【Weekly Topic 2017.3.6】Share your work experience!

I have experienced this during my shifts: 1. Once, there was a leak in the oil and gas pipelines of the reactor; the leaking oil and gas caught fire on their own, just like gas stoves； 2. Another time, gasoline sprayed out from the top of the vent tank; I climbed up despite the gasoline to close the valve ；

1. Oil on the surface of the pump used for transporting refined diesel caught fire (the oil was not removed after maintenance work). 2. Air leakage from the glass panel of the buffer tank at the fresh hydrogen inlet (it had to be replaced during the day; it was a quality issue). 3. The programmable valve used for backwashing got stuck, causing the system to freeze up and preventing gasoline feedstock from entering. 4. Leakage and fire at the flange on the side where the reaction products are discharged. 5. Vibration interlock activated in the compressor; the safety valve of the backup unit wasn’t reinstalled, resulting in an immediate shutdown~~~ There are too many issues~~~ These are just the common ones for now~~~~

When I was working in a factory, during a shutdown for maintenance, a blind plate was installed on one of the valves. Then, during startup, a thorough inspection was not carried out; the blind flange was not removed, which led to pressure buildup in the pipeline, resulting in a flash explosion and a fire. This accident tells us that we must pay close attention to the installation and removal of blind plates.

Another issue is that when the adsorbents in the factory coking, nitrogen is used for regeneration; once the nitrogen quality was substandard, with an excessive oxygen content, which led to an explosion. This accident tells us that we must pay close attention to the oxygen content in nitrogen to prevent explosions.

During work in enclosed spaces such as underground tanks, corrosion prevention workers suffered from oxygen deficiency and suffocation; fortunately, it was detected in time, so no casualties occurred. Reminder 1: Strictly measure the oxygen content. 2 requires forced ventilation; 3 requires the use of a respirator if necessary. 4 Must be under someone’s supervision.

They went to check the rotary granulation machine; it was powered off and not marked with any signs, but it was started up by the person who had just taken over. The machine spun wildly, and afterwards they went after that person and started beating him

During the oil unloading process, as it took place in the early hours of summer, negligence on the part of the staff led to an overflow. A large-scale oil spill in the fire pond of an oil depot is extremely dangerous. Later, emergency measures were taken promptly, which helped to avert a series of safety hazards!

1: The storage tank was filled too quickly; the properties of the substance being received were unknown, which led to deformation of the tank, as well as rapid operation. The newly installed wax tank is a atmospheric pressure tank. During the first time material was fed into it, the valves were opened too quickly, resulting in feeding at a rate that did not conform to the design specifications; a large amount of water vapor was present, and flash vaporization occurred inside the tank, which led to insufficient pressure relief and deformation of the tank ； Reflection: For newly installed equipment, risk assessment should be conducted before it is put into use; it is essential to have a clear understanding of the properties and composition of the materials received, and care must be taken to proceed slowly. 2: Deflation of interconnected storage tanks: There are two methanol storage tanks at atmospheric pressure, which serve as backups for each other; normally, the bottom outlets of these two tanks are isolated by DN800 two-position shut-off valves. One day, after a liquid discharge operation, one of the storage tanks became empty. At night, the isolation valve failed, and methanol from the tank that was at full capacity flowed into the empty tank within three minutes, resulting in the tank that was at full capacity collapsing ； Reflection: For the isolation of large methanol storage tanks, it is strictly prohibited to use electric or pneumatic valves; manual valves must be used for isolation, and a nitrogen seal must be in place to ensure proper operation of the self-acting control valve for the nitrogen seal. Avoid three-in-a-row incidents; Incident of fire in the PSA exhaust pipeline for hydrogen recovery: Welding work was carried out at an angle above, 5 meters away from the exhaust pipeline. There was wind on that day, and the welding slag drifted over the check valve at the exhaust outlet, causing the valve cover of the DN500 exhaust pipeline outlet valve as well as the cover of the shut-off valve to catch fire. Five personnel worked together, spraying fire extinguishers at the valve cover, including two portable extinguishers; the fire kept reigniting during attempts to put it out. Only after shutting down the PSA unit and releasing pressure was the fire extinguished ； Reflection: In the event of a fire in a gas pipeline under pressure, don’t panic. It’s similar to a gas stove at home – as long as there is positive pressure, an explosion generally does not occur. In the case of a fire involving highly flammable materials under pressure, it is difficult to extinguish the fire if the fire extinguisher cannot ensure complete isolation from air and sparks. Appropriate pressure reduction must be carried out while isolating the air; it is best to use steam and nitrogen pipelines for purging in order to extinguish the fire, or to smother it with a wet cotton coat. Fire extinguishers are really not effective~~

This post was last edited by LQ198619 on 2017-3-6 at 18:09. It’s a great share, with valuable insights too!

This post was last edited by ming*ang77777 on 2017-3-8 09:35. In the high-benzene hydrogenation unit, after hydrogenation is complete, the mixture goes into a gas-liquid separator; controlling the liquid level in this separator is very important. For various reasons, the quality and quantity of level gauges fail to meet the requirements of the production process, resulting in the liquid level in the gas-liquid separator reaching its maximum, without the central control room being aware of it. Normally, there should be three remote transmitters for the level gauge here, along with one local level gauge, but the actual configuration is insufficient. Furthermore, the viscosity of the material after hydrogenation was quite high, and the ambient temperature was very low, which caused the level gauge to malfunction and prevented timely detection. Finally, the safety valve of the high-pressure separator activated, leading to a leak at the ground flange, which caused a fire and explosion. Caused one person to suffer burns! There is also liquid in the compressor’s intake separator, but it hasn’t reached the outlet – fortunately, that’s a good thing. If the liquid phase of the compressor gets in, the consequences will be disastrous! I hope all my friends will take this as a warning! !