Standards for spherical tank replacement
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During annual inspections, spherical tanks need to be soaked in water, and they also require steaming for cleaning and ventilation. What are the respective purposes of tank immersion, tank steaming, and ventilation, and what are the industry standards?
I’ve never been exposed to this process, so I don’t know what the procedures for annual inspection involve. Is it necessary to measure the wall thickness or to inspect the welds? Immersion and steaming in tanks presumably serve to clean the tanks; I’m not sure if it’s necessary for people to go inside to carry out inspections. They still demand to go in and check.
It is necessary to enter the tank, grind the welds, and inspect them.
It depends on the medium stored in the tank; some mediums require boiling, while others do not. However, ventilation is definitely necessary. For annual inspections, personnel need to enter the tank to conduct analyses.
Soaking and steaming the spherical tank is intended to remove the hazardous chemicals inside it; additionally, it serves to prevent self-polymerization and thus facilitate the removal of **reactivity； Ventilation is used to completely displace the hazardous chemicals and nitrogen inside the tank ； The gas concentration inside the tank meets the inspection standards for personnel to carry out grinding work in the tank later. Thank you!
For liquefied gas cylinders, the liquid phase inside the cylinder is generally removed first, and the gas phase is depressurized. Water is then used to fill the cylinder; once the water level approaches the top of the cylinder, nitrogen is introduced repeatedly along with pressure release to discharge any remaining liquefied gas. After that, the water is drained, the manhole is opened for ventilation, and the concentration of combustible gases is checked.
For the acrylic storage tank here, the process involves first pouring the material in liquid form, followed by gas-phase recovery; a blind flange is installed, water is introduced, and after 24 hours of soaking, the water is drained. The manhole is removed, scaffolding is set up both inside and outside the tank, the welds are polished, and once magnetic particle testing shows no defects, the tank can be put into normal use. Water is introduced to reduce the time required for displacement as well as the amount of nitrogen used, and it also helps to check for any settlement of the tank. Steaming should allow for a more thorough removal of toxic and harmful gases
I have a question: could iron powder generated from grinding welds internally create an explosive environment? Aluminum powder can do that, so could iron powder as well?
Usually, the welded joints that need to be polished are iron containers, and ventilation systems must remain in operation throughout the polishing process； As long as the flammable and explosive materials inside the tank are completely removed ； Rust is not harmful ； Such as internal grinding in shipyards, etc