the surface, and avoiding the formation of liquid water. ㈥ During shutdown of the high-temperature expansion joint, electric heating should be applied to maintain a temperature above the dew point. (vii) Protection of the reactor: After unloading, the reactor should be purged with dry air, and this purging process should continue throughout the time the reactor is open. (Ⅷ) On the inner surface of heating tubes made of austenitic stainless steel and austenitic alloys, if coking is not removed, the tubes must be kept dry ； During decoking, it is necessary to ensure that the surface of the furnace tube is alkali-washed with an alkaline solution. The thermal decoking method should be used such that no condensation occurs on the furnace tube before decoking is completed; when this method is employed, alkali washing should be applied during and after the decoking process. ㈨ Protection for special equipment plate-type air coolers and other air coolers. After purging and neutralization cleaning during the maintenance shutdown, nitrogen protection is applied.

How to use vapor-phase preservatives? What’s the cost?

This post was last edited by Wang Genrong on 2016-5-6 at 19:23. Protective agent for standby devices: Huarong-911. Features: Huarong-911 is an improved version of HL-911 and boasts the following outstanding features: Convenience: When using the Huarong-911 protective agent, there is no need to dry out the device or to conduct regular analyses and inspections; simply drain the medium from the device and apply the agent once. When the protection completion device is in use, the agent can be removed directly or washed away with water. High efficiency: After applying the Huarong-911 protective agent to the equipment that is not in use, no new signs of corrosion or rusting appear on the metal surfaces of the equipment. The protective agent for standby devices can volatilize automatically at room temperature and has a high vapor pressure. The protective agent for standby devices has strong permeability and can remove existing scale layers. The diffusion distance of the protective agent for standby devices can reach over 10 meters, enabling the protection of metal surfaces both at close distances and at greater distances. Safety: Although the protective agent for shut-down equipment has an irritating odor, it is harmless to humans, does not pollute the environment, and causes no environmental damage. Low cost: The Huarong—911 protective agent requires a small amount, is inexpensive, easy to use, offers excellent performance, does not pollute the environment, and is safe to use; its cost is only about 1/10 of that of traditional dry-method protection techniques. The amount of this protective agent to be used is determined based on the actual volume of the device to be protected, at a rate of 1.5 kg/m3 per year. If the surface area of the equipment is large, the amount used can be increased appropriately. Physical and Chemical Properties
Serial Number | Test Item | Specification
1 | Appearance | White crystalline powder
2 | Flammability and explosiveness | Non-flammable and non-explosive
3 | Odor | Pungent odor characteristic of amines
4 | Flash point | 245°C
5 | Acidity/alkalinity | Slightly alkaline
6 | Specific gravity | 1.57 (at 20°C)
7 | LD50 (oral, in mice) | 1130 mg/kg
8 | Corrosion inhibition rate | Greater than 95%

Application Scope
1. Huarong—911, a protective agent for devices during shutdown, can be widely used for corrosion prevention during the shutdown period of various types of devices. 2. The protective agent for Huarong—911 shutdown and standby systems can be widely used for corrosion protection during the shutdown and standby periods of industrial plants in sectors such as chemicals, oil refining, papermaking, pharmaceuticals, and metallurgy. 3. Huarong—911 standby equipment protector can be widely used for the anti-corrosion protection of various types of steel containers, heat exchangers, pipelines, etc., during their standby periods. Usage Method 1: Drain all materials and water from the device. 2. Open the access holes for people and hands; add the medication to the trays at a rate of 1.5 kg/m3. Place the trays inside the equipment in a specific order. Plastic sheets can be used as substitutes for trays, or the medication can simply be spread on the bottom of the drying equipment. Any area where the vapor generated by the medication can reach will thus be protected. 3. Seal the protected system to prevent it from communicating with unprotected systems or the atmosphere. Precautions: 1. The effective protection period of the protective agent is one year. If there is an excessive amount of water remaining in the equipment after drainage, or if it has been out of use for a long period, the amount of protective agent used can be increased by 0.5 to 1 time. Equipment that has been in use for more than three years should be inspected annually, with additional protective agent added as appropriate. 2. This product is harmless to the operation of the equipment; when restarting the equipment, there is no need to remove the substance – simply take out the container holding it. 3. When the equipment contains a small number of copper components, efforts should be made to isolate them or wrap them separately with plastic sheeting. Packaging and storage: This product is packaged in 25kg woven bags, which are lined with plastic liners. Store in a cool, dry place in a sealed container; the effective shelf life is three years.

Using standby device protectants is economical, convenient, and efficient; contact Manager Yang at 13309317532