What are the requirements for replacement sampling before opening containers such as the tower bottom?
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There is a distillation tower containing a flammable liquid (with a flash point of around 300°C) and its vapor. If maintenance work on the tower is required, it is necessary first to remove the flammable liquid, then to wash the tower with water, and finally to displace the flammable gases inside the tower with nitrogen. I would like to ask what components need to be analyzed after replacing the combustible gas before the tower can be started up? What are the standards for these components to be considered qualified? Is there any evidence? Are the analysis requirements for opening a tower the same as those for performing hot work on a tower? Please help clarify this! I saw a set of operating procedures stating that nitrogen should be used to displace flammable gases before starting the tower, with the requirement that the explosive concentration be less than 5%. What does this mean? Right?
After removing the oil, we carry out steam cleaning and washing of the tower, then open the manholes for ventilation; there is no need for nitrogen purging. Entry into the tower is permitted only after tests show that levels of combustible gases are zero. Explosivity <5% means that the gas content within is such that the level of explosive gases is <5%.
Is this experience? Is there any evidence?
Portable detectors are used for testing, and one must wear a long-tube respirator or gas mask when entering; no monitoring data is allowed to be taken in, as it is a company policy.
Is it possible to have a combustible gas of 0? Will it take a long time?
Could you provide a contact method? That would make it easier for me to learn from you*
Open the manhole in advance for ventilation; it won’t take long.