Issues with purging for equipment maintenance

I would like to ask the experts: 1. During a major maintenance campaign of petrochemical plants, the pipes need to be emptied of their contents first; does cleaning and purging follow that? If there is a pump in the pipeline, is it necessary to isolate the pump and then flush and purge the pipelines upstream and downstream of the pump separately? In principle, pumps also need to be cleaned; otherwise, if there is material inside the pump, working with fire during maintenance could lead to a fire. Additionally, depending on the maintenance tasks, some equipment and pipelines that do not require cleaning must be isolated using blind flanges, with warning signs placed around them to prevent any use of fire in those areas. Another purpose of using blind flanges for isolation is to prevent flushing water from entering the raw materials or causing pressure issues. 2. Some pipelines need to be treated with steam – do those pipelines have requirements regarding full vacuum conditions, and are there any relevant standards that can be followed? I don’t understand what you mean. Steam cooking should take place at normal or positive pressure; what does \"full vacuum\" mean? 3. If the pipeline at the pump outlet is chosen to be too large, it results in a very low flow rate of the fluid in that pipeline – could this cause any problems? It may cause air to accumulate in the pipeline and lead to significant vibration; normal exhaust during startup is not a major issue.

Rule 1: If the pump also needs to be cleaned, is the cleaning process carried out by circulating the pump? Is it necessary to have the factory perform air blowing after cleaning, and does the pump need to be blown as well during this process? If purging is required, will the pump be damaged as the gas passes through it? Article 2: During the steam cooking process, the pressure is at atmospheric level or slightly positive, but negative pressure is generated in the pipes after the steam condenses. Thank you!