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[vnpetroleum]

Good day everyone,

We are preparing the oil train shutdown on offshore platform to carry out vessel inspection for a lot of vessels such as HP Separator, IP Sep, LP Sep, Electrostatic Heater, HP/LP Flare.... For a vessel, we need positive isolation for man entry. Typically a vessel requires flushing, purging and draining. Using hot seawater to flusing oil/solid => to overflow thru the valve on the top of vessel, then using nitrogen to purge containment gas, check LEL and draining all liquid/solid/residue inside the vessel.

However, there is a option to minimize the shutdown time. Hot seawater will be used to overflow to HP/LP Flare for flushing and "purging". Nitrogen is NOT used to purging. There are some issues to do this option:
1. Structural/ piping support - some piping is designed for gas. Are they rated for seawater? => Engineering Co. confirmed piping support was designed for full water
2. Instrumentation: they are NOT designed for seawater? => No problem in short time
3. Potentially corrosion: trapped water? => They will drain trapped water before start up.
I have never seen purging philosophy like this before. Do you have comment, guidelines, standards relating to this issue? Please share with me.
Thanks - vnpetroelum